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PurposeSeveral pathologic staging systems characterize residual tumor in patients undergoing neoadjuvant chemotherapy for breast cancer. Pathologic complete response (pCR) is now accepted by the Food and Drug Administration as an endpoint for granting accelerated drug approval. Two other systems of post-neoadjuvant pathologic tumor staging-residual cancer burden (RCB) and the American Joint Committee on Cancer post-neoadjuvant therapy staging system (yAJCC)-have been developed to characterize residual tumors when patients do not achieve pCR. The optimal system and the ways in which these systems complement each other have not been fully determined.MethodsUsing data from the I-SPY 1 TRIAL, we compared pCR, RCB, and yAJCC as predictors of early recurrence-free survival (RFS) to identify ways to improve post-neoadjuvant pathologic evaluation.ResultsAmong 162 patients assessed, pCR identified patients at lowest risk of recurrence, while RCB and yAJCC identified patients at highest risk. Hormone-receptor (HR) and HER2 subtypes further improved risk prediction. Recursive partitioning indicated that triple-negative or HER2+ patients with yAJCC III or RCB 3 have the highest recurrence risk, with an RFS of 27%. Our analysis also highlighted discrepancies between RCB and yAJCC stratification: 31% of patients had discrepant RCB and yAJCC scores. We identified differential treatment of lymph node involvement and tumor cellularity as drivers of these discrepancies.ConclusionsThese data indicate that there is benefit to reporting both RCB and yAJCC for patients in order to identify those at highest risk of relapse.

Neoadjuvant systemic therapy (NAST) provides the unique opportunity to assess response to treatment after months rather than years of follow-up. However, significant variability exists in methods of pathologic assessment of response to NAST, and thus its interpretation for subsequent clinical decisions. Our international multidisciplinary working group was convened by the Breast International Group-North American Breast Cancer Group (BIG-NABCG) collaboration and tasked to recommend practical methods for standardized evaluation of the post-NAST surgical breast cancer specimen for clinical trials that promote accurate and reliable designation of pathologic complete response (pCR) and meaningful characterization of residual disease. Recommendations include multidisciplinary communication; clinical marking of the tumor site (clips); and radiologic, photographic, or pictorial imaging of the sliced specimen, to map the tissue sections and reconcile macroscopic and microscopic findings. The information required to define pCR (ypT0/is ypN0 or ypT0 yp N0), residual ypT and ypN stage using the current AJCC/UICC system, and the Residual Cancer Burden system were recommended for quantification of residual disease in clinical trials.

* Context.--Immunohistochemical expression of mismatch repair (MMR) protein is a well-accepted method for routine screening for Lynch syndrome with relatively high sensitivity and specificity. Occasionally, however, immunohistochemistry (IHC) can yield an equivocal result with poor reproducibility and the potential for misdiagnosis. Objective.--To determine the frequency and significance of indeterminate MMR IHC expression in patients routinely screened for Lynch syndrome and correlation with germline mutation studies. Design.--Semiquantitative scoring of MMR IHC was performed by image analysis in 479 cases, of which 380 were colorectal and 99 endometrial cancer. Scores of 10% or more, less than 10%, and 0% were used as cutoffs for retained, indeterminate, and loss of expression, respectively. Negative and indeterminate IHC results were confirmed by mutational studies. Results.--Four hundred eighteen of 479 cases (87.2%) were reported as retained expression, 45 (9.3%) as loss of expression, and 16 (3.3%) as indeterminate expression. Fifteen of 45 (33.3%) and 8 of 16 (50%) with loss and indeterminate expression, respectively, were found to have Lynch syndrome by germline studies. The overall frequency of Lynch syndrome in our patient population was 4.8% (23 of 479), and 34.7% of these (8 of 23) were associated with indeterminate IHC expression. In the indeterminate group, MLH1 germline mutation was the most frequent (6 of 13; 46.2%), followed by MSH6 (4 of 13; 30.7%). Conclusions.--Our findings provide further evidence that indeterminate IHC should be further investigated for possible MMR germline mutation. Guidelines for interpretation of MMR IHC and the establishment of more objective criteria for defining indeterminate results are important to improve the sensitivity and specificity of the IHC assay. (Arch Pathol Lab Med. 2019;143:1225-1233; doi: 10.5858/arpa.2018-0201-OA), Lynch syndrome (LS) is an autosomal-dominant cancer predisposition syndrome caused by germline mutation of DNA of the mismatch repair (MMR) genes MLH1, MSH2, MSH6, and PMS2. Two percent to 4% [...]

* Context.--The American Society of Clinical Oncology/ College of American Pathologists proposed several recommendations for human epidermal growth factor receptor 2 (HER2) test standardization. One suggestion was that image analysis (IA) could be useful for scoring of HER2/ neu immunohistochemistry. The utilization of IA in a real-world practice in a large cohort of cases has not been previously reported. Objectives.--To compare HER2/neu quantification by IA with gene amplification by fluorescence in situ hybridization (FISH); to determine sensitivity, specificity, and concordance rates with the FISH assay; and to determine association between HER2 status with estrogen receptor (ER), progesterone receptor (PR), and Ki-67 expression. Design.--We evaluated HER2 results performed by immunohistochemistry and FISH in conjunction with ER, PR, and Ki-67 in 3093 invasive breast cancer cases from 2002 to 2011. Results.--The overall concordance between immunohistochemistry and FISH was 87.3% (1768 of 2026). When analyzed by year, there was an improvement in the positive concordance rate from 49.4% (44 of 89) to 95.0% (57 of 60) (P < .001) The negative concordance rate was at least 95% with a median false-negative rate of 1.5%. In the FISH+ group, amplification ratio showed significant correlation with IA scores (P < .001). Positive versus negative HER2 status was associated with lower ER and PR levels (P < .001) and higher Ki-67 expression (P < .001). Conclusion.--Scoring of HER2/neu by IA was associated with high false-positive rates before 2008. Improvement in concordance rate after 2008 may be due to proper tissue handling, improved HER2/neu scoring by IA, and assay standardization. (Arch Pathol Lab Med. 2015; 139:922-928; doi: 10.5858/arpa.2014-0127-OA), The HER2 is a member of the HER family of transmembrane receptors with tyrosine kinase activity encoded by the HER2/neu gene. (1) Approximately 15% to 25% of invasive breast cancers [...]

In this article, we report a very rare case of secondary angiosarcoma in a young woman with no prior history of breast cancer who had bilateral prophylactic mastectomies with autologous reconstruction due to a strong family history of breast cancer and BRCA1 gene variant of uncertain significance. The surgery was complicated by recurrent fat necrosis requiring several excisions and additional reconstruction followed by the development of localized lymphedema and subsequent angiosarcoma in the reconstructed breast 10 years later. The angiosarcoma was high grade with prominent epithelioid features associated with abundant tumor-infiltrating lymphocytes. Amplification of C-MYC locus 8q21.24 was demonstrated by fluorescence in situ hybridization study. We postulate that chronic trauma from several surgeries including tissue hypoxia and impaired lymphatic drainage may have provided a milieu for angiogenesis and mutagenic transformation. Amplification of C-MYC locus 8q21.24 was most likely a strong oncogenic driver of angiosarcoma. To the best of our knowledge, this is the first report of its kind in the literature. [ABSTRACT FROM AUTHOR]