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HER2)-low expression is a predictive biomarker for novel anti-HER2 antibody-drug conjugates. However, little is known about its clinical significance in inflammatory breast cancer (IBC).Patients diagnosed with HER2-negative IBC between December 1999 and December 2020 were identified from the Dana-Farber Cancer Institute IBC registry. Patients were divided into HER2-low (IHC 1+ or 2+/ISH-) and HER2-zero (IHC 0), comparing clinicopathologic features and disease outcomes between the two subgroups.The study included 276 patients. Among patients with stage III (n = 209) and stage IV (n = 67) IBC, 54% and 39% had HER2-low tumours, respectively. Oestrogen receptor (ER)-expressing tumours were more common in patients with HER2-low versus HER2-zero stage III IBC (65% versus 38%, p lt; 0.01). Among stage III patients undergoing surgery (n = 182), pathologic complete response (pCR) rates were higher for HER2-zero versus HER2-low IBC (11% versus 6%, OR: 1.8, 95%CI:0.6-5.3), but minimal differences persisted when separately analysing pCR by ER status. Similar invasive disease-free survival (iDFS) outcomes were observed among ER-positive HER2-zero versus HER2-low IBC (48-month iDFS: 63% versus 63%, HR: 1.10, 95%CI:0.57-2.13) and ER-negative HER2-zero versus HER2-low IBC (48-month iDFS: 28% versus 25%, HR: 1.19, 95%CI:0.69-2.04). Differences in overall survival (OS) were small, both among ER-positive HER2-zero versus HER2-low IBC (48-month OS: 80% versus 81%, HR: 0.82, 95%CI:0.39-1.73) and ER-negative HER2-zero versus HER2-low IBC (48-month OS: 34% versus 47%, HR: 1.34, 95%CI: 0.74-2.41).Marginal differences in clinicopathologic features and outcomes were observed in HER2-low versus HER2-zero IBC when controlling for ER status, not supporting the definition of HER2-low as a distinct subtype of IBC.

Background: Inflammatory breast cancer (IBC) is unresectable at presentation, thus neoadjuvant systemic therapy (NAS) is the primary treatment for this aggressive disease. Eribulin (E) (Eisai Co., Ltd) is a synthetic analog of Halichondroin B that suppresses microtubule growth. Its properties of inducing a mesenchymal-to-epithelial transition and normalizing the vasculature of mammary tumors are particularly relevant to IBC. Pre-clinical data revealed changes in dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI) parameters after exposure to E, thought to reflect tumor vasculature remodeling. We sought to examine the efficacy of E-containing NAS specifically for patients (pts) with HER2- IBC. We also characterized changes in breast DCE-MRI and diffusion weighted MRI (DWI) between baseline and 1 week (wk) after NAS. Methods: Pts with newly diagnosed HER2- IBC received 4 cycles of E 1.4 mg/m2 day (D)1, D8 every 21 D followed by 4 cycles of dose-dense (dd) doxorubicin (A) 60 mg/m2 + cyclophosphamide (C) 600mg/m2 every 2 wk followed by modified radical mastectomy (MRM) + postmastectomy radiation (PMRT) on a phase II prospective study (Cohort A). Primary endpoint was pathologic complete response (pCR) defined as no invasive disease in breast + axillary lymph nodes. Based on a Simon 2-stage design, if ≥ 2 of 16 pts had pCR then enrollment would continue to 25, with the regimen worthy of study if pCR ≥ 0.30 and not if pCR ≤ 0.10 (α=0.10, β=0.10). A second cohort was opened, changing the NAS sequence to ddAC followed by E (Cohort B). All pts had 2 research breast biopsies (rbx) for genomic analysis at baseline and 1 wk after first dose of NAS. An imaging study evaluated breast DCE-MRI and DWI at baseline and 1 wk after first dose of NAS. Tofts 2-compartment pharmacokinetic (PK) model calculated Ktrans, Ve, Kep, and iAUC from DCE. ADC was calculated from DWI. The change in Ktrans, Ve, Kep, iAUC, and ADC between baseline and wk 1 was evaluated using a signed-rank test. The magnitude of these changes was compared between Cohort A and Cohort B using a Wilcoxon rank-sum test. All testing was two-tailed and exact p-values were used; p-value < 0.05 were considered statistically significant. Results: 22 pts were enrolled, 16 pts in Cohort A and 6 pts in Cohort B before the study was closed due to slow accrual. Median age was 58 years, 3 pts (13.6%) had triple negative disease. 13 pts (59%) were postmenopausal. All but 1 had stage III disease. All 22 pts completed NAS followed by MRM + PMRT. 19 pts completed full course of NAS, 1 pt received E followed by 3 cycles of AC and 2 pts received 3 cycles of E in addition to 4 cycles of AC. In Cohort A, 1/16 pts had pCR (6.3%; 80% CI 0,22.2%). At a median follow up of 51 months, 3 pts had distant disease recurrence with 1 death; no local-regional recurrence. 7 pts experienced grade (gd) 3 or 4 adverse event (AE); most common were neutropenia and aminotransferase increase. 10 pts participated in the DCE-MRI and DWI substudy: 5 from Cohort A, 5 from Cohort B. Decrease in value from baseline to wk 1 was detected in Ktrans (median -49), Ve (-128), and iAUC (-57). The magnitude of changes was not different when comparing Cohort A to Cohort B. There was no significant change in Kep or ADC. Given the small size of each group, a lack of statistical significance should not be interpreted as suggestive of no effect. Evaluation of changes in angiogenesis- and EMT-related gene expression in rbx + residual disease is ongoing.Conclusion: A regimen of E + ddAC is tolerable NAS for HER2- IBC. All pts underwent curative surgery despite low pCR rate, commonly observed in ER+ IBC. There were changes in some DCE-MRI parameters after exposure to chemotherapy but may not be specific to E. Studies specifically designed for IBC are needed to enhance the understanding of this disease. Clinical trial: NCT02623972 Citation Format: Filipa Lynce, Eren D. Yeh, Meredith M. Regan, Lei Qin, Camden P. Bay, Ian Krop, Beth T Harrison, Faina Nakhlis, Jennifer Bellon, Beth Overmoyer. A phase 2 study of neoadjuvant systemic therapy with eribulin followed by doxorubicin and cyclophosphamide for HER2-negative inflammatory breast cancer [abstract]. In: Proceedings of the 2021 San Antonio Breast Cancer Symposium; 2021 Dec 7-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2022;82(4 Suppl):Abstract nr P2-12-18.

Objective To review MRI findings of pure lobular neoplasia (LN) on MRI guided biopsy, evaluate surgical and clinical outcomes, and assess imaging findings predictive of upgrade to malignancy. Methods HIPAA compliant, IRB-approved retrospective review of our MRI-guided breast biopsy database from October 2008–January 2015. Biopsies yielding atypical lobular hyperplasia or lobular carcinoma in situ were included in the analysis; all biopsy slides were reviewed by a dedicated breast pathologist. Imaging indications, MRI findings, and histopathology were reviewed. Statistical analysis was performed using the two-tailed Fisher exact-test and the t-test, and 95% CIs were determined. A p Results Database search yielded 943 biopsies in 785 patients of which 65/943 (6.9%) reported LN as the highest risk pathologic lesion. Of 65 cases, 32 were found to have LN as the dominant finding on pathology and constituted the study population. All 32 findings were mammographically and sonographically occult. Three of 32 (9.3%) cases of lobular neoplasia were upgraded to malignancy, all LCIS (one pleomorphic and two classical). The most common MRI finding was focal, heterogenous non-mass enhancement with low T2 signal. No clinical features or imaging findings were predictive of upgrade to malignancy. Conclusion Incidence of pure lobular neoplasia on MRI guided biopsy is low, with comparatively low incidence of upgrade to malignancy. No imaging or clinical features are predictive of upgrade on surgical excision, therefore, prudent radiologic-pathologic correlation is necessary.

Background: Advances in HER2-directed therapy have significantly improved survival in HER2+ metastatic breast cancer. Approximately 30% of de novo metastatic inflammatory breast cancer (mIBC) is HER2+, though there has been limited IBC representation in clinical trials evaluating the role of HER2-directed agents as first-line metastatic therapy. Elevated rates of locoregional progression or recurrence (LRPR) with systemic therapy alone also raise the question of whether trimodality therapy (TMT) may improve outcomes in IBC patients (pts) with limited metastatic disease, particularly in the setting of increasingly effective anti-HER2 therapy. Methods: Pts diagnosed with de novo HER2+ mIBC were identified from an IRB-approved IBC registry at Dana-Farber Cancer Institute. Clinical, pathology and treatment data were manually abstracted by chart review. Progression-free survival (PFS) was defined as time from IBC diagnosis to LRPR, distant progression/relapse or death (in the absence of event, censored at date of last follow-up). Overall survival (OS) was defined as time from IBC diagnosis to death from any cause or censored at date last known alive. For pts who underwent surgery of the primary tumor, pathologic complete response (pCR) was defined as no residual invasive carcinoma in the breast and axilla and survival was estimated from date of surgery. Median PFS and OS were estimated by Kaplan-Meier method; cumulative incidence of CNS metastasis and LRPR were estimated with death as competing risk. Results: 78 pts diagnosed between 1998-2019 with de novo HER2+ mIBC (41 hormone receptor (HR)-positive; 37 HR-negative) were identified. Median age at diagnosis was 53 years (yr; range: 24-91). Sites of metastatic disease at presentation included bone only (n=12), lymph node/contralateral chest wall only (n=17), bone and lymph node (n=5), visceral (n=40) and CNS with extracranial disease (n=4). As initial HER2-directed therapy, 37 pts received trastuzumab (H), 40 H plus pertuzumab and 1 T-DM1. At a median follow-up of 2.7 yr in the overall cohort, median PFS was 1.0 yr (IQR: 0.5-2.8 yr; 60 events) and median OS was 4.6 yr (IQR: 2.9-8.7 yr; 39 deaths). 34 pts had CNS metastasis with a cumulative incidence of 20% and 28% at 1 and 2 yr, respectively. LRPR developed in 26 pts, of which 16 occurred within 12 months (mo) of diagnosis. Cumulative incidence of LRPR at 1 and 2 yr was 21% and 29%, respectively. In 41 pts (53%), mastectomy was performed after receipt of systemic therapy. Median time from IBC diagnosis to surgery was 7.5 mo (IQR: 6.0-9.9 mo). Radiation was administered in 33 pts, 3 pre- and 30 post-mastectomy. Median OS from surgery was 5.2 yr (IQR: 3.1-8.4 yr). 9/41 pts (22%) achieved pCR; all pCR pts were alive at 1.3-8.9 yr since surgery. To investigate the value of therapy for locoregional control, a landmark analysis was performed in the subset of pts alive and LRPR free at 12 mo from diagnosis (n=56). 27 had surgery within 12 mo from diagnosis and 29 did not. LRPR occurred in 10/56; 9 were among pts who did not undergo surgery. Cumulative LRPR incidence at 1 and 2 yr since the 12 mo landmark was 21% and 29%, respectively, in pts who did not undergo surgery, and 0% at both time points in pts who had surgery (1 LRPR at 8 yr). Conclusion: Long-term outcomes in de novo HER2+ mIBC are overall similar to those reported in metastatic HER2+ non-IBC. More than half of pts underwent systemic and local therapy with good locoregional control and prolonged survival, suggesting a potential role for aggressive local therapy in this mIBC subset with favorable prognosis and effective systemic therapy. The high incidence of early CNS involvement in de novo HER2+ mIBC prompted us to explore this group in detail (Warren SABCS 2020 abstract). Larger studies are needed to better understand the effectiveness of TMT in HER2+ mIBC, highlighting the importance of collaborative research efforts in this rare subset. Citation Format: Ana C. Garrido-Castro, Samuel M. Niman, Marie Claire Remolano, Jennifer M. Rosenbluth, Caroline Block, Laura E. Warren, Jennifer Bellon, Beth T. Harrison, Faina Nakhlis, Meredith Regan, Beth Overmoyer. Clinical outcomes in de novo metastatic HER2-positive inflammatory breast cancer [abstract]. In: Proceedings of the 2020 San Antonio Breast Cancer Virtual Symposium; 2020 Dec 8-11; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2021;81(4 Suppl):Abstract nr PS10-34.

Background: Inflammatory breast cancer (IBC) is the most aggressive locally advanced breast cancer subtype. It is associated with loco-regional recurrence rates of 12-25%, and neoadjuvant chemotherapy (NAC) followed by modified radical mastectomy and comprehensive chest wall and regional nodal radiotherapy remain the standard of care. As has been demonstrated in non-IBC, achievement of pathologic complete response (pCR) has been shown to be associated with improved loco-regional control, recurrence-free and overall survival. Advances in NAC for IBC have resulted in improved pCR rates in both the breast and the axilla, with overall axillary pCR rates of approximately 30%, reaching as high as 67% in patients with HER2-positive disease receiving HER2-directed therapy. Hypothesis: Sentinel lymph node biopsy (SLNB) may be feasible in IBC patients who experience a good clinical and pathologic response in the axilla to NAC. Primary Objective: To evaluate the sentinel lymph node (SLN) identification rate in stage III IBC patients who experience cN0 status at completion of NAC. Secondary Objective: To assess the incidence of lymphedema following standard local-regional therapy for IBC. Methods and Study procedures: In this feasibility study, 50 patients with cT4dN0-2M0 IBC will be enrolled in order to evaluate 40 patients whose axillary nodal status becomes cN0 upon completion of NAC. All patients will undergo a research breast biopsy and lymphoscintigram pre and post NAC to evaluate lymphatic drainage patterns and patency of breast and axillary lymphatics. Post NAC lymphoscintigraphy will be appropriately timed for pre-operative SLN mapping and all patients will undergo SLNB using dual tracers (Tc99 Sulfur colloid and blue dye) with immediate axillary lymph node dissection (ALND), at the time of mastectomy. The patient-reported Lymphedema Symptom Intensity and Distress Survey (LSIDS-A) will be collected at 6 timepoints. Patients will be followed for 2 years post-surgery for oncologic outcomes. Correlatives: We plan to evaluate genetic and phenotypic heterogeneity in IBC and to assess markers of angiogenesis and lymph-angiogenesis associated with IBC, as well as to explore immunologic aspects of the tumor microenvironment and their association with pCR. Statistics: The identification rate will be calculated as number of patients in whom SLNs were successfully identified over the number of patients with cN0 disease after NAC in whom SLN mapping was attempted. Using a Simon two-stage design (α=.10, β=.10), a SLN identification rate of ≥90% would result in considering this procedure feasible whereas an identification rate of ≤75% (null hypothesis) would lead to the conclusion that it is not feasible. In the first stage, if greater than 18 of 25 patients have SLNs identified, then a total of 40 patients will be enrolled. If fewer than 33 of 40 patients have SLN identified, then the null hypothesis is rejected. Citation Format: Faina Nakhlis, Meredith Regan, Heather Jacene, Beth Harrison, Jennifer Bellon, Jean Landry, Eren Yeh, Elizabeth Mittendorf, Beth Overmoyer, Tari King. Refining loco-regional therapy for inflammatory breast cancer protocol in progress [abstract]. In: Proceedings of the 2020 San Antonio Breast Cancer Virtual Symposium; 2020 Dec 8-11; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2021;81(4 Suppl):Abstract nr PS14-21.

Non-classic lobular carcinoma in situ (NC-LCIS) represents a spectrum of lesions, histologically distinct from classic LCIS (C-LCIS) and ductal carcinoma in situ (DCIS). Several studies have reported on the safety of breast conservation (BCS) in patients with DCIS or invasive breast cancer and concomitant C-LCIS, yet there are no data addressing this question for patients with concomitant NC-LCIS. We evaluated local recurrence (LR) after BCS in patients with DCIS or invasive cancer and concomitant NC-LCIS.We searched institutional databases using natural language processing to identify patients with DCIS or invasive breast cancer and concomitant NC-LCIS treated with BCS between 2000 and 2015. Charts were reviewed to collect demographics, disease and treatment details, and recurrence events. All results represent descriptive analyses.We identified 71 patients with DCIS (n = 13) or invasive cancer (n = 58) and concomitant NC-LCIS treated with BCS. Median patient age was 59 years (33-77 years), and median invasive tumor size was 1.2 cm (0.1-6.9 cm); 62% of DCIS and 79% of invasive cancer patients had hormone receptor (HR)-positive disease. Among DCIS patients, seven (54%) received radiation and none hormonal therapy. Among those with invasive cancer, 52 (90%) received radiation, 17 (29%) received chemotherapy and 44 of 55 with HR-positive disease (78%) received hormonal therapy. At median follow-up of 79 months (1-265 months), the LR rate was 8% and 2% among patients with DCIS and invasive cancer, respectively.NC-LCIS is rarely present in association with DCIS or invasive cancer, and it does not appear to impact LR outcomes following BCS.

Pleomorphic LCIS (P-LCIS) and florid LCIS (F-LCIS) are morphologic variants distinguished from classic LCIS by marked nuclear pleomorphism and/or an expansile growth pattern with or without necrosis. Given the rarity of these LCIS variants, little data exist regarding their molecular pathogenesis, natural history, and optimal management. The purpose of this study was to genomically profile LCIS variants to gain further insight into their biology. Nineteen cases of pure LCIS variants (17 P-LCIS, 2 F-LCIS) diagnosed on core needle biopsy at our institution from 2006 to 2017 were included, five of which were upgraded to invasive cancer at excision. Macrodissected lesions were analyzed by a hybrid-capture next generation sequencing assay that surveyed exonic sequences of 447 genes for mutations and copy number variations (CNVs) and 191 regions across 60 genes for structural rearrangements. LCIS variants were all confirmed as E-cadherin negative by immunohistochemistry. Receptor profiles among the 17 P-LCIS cases included HR+/HER2- (nine cases), HR+/HER2+ (three cases), HR-/HER2+ (two cases), and HR-/HER2- (three cases). The two F-LCIS cases were HR+/HER2- and HR+/HER2+. All LCIS variants had genetic alterations consistent with a lobular phenotype including 1q gain (16 cases), 16q loss (18 cases), and CDH1 mutations (18 cases). Highly recurrent ERBB2 alterations were noted including mutations (13 cases) and amplifications (six cases). Other significant alterations included mutations in PIK3CA (six cases), RUNX1 (four cases), ERBB3 (four cases), and CBFB (three cases), as well as amplification of CCND1 (five cases). A TP53 mutation was identified in one case of HR-/HER2+ P-LCIS with signet ring cell features that lacked 1q gain and 16q loss. P-LCIS and F-LCIS contain genetic alterations characteristic of lobular neoplasia; however, these LCIS variants are distinguished from classical LCIS reported in the literature by their highly recurrent ERBB2 alterations.

Introduction: Inflammatory breast cancer (IBC) is a clinical diagnosis that spans all breast cancer subtypes. The clinical course of IBC is associated with poorer outcomes than molecular subtype-matched non-IBC and represents an unmet need in breast cancer therapy. IBC is characterized by invasive dermal lymphatic tumor emboli (DLTE) resulting in erythema and edema of the breast. This suggests a common molecular theme, which if identified and targeted, could reduce mortality. Although several genomic and transcriptomic studies of IBC have been performed, no definitive genomic drivers have been identified. We hypothesized that the genomic features of IBC remain undiscovered because only the primary tumor has been analyzed, rather than the population of tumor cells responsible for the phenotype (i.e. DLTE). However, analysis of DLTE is challenging due to lack of effective technologies to purify these cells from the more abundant stroma. Methods: We utilized the Millisect automated dissection (AD) technology, which can selectively recover tissue from targeted areas as small as 200µ2 on standard FFPE sections, on matched skin with DLTE and primary tumor slides from 7 post-treatment IBC mastectomy specimens. We performed RNA sequencing (RNAseq) on AD-enriched primary tumor and DLTE, on full sections from the same samples (including stroma and tumor) and on tissue remaining post-AD (containing residual stroma after tumor cell extraction). Results: RNAseq analysis in AD-enriched primary tumor and DLTEs identified unique transcriptional patterns upregulated in DLTE indicative of lymphatic trafficking (e.g. CCL21), immunosuppression (e.g. S100A9/calprotectin), and myofibroblastomic differentiation (e.g. CD34, desmin, alpha-smooth muscle actin). Gene set enrichment corroborated these inferences, demonstrating DLTE enrichment of gene sets involved in chemokine/trafficking, tumor stemness, and smooth muscle contraction/migration. These gene sets were not apparent in samples extracted from the full sections. Conclusions: Automated dissection technology enables specific investigation on the limited epithelial material that comprises inflammatory breast cancer involving dermal lymphatics. Further investigation, with cohort expansion to increase sample size and statistical power, will focus on pre-treatment skin biopsies with DTLE and matched breast tumor tissue. We expect this will yield novel insights into the biology and treatment of this unique phenotype. Citation Format: Jennifer M Giltnane, Justin M Balko, Nickles Dorothee, Sarajane Nghiem, Anneleen Daemen, Emmanuel Naouri, Amy A Lo, Beth T Harrison, Emily J Schlosnagle, Charles Havnar, Carmina Espiritu, Daniel G Stover, Beth A Overmoyer. Automated tissue dissection of dermal lymphatic emboli in inflammatory breast cancer enhances accuracy of transcriptional analysis [abstract]. In: Proceedings of the 2019 San Antonio Breast Cancer Symposium; 2019 Dec 10-14; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2020;80(4 Suppl):Abstract nr P6-15-02.

Invasive lobular carcinoma with extracellular mucin (ILCEM) is a rare histologic subtype of breast cancer. Little is known about the pathologic or genomic signatures that distinguish ILCEM from classic invasive lobular carcinoma (ILC) or mucinous carcinoma. We studied 17 breast cancers with lobular morphology and extracellular mucin. Thirteen tumors with sufficient tissue for DNA extraction were analyzed by a next generation sequencing (NGS) assay that interrogates 447 genes for mutations and copy number variations (CNVs). Median patient age was 66 yrs (range: 31-77 yrs). Sixteen patients presented with masses, 7 of which were2 cm. Seven patients had lymph node metastases. The cases of ILCEM were moderately (n = 13) or poorly differentiated (n = 4), frequently exhibiting variant morphology that has not been previously described or emphasized, including grade 3 nuclei (n = 11), diffuse signet ring cells (n = 10), solid growth (n = 4), tumor necrosis (n = 3) or apocrine features (n = 2). All tumors showed absent or reduced membranous E-cadherin expression. Concurrent lobular carcinoma in situ (LCIS) was seen in 11/17 cases, 1 of which was a striking example of signet ring cell LCIS with extracellular mucin. Receptor profiles were ER+/HER2- (n = 15) and ER+/HER2+ (n = 2). With a median follow-up of 83.5 months (range: 3-171 months) in 12 patients with available information, 8 patients had recurrences resulting in 4 cancer-related deaths. The most common CNVs were 16q loss (n = 11) and 1q gain (n = 9). CDH1 gene-level alterations were detected in all but one case, including frameshift (n = 7), nonsense (n = 2), and donor splice site (n = 1) mutations and indels (n = 2). Recurrent mutations were also seen in PIK3CA (n = 3), POLQ (n = 3), TP53 (n = 3), ERBB3 (n = 3), ERBB2 (n = 2), and RUNX1 (n = 2). Genes with recurrent amplifications included GATA3 (n = 4), FOXA1 (n = 3), CCND1 (n = 2). Our data highlights ILCEM as a distinct variant of ILC that often presents with higher-grade and variant morphologic features and is associated with an aggressive clinical course. NGS data support an overall lobular-type molecular profile and reveal potentially targetable alterations in a subset of cases with recurrence.

Secretory carcinoma is a special-type breast carcinoma underpinned by a recurrent t(12;15)(p13;q25) translocation resulting in ETV6-NTRK3 gene fusion. Immunohistochemistry (IHC) using a pan-TRK antibody has been recently shown to help identify NTRK rearrangements in other tumor types. The purpose of this study was to assess the diagnostic utility of pan-TRK IHC in secretory carcinoma of the breast. Pan-TRK IHC was performed using a rabbit monoclonal antibody on whole sections of 24 breast secretory carcinomas and tissue microarray sections of other breast carcinoma types (n=203) and histologic mimics (n=15). Cases were assessed for staining intensity and localization. The 24 patients with secretory carcinoma had a median age of 44 years and a median tumor size of 1.0 cm. ETV6 fluorescence in situ hybridization was positive in all cases tested (n=20). Twenty-three cases (95.8%) showed staining with pan-TRK, which was exclusively nuclear in 19, primarily nuclear with weak cytoplasmic staining in 3, and primarily cytoplasmic with focal nuclear staining in 1. The nuclear staining was diffuse in 17 and at least focally strong in 17. The only pan-TRK negative case was a core biopsy with limited tumor. Among the 203 nonsecretory carcinomas, 21 (10.3%) showed focal, weak nuclear staining in

Active surveillance trials for low-risk ductal carcinoma in situ (DCIS) are in progress in the United States and Europe. In some of these trials, the presence of comedo necrosis in the DCIS has been an exclusion criterion for trial entry. However, the minimum amount of necrosis required by pathologists for a diagnosis of comedo necrosis is not well-defined. We surveyed 35 experienced breast pathologists to assess their diagnostic threshold for comedo necrosis. Pink circles representing necrosis ranging in extent from 10 to 80% of the duct diameter were superimposed on eight replicate histologic images of a single duct involved by low nuclear grade, solid pattern DCIS. These images were circulated by e-mail to the participating pathologists who were asked to select the image that represents the minimum amount of necrosis that they require for a diagnosis of comedo necrosis. Among the 35 participants, the minimum extent of the duct diameter required for a diagnosis of comedo necrosis was 10% for 4 pathologists, 20% for 5, 30% for 11, 40% for 7, 50% for 6, 60% for 1 and 70% for 1. There was no single threshold about which more than one-third of the pathologists agreed met the minimal criteria for comedo necrosis. We conclude that even among experienced breast pathologists, the threshold for comedo necrosis is highly variable. Our findings highlight the need for a standardized definition of comedo necrosis as a trial criterion, and more generally where it may be used as a marker of increased risk of recurrence for therapeutic decision making.

Background: Inflammatory breast cancer (IBC) is an aggressive form of breast cancer that remains relatively understudied. We examined the efficacy of neoadjuvant dual-HER2 blockade (trastuzumab (H) and pertuzumab (P)) combined with paclitaxel (T) in HER2+ IBC, including a planned analysis to elucidate associations between the tumor immune microenvironment profile and response to therapy. Methods: An IRB-approved, single-arm phase II trial for patients (pts) with newly diagnosed HER2+ IBC was conducted. Pts had a pre-treatment biopsy of the affected breast (D1) followed by a loading dose of HP. A second biopsy was performed 1 week (wk) later (D8), when T (80mg/m2/wk x 16 wks) was added to HP. Responding pts underwent modified radical mastectomy (MRM) where residual disease was collected. The primary objective was to determine the rate of pathologic complete response (pCR) defined as ypT0/isN0. Residual Cancer Burden (RCB) was also determined. Tumor specimens from D1, D8 and MRM were assessed for disease cellularity and scored for percentage of tumor infiltrating lymphocytes (TILs): low=0-10%, intermediate=11-59%, high>60%. RNA-sequencing was performed on tumor tissue from D1 and D8 to explore the impact of short-term HP treatment on the tumor transcriptomic profile and to identify potential predictors of pCR. Results: 23 pts with HER2+ IBC were enrolled between 8/2013-6/2017. Mean age was 48 years (range 32-74); 11 pts (48%) had estrogen and progesterone receptor (ER/PR) negative disease. Matched tumor biopsies (D1, D8) were obtained in all 23 pts; 21 underwent MRM; 1 was lost to follow-up and 1 had disease progression. In the intent to treat analysis, 10/23 (43%) pts achieved a pCR and 7 (30%) had RCB-1. Ten of the 22 evaluable pts achieved a pCR (45.5%). TILs were evaluable in 20/23 (87%) matched tumor biopsies (D1, D8). Among the D1 biopsy specimens: 19 (95%) had low levels, 2 (10%) had intermediate levels, and none had high levels. When D1 TIL levels were compared with D8 levels, 3(15%) had an increase in TILs, 16(80%) had no change in TIL levels, and 1(5%) had a decrease in the level of TILs. Both samples with intermediate levels and 2 of 3 samples with high levels of TILs on D1 and D8 were seen in ER/PR negative disease. An evaluation of biopsy specimens associated with subsequent pCR using GO enrichment analysis from the RNA-Seq data showed significant upregulation of several immune-process related gene expression signatures both at D1 and D8 (e.g. antigen processing and presentation, TCR signaling, NK cell cytotoxicity, p-value: 2.99E-48 to 1.39E-16) when compared with those associated with residual disease at the time of MRM. Across the entire cohort, D8 biopsies showed evidence of upregulated anti-tumor immunity compared to D1 biopsies (p-value: 9.57E-06 to 0.012). Notably, this change from D1 to D8 was largely restricted to tumors that achieved a pCR. Conclusion: THP for 16 weeks was a highly effective treatment for HER2+ IBC. Immune activation as determined by gene expression signatures predicted pCR, and moreover upregulation of anti-tumor immunity after 1 wk of HP might further predict a complete pathologic response to therapy. ClinicalTrials.gov identifier: NCT01796197 Citation Format: Pernas S, Goel S, Harrison BT, Hu J, Johnson N, Regan M, Chichester LA, Nakhlis F, Schlosnagle EJ, Winship G, Guerriero JL, Parsons H, Mittendorf EA, Overmoyer B. Assessment of the tumor immune environment in inflammatory breast cancer treated with neoadjuvant dual-HER2 blockade [abstract]. In: Proceedings of the 2018 San Antonio Breast Cancer Symposium; 2018 Dec 4-8; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2019;79(4 Suppl):Abstract nr PD3-08.

Purpose: The pathologic hallmark of inflammatory breast cancer (IBC) is the presence of tumor emboli within the papillary and reticular dermis of the skin, termed dermal lymphatic invasion (DLI). DLI can be confirmed with a skin-punch biopsy in approximately 75% of cases, but its presence is not required for the diagnosis of IBC because of variability of tumor emboli in affected areas. The impact of confirming DLI by skin biopsy on the clinical outcome of IBC is unknown. We hypothesize that the ability to confirm DLI by biopsy is associated with a higher tumor emboli load and consequently a poorer disease prognosis. Therefore, we examined whether documented DLI was associated with poorer overall survival (OS) in IBC. Methods: Clinical characteristics were evaluated among 286 women presenting with IBC between 1999 and 2016 and enrolled in the IRB-approved IBC registry at Dana-Farber Cancer Institute. Kaplan-Meier curves were used to estimate overall survival and the log-rank test to examine survival differences based upon the presence of DLI. Multivariable Cox proportional hazards models were used to estimate hazard ratios (HR) and 95% confidence intervals for associations of DLI and risk of death among women with IBC. Results: A total of 102 deaths occurred in our study population over a median follow-up of 2.5 years (yr) (range 10 days to 16 yr). Compared to IBC without DLI, IBC with confirmed DLI was more likely to be associated with the presence of lymphovascular invasion in breast biopsies (73.1% vs. 37.7%; p-value Conclusions: Our findings suggest that IBC presenting with documented DLI on skin biopsy may vary with regard to clinical characteristics at diagnosis, including lymphovascular invasion within the breast, edema of the skin of the breast, and the presence of de novo metastases. These clinical distinctions suggest potential differences in biology of IBC according to the presence or absence of DLI, and the extent of tumor emboli. However, in this study, DLI was not found to be an independent prognostic factor in IBC with respect to OS. Due to the variability in the clinical features of IBC at presentation and inherent complexities in selecting skin biopsy sites, studies to investigate the accuracy of determining DLI based on punch biopsy are necessary to more comprehensively assess the impact of DLI on clinical outcomes in IBC. Citation Format: Hirko KA, Schlossman J, Harrison BT, Yeh ED, Jacene HA, Nakhlis F, Schlosnagle E, Overmoyer BA. Association of dermal lymphatic involvement and survival in inflammatory breast cancer [abstract]. In: Proceedings of the 2018 San Antonio Breast Cancer Symposium; 2018 Dec 4-8; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2019;79(4 Suppl):Abstract nr P6-09-10.

OBJECTIVES Dermal lymphatic invasion (DLI) with tumor emboli is a common pathologic characteristic of inflammatory breast cancer (IBC), although its presence is not required for diagnosis. We examined whether documented DLI on skin biopsy was associated with survival and time to recurrence or progression in IBC. MATERIALS AND METHODS A total of 340 women enrolled in the IBC Registry at Dana-Farber Cancer Institute between 1997 and 2019 were included in this study. Kaplan-Meier curves and multivariable Cox proportional hazards models were used to estimate hazard ratios and 95% confidence intervals for associations of DLI and overall survival, time to locoregional recurrence/progression, and distant metastasis by stage at presentation. RESULTS DLI was detected in 215 (63.2%) of IBC cases overall. At disease presentation, IBC with DLI had a higher prevalence of de novo metastases (37.7% vs. 26.4%), breast skin ulceration (6.1% vs. 2.4%), and lymphovascular invasion within the breast parenchyma (52.9% vs. 25.5%) and a lower prevalence of palpable breast mass (48.2% vs. 70.6%) than IBC without DLI. Over a median follow-up of 2.0 years, 147 deaths occurred. DLI was not associated with survival or recurrence in multivariable models (all P ≥0.10). For example, among women with stage III disease, hazard ratios (95% confidence intervals) for DLI presence was 1.29 (0.77-2.15) for overall survival, 1.29 (0.56-3.00) for locoregional recurrence, and 1.71 (0.97-3.02) for distant metastasis. CONCLUSION Although the extent of tumor emboli in dermal lymphatics may be associated with biological features of IBC, DLI was not an independent prognostic marker of clinical outcomes in this study.

The US Food and Drug Administration (FDA) approved the PD-L1 immunohistochemical assay, SP142, as a companion test to determine eligibility for atezolizumab therapy in patients with advanced triple negative breast cancer (TNBC) but data in lung cancer studies suggest the assay suffers from poor reproducibility. We sought to evaluate reproducibility and concordance in PD-L1 scoring across multiple pathologists. Full TNBC sections were stained with SP142 and SP263 assays and interpreted for percentage (%) immune cell (IC) staining by 19 pathologists from 14 academic institutions. Proportion of PD-L1 positive cases (defined as ≥1% IC) was determined for each assay as well as concordance across observers. We utilized a new method we call Observers Needed to Evaluate Subjective Tests (ONEST) to determine the minimum number of evaluators needed to estimate concordance between large numbers of readers, as occurs in the real-world setting. PD-L1 was interpreted as positive with the SP142 assay in an average 58% of cases compared with 78% with SP263 (p

Uterine serous carcinoma is an aggressive subtype of endometrial cancer that accounts for fewer than 10% of endometrial carcinomas but is responsible for about half of deaths. A subset of cases has HER2 overexpression secondary to ERBB2 gene amplification, and these patients may benefit from anti-HER2 therapies, such as trastuzumab. HER2 protein overexpression is currently assessed by immunohistochemistry (IHC) and ERBB2 gene amplification by fluorescence in situ hybridization (FISH). Targeted next-generation sequencing (NGS) is increasingly used to routinely identify predictive and prognostic molecular abnormalities in endometrial carcinoma. To investigate the ability of a targeted NGS panel to detect ERBB2 amplification, we identified cases of uterine serous carcinoma (n = 93) and compared HER2 expression by IHC and copy number assessed by FISH with copy number status assessed by NGS. ERBB2 copy number status using a combination of IHC and FISH was interpreted using the 2018 ASCO/CAP guidelines for breast carcinoma. ERBB2 amplification by NGS was determined by the relative number of reads mapping to ERBB2 in tumor DNA compared to control nonneoplastic DNA. Cases with copy number ≥6 were considered amplified and copy number

A diagnosis of non-classic lobular carcinoma in situ (NC-LCIS) encompasses a variety of lesions with poorly characterized natural history. We evaluated upgrade rates and factors associated with upgrade to malignancy following a core biopsy diagnosis of NC-LCIS, and its natural history. Upon Institutional Review Board approval, pathology databases were searched for NC-LCIS core biopsy diagnoses (carcinoma in situ [CIS], CIS with ductal and lobular features [CIS/DLF], pleomorphic LCIS [P-LCIS], variant LCIS [V-LCIS], LCIS with necrosis). Cases with available core and excision pathology were included, while cases with concurrent ipsilateral invasive carcinoma (IC), ductal carcinoma in situ (DCIS), and/or atypical ductal hyperplasia were excluded. Overall, 121 NC-LCIS cases were identified from 1998 to 2017. We excluded 46 cases with concurrent cancer; 75 patients with 76 NC-LCIS core biopsy diagnoses followed by excision formed our study cohort. Median age was 56 years (range 41–83), and all imaging findings were classified as Breast Imaging Reporting and Data System 4; calcifications were the most common biopsy indication (80%). Excision yielded malignancy in 27 (36%) patients (IC 17, 63%; DCIS alone 10, 37%). We were unable to identify radiologic or pathologic features predictive of upgrade. Of 49 pure NC-LCIS cases, 15 (31%) had mastectomy, 9 (18%) had excision and radiation, and 25 (51%) had excision alone. At a median follow-up of 58 months (range 1–224), 1/25 (4%) patients with excision alone developed ipsilateral DCIS 14 months later. In this series of NC-LCIS, 36% of cases were upgraded, supporting routine excision. We were unable to identify predictors of upgrade. Among 25 patients with pure NC-LCIS, only one patient developed a future ipsilateral cancer. Further study of the natural history of NC-LCIS is warranted.

Low and high-grade endometrial stromal sarcomas (ESS) can be distinguished on a morphologic basis. Low-grade ESS is composed of oval cells that resemble normal proliferative-phase endometrial stroma, while the well-known high-grade ESS is composed of round cells growing in nests separated by delicate sinusoidal vasculature. Recurrent JAZF1 rearrangements have been reported to be most frequent in low-grade stromal sarcomas (up to 60%), while YWHAE rearrangements are characteristic of high-grade ESS. Herein, we report a case of a 45-yr-old woman with stage IA typical low-grade ESS who developed multiple abdominopelvic recurrences and lung metastases 15 mo after her primary tumor was resected. The unusual morphology (without high-grade areas) as well as the aggressive behavior of the tumor prompted molecular testing which showed YWHAE rearrangement in her abdominopelvic recurrence and her primary tumor. Five years after her primary tumor was resected, she developed scalp metastases with a typical morphology of a high-grade ESS associated with t(10;17) and died of her disease. Our case highlights the potential value of molecular testing in all low-grade ESS at time of initial diagnosis to stratify patients at higher risk for developing high-grade ESS with the goal of offering closer follow-up for early detection and treatment if transformation occurs.

Objectives Management of the axilla in breast cancer patients has evolved considerably since the introduction of the sentinel lymph node (SLN) biopsy in the 1990s. Several new clinical and technological developments in the last decade warrant special consideration due to their impact on pathology practice. Methods This review covers the SLN biopsy procedure, issues in the histopathologic and molecular diagnosis of the SLN, and most importantly, evidence from recent practice-changing clinical trials. Results ACOSOG Z0011, IBCSG 23-01, and AMAROS trials have shown that early-stage breast cancer patients who have limited metastatic involvement of the SLNs do not benefit from completion axillary dissections. Conclusions It is not necessary for pathologists to search for all small metastases to predict non-SLN involvement, regional recurrence, or death due to disease. Processing should be designed with the goal of detecting macrometastases. Multiple levels, routine immunohistochemistry, and molecular testing are not recommended.

Mucinous lesions of the breast include a variety of benign and malignant epithelial processes that display intracytoplasmic or extracellular mucin, including mucocelelike lesions, mucinous carcinoma, solid papillary carcinoma, and other rare subtypes of mucin-producing carcinoma. The most important diagnostic challenge is the finding of free-floating or stromal mucin accumulations for which the significance depends on the clinical, radiologic, and pathologic context. This article emphasizes the differential diagnosis between mucocelelike lesions and mucinous carcinoma, with a brief consideration of potential mimics, such as biphasic and mesenchymal lesions with myxoid stroma ("stromal mucin") and foreign material.

Background: Inflammatory breast cancer (IBC) is inoperable at presentation, thus neoadjuvant systemic therapy (NAS) is the primary treatment for this aggressive disease. Due to its rarity, patients (pts) with IBC are incorporated into NAS clinical trials for locally advanced breast cancer, making it difficult to extrapolate efficacy specifically for pts with IBC. A commonly used regimen for the treatment of HER2+ IBC includes docetaxel, carboplatin, pertuzumab (P) and trastuzumab (H), yet only 6% of pts enrolled in the clinical trial for this regimen had IBC. We sought to examine the efficacy of maximizing anti-HER2 therapy combined with minimal chemotherapy using the THP regimen specifically for pts with HER2+ IBC. Methods: Pts with newly diagnosed HER2+ IBC received NAS with 16 weeks (wks) of paclitaxel (T) 80mg/m2/wk, H (2mg/kg/wk) and P(420mg/kg/3wk) followed by modified radical mastectomy (MRM) on a phase II prospective study. All pts had 2 research breast biopsies (rbx) for correlative assays prior to and 1 wk after the P (840mg/kg) and H (4 mg/kg) loading dose. Pts who achieved a pCR (pathologic complete response) could opt out of adjuvant doxorubicin (A) 60 mg/m2 + cyclophosphamide (C) 600mg/m2 x 4; pts with residual disease received AC. All pts received post-mastectomy radiation and maintenance P (420mg) + H (6mg/kg) every 3 wks x 12. Adjuvant endocrine therapy was given per standard of care. Primary objective was pCR rate in the breast and axillary lymph nodes. Residual Cancer Burden (RCB) was assessed. Based upon a Simon two-stage design, this regimen would be declared worthy of further study if >7/27 pCR were observed (15% vs 40%; target α=0.039 power=0.90). The study was closed after 23/27 pts were enrolled due to slow accrual. Results: 20 pts were enrolled as of 12/2016, 18 completed NAS and MRM. All but 1 had stage III disease at presentation. 1 pt was lost to follow-up; 1 developed CNS metastasis during NAS and did not undergo MRM. The mean age was 49 years, 10 pts had ER/PR negative disease. 15 pts completed 16 wks of T, 4 had 15 wks and 1 had 13 wks. During NAS, there was no grade (gd) 4 toxicity; 6 episodes of gd 3 toxicity (2 related to treatment-diarrhea); and no gd 3 cardiac events. In the intent to treat analysis, 10/20 pts achieved pCR (50%; 90% CI 30-70%) and 6 had RCB-1 (30%). 5 pts with RCB-1 response had Conclusion: THP x 16wks is tolerable and effective NAS for HER2+ IBC, resulting in a high pCR rate with minimal toxicity. This study of NAS explored the benefit of maximizing HER2-directed therapy and minimizing chemotherapy and its associated toxicity. It has achieved its primary endpoint and will be used as the backbone NAS for HER2+ IBC, with future studies building upon this regimen. The result of this trial supports the benefit of clinical trials designed specifically for pts with IBC. Clinical trial information: NCT01796197. Citation Format: Overmoyer B, Regan M, Hu J, Nakhlis F, Dominici L, Lin NU, Freedman R, Morganstern DE, Partridge AH, Schlosnagle EJ, Hirshfield-Bartek J, Bellon J, Morikawa A, Harrison BT, Winer E. Weekly paclitaxel, pertuzumab and trastuzumab (TPH) neoadjuvant therapy for HER2 positive inflammatory breast cancer [abstract]. In: Proceedings of the 2017 San Antonio Breast Cancer Symposium; 2017 Dec 5-9; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2018;78(4 Suppl):Abstract nr P6-15-11.

Introduction: Non-classic lobular carcinoma in situ (NC-LCIS) is a rare pathologic entity which encompasses a variety of histologic diagnoses. As such its natural history, including upgrade rates to invasive cancer (IC) or ductal carcinoma in situ (DCIS) on excision, is poorly characterized. We sought to evaluate the risk of upgrade to IC or DCIS when NC-LCIS is diagnosed on core biopsy. Methods: After obtaining IRB approval, institutional pathology databases were searched for NC-LCIS core biopsy diagnoses (carcinoma in situ (CIS), carcinoma in situ with ductal and lobular features (CIS/DLF), pleomorphic LCIS (P-LCIS), variant LCIS (V-LCIS), LCIS with necrosis). Cases with a NC-LCIS core biopsy diagnosis and with available pathology results from subsequent surgery were included. Cases with known concurrent ipsilateral IC, DCIS and/or atypical ductal hyperplasia were excluded. Results: 107 cases with NC-LCIS in any pathology report were identified (1998-2016); 44 were excluded due to concurrent ipsilateral IC, the remaining 62 patients with 63 core biopsy diagnoses of NC-LCIS all underwent surgical excision and formed our study cohort. Median age was 56 years (range 43-83); 43 (68%) were postmenopausal. NC-LCIS was diagnosed on core biopsy for mammographic findings in 57 (90%) cases and for MRI findings in 6 (9%). All were BI-RADS 4 lesions; calcifications were the most common biopsy indication (50 (78%)). CIS/DLF was the most common term used for NC-LCIS (28 (44%)), followed by CIS (18 (29%)), V-LCIS (14 (22%)) and P-LCIS (3 (5%)). On core biopsy, 36/44 (82%) of NC-LCIS cases were E-cadherin negative, 38/41 (93%) were ER positive, and 6/34 (18%) were HER2 positive. IC and/or DCIS were diagnosed on subsequent surgery in 22 (33%) of patients, of which 14 (67%) were IC and 8 (18%) had DCIS only. LesionTotalE-cadherin negativeUpgraded, N (%)Invasive cancer, N (%)DCIS only, N (%)CIS188/10 (80%)3 (16%)2 (67%)1 (33%)CIS/DLF2819/23 (83%)12 (43%)7 (58%)5 (42%)P-LCIS31/1 (100%)3 (100%)2 (67%)1 (33%)V-LCIS148/10 (80%)4 (29%)3 (75%)1 (25%) Median IC size was 0.2 cm (0.06-1.1 cm). IC histology was ductal in n=4 (29%), lobular in n=7 (50%), and ductal and lobular in n=3 (21%). Among the 14 invasive lesions, 5 (36%) were grade I, 5 (36%) were grade II and 2(13%) were grade III, (grade was not reported for 2 remaining ICs); 12/14 (86%) were ER positive and 1/14 (7%) was HER2 positive; none had LVI or positive nodes. Among the 42 cases not upgraded, 13 (31%) had mastectomy, 9 (21%) had excision and radiation, 20 had excision only, all had negative margins. At median follow-up of 60 months (1-224 months), 1/20 patients treated with excision only was diagnosed with DCIS, 14 months after surgery for CIS/DLF on core biopsy. Conclusions: In this large series of NC-LCIS diagnosed on core biopsy, the upgrade rate to carcinoma was 33% supporting the recommendation for routine excision of these lesions. The cancers found at excision were all stage I and the majority were grade I or II. At a median follow-up of 60 months only 1/20 patients with pure NC-LCIS treated with excision alone developed a future ipsilateral cancer. Further study of the natural history of these rare lesions is warranted. Citation Format: Nakhlis F, Harrison BT, Lester SC, Hughes KS, Coopey SB, King TA. Evaluating the risk of upgrade to invasive breast cancer and/or DCIS on excision following a diagnosis of non-classic lobular carcinoma in situ [abstract]. In: Proceedings of the 2017 San Antonio Breast Cancer Symposium; 2017 Dec 5-9; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2018;78(4 Suppl):Abstract nr P5-22-01.

Context.—A review of amended pathology reports provides valuable information regarding defects in the surgical pathology process.Objective.—To review amended breast pathology reports with emphasis placed on interpretative errors and their mechanisms of detection.Design.—All amended pathology reports for breast surgical specimens for a 5-year period at a large academic medical center were retrospectively identified and classified based on an established taxonomy.Results.—Of 12 228 breast pathology reports, 122 amended reports were identified. Most (88 cases; 72%) amendments were due to noninterpretative errors, including 58 report defects, 12 misidentifications, and 3 specimen defects. A few (34 cases; 27.9%) were classified as misinterpretations, including 14 major diagnostic changes (11.5% of all amendments). Among major changes, there were cases of missed microinvasion or small foci of invasion, missed micrometastasis, atypical ductal hyperplasia overcalled as ductal carcinoma in situ, ductal carcinoma in situ involving sclerosing adenosis mistaken for invasive carcinoma, lymphoma mistaken for invasive carcinoma, and amyloidosis misdiagnosed as fat necrosis. Nine major changes were detected at interpretation of receptor studies and were not associated with clinical consequences. Three cases were associated with clinical consequences, and of note, the same pathologist interpreted the corresponding receptor studies.Conclusions.—Review of amended reports was a useful method for identifying error frequencies, types, and methods of detection. Any time that a case is revisited for ancillary studies or other reasons, it is an opportunity for the surgical pathologist to reconsider one's own or another's diagnosis.

Breast cancer has the second highest death toll in women worldwide, despite significant progress in early diagnosis and treatments. The main cause of death is metastatic disease. Matrix metalloproteinases (MMP) are required for the initial steps of metastasis, and have therefore been considered as ideal pharmacologic targets for antimetastatic therapy. However, clinical trials of MMP inhibitors were unsuccessful. These trials were conducted in patients with advanced disease, beyond the stage when these compounds could have been effective. We hypothesized that early treatment with a selective MMP inhibitor between the time of diagnosis and definitive surgery, the so-called “window-of-opportunity,” can inhibit metastasis and thereby improve survival. To investigate our hypothesis, we used the 4T1 mouse model of aggressive mammary carcinoma. We treated the animals with SD-7300, an oral inhibitor of MMP-2, -9, and -13, starting after the initial detection of the primary tumor. Seven days later, the primary tumors were excised and analyzed for MMP activity, and the SD-7300 treatment was discontinued. After 4 weeks, the animals were sacrificed and their lungs analyzed histologically for number of metastases and metastatic burden (metastases' area/lung section area). SD-7300 treatment inhibited 70% to 80% of tumor-associated MMP activity (P = 0.0003), reduced metastasis number and metastatic burden by 50% to 60% (P = 0.002 and P = 0.0082, respectively), and increased survival (92% vs. 66.7%; P = 0.0409), relative to control vehicle. These results show that treatment of early invasive breast cancer with selective MMP inhibitors can lower the risk of recurrence and increase long-term disease-free survival. Mol Cancer Ther; 15(10); 2370–7. ©2016 AACR.

A 52-year-old woman presented with a unilateral pleural effusion. Several weeks later, uterine bleeding, pelvic fullness, and bloating developed. Magnetic resonance imaging revealed a large pelvic mass. Diagnostic procedures were performed.

Background: The IMpassion130 study demonstrated prolonged overall survival when atezolizumab, a PD-L1 inhibitor, was added to nab-paclitaxel in PD-L1 positive patients with advanced triple negative breast cancer (TNBC). Approximately 40% of tumors were PD-L1 positive, utilizing a cutoff of ≥ 1% immune cell (IC) staining with the Ventana SP142 immunohistochemical (IHC) assay. The Food and Drug Administration (FDA) approved this assay as a companion test to determine patient eligibility for atezolizumab therapy. However, literature in lung cancer shows that pathologists have a high discordance in assessing PD-L1 on IC. The FDA companion test documentation for SP142 shows high inter-laboratory reproducibility with nearly 95% overall percent agreement (OPA) between 2 readers for 2 category scoring of IC (positive versus negative) in TNBC in a central laboratory. PD-L1 testing for breast cancer is now becoming widespread in pathology laboratories. The goal of this study was to assess concordance in PD-L1 scoring between 19 pathologists from 14 institutions examining the same 86 TNBC tissues stained with the SP142 and SP263 antibodies. We also present a new method to determine the minimum number for evaluators needed to estimate concordance between large numbers of readers as occurs in real life setting. Methods: Full tissue sections were stained exactly as prescribed on the label on the Ventana Benchmark with the SP142 and SP263 PD-L1 assays. Sixty-eight and 76 cases were evaluable respectively. Stained slides were scanned and digital files distributed to pathologists who independently scored cases as either negative (< 1% IC staining) or positive (≥ 1% IC staining) and estimated the % of IC staining for positive cases. We applied a method that we call Observers Needed to Evaluate Subjective Tests (ONEST). For any combination of pathologists, we can quantify the degree of overall agreement using the proportion of tissue samples upon which all selected pathologists agreed, which can lead to a plot of non-increasing trajectory of agreement as the number of pathologists increases. We computed and plotted the empirical estimate of the overall agreement with the 95% confidence interval (CI) from 1000 randomly selected permutations of the pathologists. Results: PD-L1 was interpreted as positive with SP263 in an average of 78% of cases compared to 58% with the SP142 assay (p Citation Format: Emily Suzanne Reisenbichler, Gang Han, Vasiliki Pelekanou, Vesal Yaghoobi, Fahad S Ahmed, Andrew Bellizzi, Veerle Bossuyt, Jane Brock, Kimberly Cole, Oluwole Fadare, Omar Hameed, Krisztina Hanley, Beth T Harrison, M G Kuba, Amy Ly, Dylan Miller, Mirna Podoll, Anja C Roden, Mary A Sanders, Kamaljeet Singh, Shi Wei, Hannah Wen, Lajos Pusztai, David L Rimm. Prospective multi-institutional evaluation of pathologist assessment of PD-L1 assays in triple negative breast cancer [abstract]. In: Proceedings of the 2019 San Antonio Breast Cancer Symposium; 2019 Dec 10-14; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2020;80(4 Suppl):Abstract nr PD5-01.

Context Patients choosing to retain the nipple when undergoing therapeutic or prophylactic mastectomy are at risk for cancers arising at that site. Objective To identify cases of invasive carcinoma arising within the nipple and to investigate their clinical, imaging, biologic, and staging features. Design Carcinomas were identified by prospective review of surgical and consult cases at 4 hospitals. Results The 24 patients identified presented with symptoms related to the nipple. Mammography did not detect the cancer in most cases. Ten patients (42%) had skin changes from ductal carcinoma in situ involving nipple skin (Paget disease), with small foci of invasion into the dermis, and 6 of those 10 carcinomas (60%) stained positive for human epidermal growth factor receptor 2 (HER2). The remaining 14 patients (58%) presented with a nipple mass or with skin changes. These were larger invasive carcinomas of both ductal and lobular types. Only 2 of those 14 carcinomas (14%) were HER2+. Three of 15 patients (20%) undergoing lymph node biopsy had a single metastasis. No patients have had recurrent disease. Conclusions Rare, invasive, primary nipple carcinomas typically present as subtle nipple thickening or an exudative crust on the skin. Imaging studies are often nonrevealing. A variety of histologic and biologic types of carcinomas occur, similar to cancers arising deeper in the breast. Although the carcinomas invaded into the dermis, some with skin ulceration, the likelihood of lymph node metastasis was no higher than carcinomas of similar sizes. Patients who choose to preserve their nipple(s) should be aware of the possibility of breast cancer arising at that site and to bring any observed changes to the attention of their health care providers.

Our aim was to investigate whether molecular classification can be used to refine prognosis in grade 3 endometrial endometrioid carcinomas (EECs). Grade 3 EECs were classified into 4 subgroups: p53 abnormal, based on mutant-like immunostaining (p53abn); MMR deficient, based on loss of mismatch repair protein expression (MMRd); presence of POLE exonuclease domain hotspot mutation (POLE); no specific molecular profile (NSMP), in which none of these aberrations were present. Overall survival (OS) and recurrence-free survival (RFS) rates were compared using the Kaplan-Meier method (Log-rank test) and univariable and multivariable Cox proportional hazard models. In total, 381 patients were included. The median age was 66 years (range, 33 to 96 y). Federation Internationale de Gynecologie et d'Obstetrique stages (2009) were as follows: IA, 171 (44.9%); IB, 120 (31.5%); II, 24 (6.3%); III, 50 (13.1%); IV, 11 (2.9%). There were 49 (12.9%) POLE, 79 (20.7%) p53abn, 115 (30.2%) NSMP, and 138 (36.2%) MMRd tumors. Median follow-up of patients was 6.1 years (range, 0.2 to 17.0 y). Compared to patients with NSMP, patients with POLE mutant grade 3 EEC (OS: hazard ratio [HR], 0.36 [95% confidence interval, 0.18-0.70]; P=0.003; RFS: HR, 0.17 [0.05-0.54]; P=0.003) had a significantly better prognosis; patients with p53abn tumors had a significantly worse RFS (HR, 1.73 [1.09-2.74]; P=0.021); patients with MMRd tumors showed a trend toward better RFS. Estimated 5-year OS rates were as follows: POLE 89%, MMRd 75%, NSMP 69%, p53abn 55% (Log rank P=0.001). Five-year RFS rates were as follows: POLE 96%, MMRd 77%, NSMP 64%, p53abn 47% (P=0.000001), respectively. In a multivariable Cox model that included age and Federation Internationale de Gynecologie et d'Obstetrique stage, POLE and MMRd status remained independent prognostic factors for better RFS; p53 status was an independent prognostic factor for worse RFS. Molecular classification of grade 3 EECs reveals that these tumors are a mixture of molecular subtypes of endometrial carcinoma, rather than a homogeneous group. The addition of molecular markers identifies prognostic subgroups, with potential therapeutic implications. This study was funded in part by the Dutch Cancer Society (KWF-UL2012-5719) (Dr. Bosse, Dr. Nout). This study was funded in part through the NIH/NCI Support Grant P30 CA008748 (Dr. Abu-Rustum, Dr. Levine, Dr. Soslow).

This review summarizes the literature from the last 5 years regarding atypical ductal hyperplasia (ADH), atypical lobular hyperplasia (ALH), classic lobular carcinoma in situ (C-LCIS), and non-classic LCIS (NC-LCIS). ADH, ALH, and C-LCIS are well-established markers of increased breast cancer risk. Recent studies suggest the possibility of observation for select cases of ADH diagnosed on core biopsy; however, guidelines support routine excision. In contrast, accumulating data support observation for ALH and C-LCIS on core biopsy with radiographic–pathologic concordance. Data on the natural history of pure NC-LCIS remain limited; however, when NC-LCIS is diagnosed on core biopsy, routine excision is warranted. ALH and C-LCIS on core biopsy should be reviewed for concordance to determine the need for excision; independent of surgical excision, all warrant counseling regarding increased future breast cancer risk. Current guidelines support routine excision for ADH and NC-LCIS on core biopsy. The natural history of NC-LCIS remains poorly defined.

Endometriosis is a common disorder that causes significant morbidity from dysmenorrhea, pelvic pain, and subfertility. Establishment of a definitive diagnosis has important therapeutic implications; however, only approximately 50% of biopsies of laparoscopically suspicious areas provide a diagnosis of endometriosis. Histologic criteria for diagnosis require the presence of endometrial glands or endometrial-type stroma. We hypothesize that other frequently present, but nondiagnostic, histologic features of endometriosis suggest its presence in patients with nondiagnostic peritoneal biopsies. We performed a retrospective clinicopathologic study of morphologic and immunohistochemical features that may improve the histologic diagnosis of endometriosis on laparoscopic peritoneal biopsies. We compared diagnostic (n=88) and nondiagnostic (n=54) peritoneal biopsies from pathologically confirmed endometriosis cases with negative peritoneal biopsies (n=84) from early-stage gynecologic cancer cases. Statistical analysis utilized the Fisher exact test. Multiple morphologic features were significantly increased in nondiagnostic biopsies from patients with endometriosis in comparison with those from negative controls, including foamy macrophages (P=0.0001) and submesothelial stromal clusters (SSCs) (P=0.0008). SSCs ranged from subtle aggregates of spindle cells to nodules of whorled spindle cells with small vessels and extravasated red blood cells resembling stromal endometriosis. Immunohistochemical studies confirmed that ER and CD10-positive SSCs were present in a greater proportion of both nondiagnostic and diagnostic peritoneal biopsies and at a greater number of lesions per biopsy. The overall histologic detection rate of peritoneal biopsies for endometriosis was 62.0%, and inclusion of SSCs with or without foamy macrophages in the diagnostic criteria appreciably increased this rate to between 72.5% and 76.8%. We describe SSCs, which appear to be an early or less developed form of stromal endometriosis, and, when included in the diagnostic criteria, improve the histologic detection rate of endometriosis in peritoneal biopsies.

Massive ovarian edema is a rare disorder in which there is marked accumulation of interstitial fluid in the stroma of the ovary. Grossly, the involved ovary is an enlarged solid mass with a smooth tan-white surface, easily confused with a neoplasm. Microscopically, it features diffuse interstitial edema sparing follicles and outer cortex, dilated lymphatic vessels, thick-walled veins, fibromatosis, and luteinized stromal cells. It is believed that massive ovarian edema arises from interference in lymphatic drainage and venous return of the ovary secondary to partial torsion among other etiologies. Herein we provide the first description of unilateral ovarian edema in association with a large leiomyoma in the ipsilateral broad ligament. It is important to recognize the various presentations of this benign entity and to consider it in the differential diagnosis of an adnexal mass in a reproductive age woman.

Background Inflammatory breast cancer (IBC) is an understudied form of breast cancer (BC). The incidence of HER2-positive disease in IBC is 2-fold greater than that in non-IBC. Several studies evaluating dual-HER2 blockade in HER2-positive BC have demonstrated an association of specific gene expression signatures with response. Those analyses were based on pretreatment tumor characteristics and did not focus specifically on IBC. We used RNA-Seq to elucidate the impact of short term neoadjuvant dual-HER2 blockade on IBC transcriptomic profile and to identify early predictors of response. Methods We analyzed fresh frozen tumor samples prospectively obtained from 23 patients (pts) with HER2-positive IBC, treated at a single institution in a phase 2 trial (NCT01796197) with neoadjuvant trastuzumab, pertuzumab (HP) and paclitaxel for 16 weeks (wk). Breast biopsies were performed at baseline (D1) and 1 wk later (D8) after a single dose of dual blockade with HP before adding paclitaxel. Primary endpoint was pathologic complete response (pCR) defined as no evidence of invasive disease in breast or lymph nodes. Tumors from D1 and D8 were used for RNA-Seq analysis and assessment of tumor-infiltrating lymphocytes (TILs) and CelTIL score. Results Paired breast tumor biopsies (D1, D8) were obtained in all pts; 2 pts did not have surgery. In the intent-to-treat analysis, 10/23 (43%) pts achieved a pCR. Across all metrics, D8 biopsies were significantly better predictors of response than D1 (p-value: 1.0X10-15). Upregulation of immune signatures by RNA-Seq was observed at D1 and D8. D8 biopsies showed a greater upregulation of anti-tumor immunity and changes in multiple signalling pathways. Neither TILs nor CelTIL were associated with pCR. Conclusions We identified an accurate predictor of response based on transcriptomic profiling by RNAseq, following a single dose of neoadjuvant dual-HER2 blockade in HER2-positive IBC. It outperforms a similar predictor constructed on a pretreatment profile in the same cohort. Assessing early-changes in gene expression level by RNA-seq following one dose of treatment may provide insights for the molecular mechanisms underlying response or resistance to anti-HER2 therapy. Clinical trial identification NCT01796197. Legal entity responsible for the study Dana-Farber Cancer Institute. Funding Genentech, Inc and the Inflammatory Breast Cancer (IBC) Network. Disclosure S. Pernas: Travel / Accommodation / Expenses: Roche; Advisory / Consultancy: Polyphor. S. Goel: Advisory / Consultancy, Research grant / Funding (institution): Eli Lilly; Advisory / Consultancy, Research grant / Funding (institution): Novartis; Advisory / Consultancy: G1 Therapeutics; Research grant / Funding (institution): Merck. J.L. Guerriero: Advisory / Consultancy, Research grant / Funding (institution): Glaxo-Smith Kline; Research grant / Funding (self): Eli Lilly. E.A. Mittendorf: Advisory / Consultancy: Amgen; Advisory / Consultancy, Research grant / Funding (institution): AstraZeneca; Advisory / Consultancy, Research grant / Funding (institution): Genentech; Advisory / Consultancy: Genomic Health; Advisory / Consultancy: Merck; Advisory / Consultancy: Peregrine Pharmaceuticals; Advisory / Consultancy, Research grant / Funding (institution): Sellas Lifesciences; Advisory / Consultancy: Tapimmune. B. Overmoyer: Research grant / Funding (institution): Genentech; Research grant / Funding (institution): Incyte; Research grant / Funding (institution): Eisai. All other authors have declared no conflicts of interest.

Sclerosing adenosis, sclerosing lesions, microglandular adenosis, and mucocele-like lesions are benign lesions that may mimic invasive carcinoma on routine histology. Adenosis and sclerosing lesions are small glandular proliferations that may resemble well-differentiated invasive ductal or tubular carcinoma, whereas mucocele-like lesions may be confused with mucinous carcinoma. It may be especially difficult to recognize these lesions in the limited core needle biopsy sample, and therefore, it is important to maintain a low threshold for diagnostic work-up. Immunohistochemical studies for myoepithelial cell markers facilitate the correct diagnosis in challenging cases. However, a notable exception, microglandular adenosis, lacks myoepithelial cells, and must be distinguished from well-differentiated invasive carcinoma by its S-100 protein immunoreactivity and triple negative phenotype.

Sarcomatoid carcinoma of the urinary bladder is an unusual malignancy composed of both carcinomatous and sarcomatous components. It is an aggressive tumor that presents at an advanced stage and confers a much poorer prognosis than conventional urothelial carcinoma. The proper nomenclature and histogenesis of these tumors have been subjects of debate for some time. There is an emerging consensus that sarcomatoid carcinoma is the most appropriate term for these neoplasms. The recent World Health Organization classification has applied this term to all tumors showing morphologic and/or immunologic evidence of both malignant epithelial and mesenchymal differentiation. Such tumors have been postulated to represent either multiclonal collision tumors or monoclonal cancers with divergent differentiation; recent molecular studies favor the latter theory. In this study, we discuss the nomenclature, clinical features, pathology, differential diagnosis, molecular genetics, and histogenesis of sarcomatoid carcinoma. We emphasize the importance of molecular genetic studies in providing insight into the histogenesis of this neoplasm. Sarcomatoid carcinoma seems to represent the final common pathway of urothelial carcinoma dedifferentiation.

Intravascular large B-cell lymphoma (IVLBCL) is a rare type of extranodal diffuse large B-cell lymphoma (NHL) characterized by the presence of neoplastic lymphocytes only in the lumina of small vessels and capillaries. Although studies have shown an association of IVLBCL with other lymphomas, its relationship with mantle cell lymphoma has not been reported. Here we report a rare case of a 76 year-old male with intravascular transformation of mantle cell lymphoma in the adrenal glands. Histopathological examination of the adrenal mass biopsy revealed two cell populations within the fibrovascular tissue – a diffuse and infiltrative small lymphoid cell population and an unexpected large neoplastic cell population. Immunohistochemistry (IHC) for the small lymphoid cells are positive for CD5, CD20, and cyclin D1, with the t(11;14)(q13;q32) chromosomal rearrangement on cytogenetic analysis by interphase fluorescence in situ hybridization (FISH), characteristic for mantle cell lymphoma. The large cells are positive for CD5, CD20 and CD79a and negative for cyclin D1 on IHC, demonstrating exclusive localization within small capillaries by CD34 staining, evident of IVLBCL. In addition, FISH analysis revealed that the large cells also have the t(11;14)(q13;q32) mantle cell lymphoma rearrangement. To our knowledge, the present study provides the first reported case of IVLBCL transformation from mantle cell lymphoma and supports the hypothesis that IVLBCL may arise by transformation from other lymphomas.