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Background: The pathogenesis of lymph node metastases in preinvasive breast cancer – ductal carcinoma in situ (DCIS) – remains controversial. The one-step nucleic acid amplification (OSNA) assay is a novel molecular method that can assess a whole node and detect clinically relevant metastases. In this retrospective cohort study, we determined the performance of the OSNA assay in DCIS and the pathogenesis of node-positive DCIS.Methods: The subjects consisted of 623 patients with DCIS who underwent sentinel lymph node (SN) biopsy. Of these, 2-mm-sectioned nodes were examined using frozen-section (FS) histology in 338 patients between 2007 and 2009, while 285 underwent OSNA whole node assays between 2009 and 2011. The SN-positivity rate was compared between cohorts, and the characteristics of OSNA-positive DCIS were investigated.Results: The OSNA detected more cases of SN metastases than FS histology (12 out of 285, 4.2% vs 1 out of 338, 0.3%). Most of the metastases were micrometastases. The characteristics of high-risk DCIS (i.e., mass formation, size, grade, and comedo) and preoperative breast biopsy (i.e., methods or time to surgery) were not valid for OSNA assay–positive DCIS.Conclusion: The OSNA detects more SN metastases in DCIS than FS histology. Further examination of the primary tumours and follow-up of node-positive DCIS are needed to elucidate the pathogenesis. [ABSTRACT FROM AUTHOR]

Intratumoral heterogeneity within individual breast tumors is a well-known phenomenon that may contribute to drug resistance. This heterogeneity is dependent on several factors, such as types of oncogenic drivers and tumor precursor cells. The purpose of our study was to engineer a mouse mammary tumor model with intratumoral heterogeneity by using defined genetic perturbations. To achieve this, we used mice with knockout (-/-) of Ink4a/Arf, a tumor suppressor locus; these mice are known to be susceptible to non-mammary tumors such as fibrosarcoma. To induce mammary tumors, we retrovirally introduced an oncogene, HRAS(G12V), into Ink4a/Arf−/− mammary cells in vitro, and those cells were inoculated into syngeneic mice mammary fat pads. We observed 100% tumorigenesis. The tumors formed were negative for estrogen receptor, progesterone receptor and HER2. Further, they had pathological features similar to those of human triple-negative breast cancer (TNBC) (for example, pushing borders, central necrosis). The tumors were found to be heterogeneous and included two subpopulations: CD49f− quiescent cells and CD49f+cells. Contrary to our expectation, CD49f− quiescent cells had high tumor-initiating potential and CD49f+cells had relatively low tumor-initiating potential. Gene expression analysis revealed that CD49f− quiescent cells overexpressed epithelial-to-mesenchymal transition-driving genes, reminiscent of tumor-initiating cells and claudin-low breast cancer. Our animal model with intratumoral heterogeneity, derived from defined genetic perturbations, allows us to test novel molecular targeted drugs in a setting that mimics the intratumoral heterogeneity of human TNBC. [ABSTRACT FROM AUTHOR]

Background:For patients with breast cancer treated with preoperative chemotherapy, residual tumour burden in lymph nodes is the strongest prognostic factor. However, conventional pathological examination has limitations that hinder the accurate and reproducible measurement. The one-step nucleic acid amplification (OSNA) assay is a novel molecular method for detecting nodal metastasis. In this prospective multicentre trial, we assessed the performance of the OSNA assay in detecting nodal metastasis after chemotherapy.Methods:In total, 302 lymph nodes from 80 breast cancer patients who underwent axillary dissection after chemotherapy were analysed. Each node was cut into two or four slices. One piece or alternate pieces were evaluated by pathology, and the other(s) were examined using the OSNA assay. The results of the two methods were compared. Stromal fibrosis, histiocytic aggregates, and degenerated cancer cells were regarded as chemotherapy-induced histological changes.Results:The overall accuracy, sensitivity, and specificity of the OSNA assay compared with the reference pathology were 91.1%, 88.3%, and 91.7%, respectively. Of the 302 lymph nodes, 66 (21.9%) exhibited chemotherapy-induced histology. For these nodes, the accuracy, sensitivity, and specificity were 90.9%, 88.9%, and 93.3%, respectively.Conclusion:The OSNA assay can detect the residual tumour burden as accurately as conventional pathology, although chemotherapy-induced histological changes are present. [ABSTRACT FROM AUTHOR]

Background: The one-step nucleic acid amplification (OSNA) assay is a molecular-based lymph-node metastasis detection procedure that can assess a whole node and yields semi-quantitative results for the detection of clinically relevant nodal metastases. We aimed to determine the performance of the OSNA assay as an accurate nodal staging tool in comparison with routine histological examination.Methods: Subjects comprised 183 consecutive patients with pT1-2 breast cancer who underwent axillary dissection after positive sentinel-node (SN) biopsy with the OSNA assay. Of these, for non-SN evaluation, 119 patients underwent OSNA assay evaluation, whereas 64 had single-section histology. We compared the detection rates of non-SN metastasis and upstaging rates from the SN stage according to the American Joint Committee on Cancer staging between the OSNA and histology cohorts.Results: OSNA detected more cases of non-SN metastases than histology (OSNA 66/119, 55.5% vs histology 13/64, 20.3%; P<0.001), particularly micrometastases (36/119, 30.3% vs 1/64, 1.6%; P<0.001). Total upstaging rates were similar in both cohorts (20/119, 16.8% vs 9/64, 14.1%, P=0.79).Conclusion: OSNA detects a far greater proportion of non-SN micrometastases than routine histological examination. However, upstaging rates after axillary dissection were not significantly different between both cohorts. Follow-up of the OSNA cohort is required to determine its clinical relevance. [ABSTRACT FROM AUTHOR]

We examined the validity of the St Gallen algorithm for Japanese breast cancer patients and sought the optimal indications of endocrine monotherapy as adjuvant systemic treatment. According to the 2005 St Gallen algorithm, endocrine responsiveness (responsive, uncertain, or non-responsive) and recurrence risk (low, intermediate, or high) were assessed in 436 invasive breast cancer patients, who underwent surgery and adjuvant therapy of tamoxifen alone in 1982–1993. Furthermore, intermediate-risk patients were divided into three groups based on lymph node metastasis and number of risk factors as follows: Group A, negative lymph node metastasis and one risk factor; Group B, negative lymph node metastasis and two to five risk factors; and Group C, positive lymph node metastasis. Cumulative 10-year recurrence-free survival (RFS) rates of each type were calculated. Recurrence-free survival was as follows: endocrine responsiveness; responsive: 86.0%, uncertain: 79.5%, non-responsive: 72.4%, risk category; low: 93.3%, intermediate: 84.0%, high: 59.6%, intermediate-risk patients; Group A: 93.5%, Group B: 88.2%, and Group C: 75.0%. In conclusion, patient classification based on St Gallen algorithm appears valid in Japanese breast cancer patients. Endocrine monotherapy may be sufficient as adjuvant treatment in the intermediate-risk patients, in which only one risk factor was present without any metastatic involvement in lymph node.British Journal of Cancer (2007) 97, 654–658. doi:10.1038/sj.bjc.6603916 www.bjcancer.com Published online 28 August 2007 [ABSTRACT FROM AUTHOR]

Abstract Background Acquisition of drug-resistance in cancer has led to treatment failure, however, their mechanisms have not been clarified yet. Recent observations indicated that aberrant expressed microRNA (miRNA) caused by chromosomal alterations play a critical role in the initiation and progression of cancer. Here, we performed an integrated genomic analysis combined with array-based comparative hybridization, miRNA, and gene expression microarray to elucidate the mechanism of drug-resistance. Results Through genomic approaches in MCF7-ADR; a drug-resistant breast cancer cell line, our results reflect the unique features of drug-resistance, including MDR1 overexpression via genomic amplification and miRNA-mediated TP53INP1 down-regulation. Using a gain of function study with 12 miRNAs whose expressions were down-regulated and genome regions were deleted, we show that miR-505 is a novel tumor suppressive miRNA and inhibits cell proliferation by inducing apoptosis. We also find that Akt3, correlate inversely with miR-505, modulates drug sensitivity in MCF7-ADR. Conclusion These findings indicate that various genes and miRNAs orchestrate to temper the drug-resistance in cancer cells, and thus acquisition of drug-resistance is intricately controlled by genomic status, gene and miRNA expression changes.

Abstract Background The impact of sentinel lymph node biopsy on breast cancer mimicking ductal carcinoma in situ (DCIS) is a matter of debate. Methods We studied the rate of occurrence of sentinel lymph node metastasis in 255 breast cancer patients with pure DCIS showing no invasive components on routine pathological examination. We compared this to the rate of occurrence in 177 patients with predominant intraductal-component (IDC) breast cancers containing invasive foci equal to or less than 0.5 cm in size. Results Most of the clinical and pathological baseline characteristics were the same between the two groups. However, peritumoral lymphatic permeation occurred less often in the pure DCIS group than in the IDC-predominant invasive-lesion group (1.2% vs. 6.8%, p = 0.002). One patient (0.39%) with pure DCIS had two sentinel lymph nodes positive for metastasis. This rate was significantly lower than that in patients with IDC-predominant invasive lesions (6.2%; p < 0.001). Conclusions Because the rate of sentinel lymph node metastasis in pure DCIS is very low, sentinel lymph node biopsy can safely be omitted.

Abstract Background The impact of skin invasion in node negative breast cancer is uncertain. Methods We determined the prognosis in 97 node negative breast cancer patients (case group) who had tumors with skin invasion. Then we compared these patients with 4500 node negative invasive breast cancer patients treated surgically in the same period. Results Patients with skin invasion tended to be older, had more invasive lobular carcinoma and larger tumor size, and were less likely to have breast conserving surgery than those in the control group. The 5-year disease-free survival rate in the case group was 94.0%. There was no significant difference in the 10-year disease-specific overall survival rates in terms of skin invasion in node negative patients (90.7% in the case group, 92.9% in the control group; p = 0.2032). Conclusion Results suggest that skin invasion has no impact on survival in node negative invasive breast cancer patients. The adjuvant regimens which the individual institute applies for node negative breast cancer should be used regardless of skin invasion.

Background: The OSNA (One Step Nucleic acid Amplification) assay is a semi-automated lymph node examination method using molecular biological technique. The OSNA assay has been validated for breast cancer patients without receiving preoperative systemic therapy (PST) by several clinical studies and has currently become more popular as sentinel lymph node (SLN) examination method with the following two main advantages; 1) to allow examination of the whole portion of a node, 2) to allow intraoperative judgment of metastasis positive or negative. However, the feasibility of the OSNA assay in breast cancer patients treated by PST has never been confirmed. In this multi-central clinical study, we compared the judgments of the OSNA assay and of pathological examination on lymph nodes dissected after receiving PST to evaluate the performance of the OSNA assay. Material & Methods: Three hundred two nodes dissected from the 80 breast cancer patients who received PST were examined. Each lymph node was divided at 2mm intervals and the slices were alternately applied to the OSNA assay and pathological examination with H&E staining and CK19 immunohistochemical staining of permanent-section. In pathological examination, judgments of metastasis positive or negative were determined by one central-review pathologist according to the criteria of AJCC 7th edition ("positive" if >0.2mm metastases were detected). Result: The overall concordance rate between the OSNA assay and pathological examination was 91.1% (275/302) with sensitivity of 88.3% (53/60) and specificity of 91.7% (222/242) (Table). These results are very similar to those of the Japanese clinical validation study in breast cancer patients without receiving PST which was conducted by the almost same protocol (Tamaki Y, et al. Clin Cancer Res, 2009, 15: 2879-2884). Conclusion & Discussion: These results indicate the OSNA assay can be applicable for breast cancer patients after receiving PST as well as breast cancer patients without receiving PST. The OSNA assay will enable to examine the whole portion of nodes, leading to more detection of metastases (especially micrometastases) and more exact nodal staging for breast cancer patients treated by PST. Also, for the patients who receive sentinel lymph node biopsy after PST, the OSNA assay will be useful as intraoperative examination method of SLNs because it is expected to provide more correct judgments than current intraoperative methods such as frozen-section or touch-print cytology. [ABSTRACT FROM AUTHOR]

Background: The standardized assessment of Ki-67 labeling index (LI) plays pivotal roles in identifying the patients (pts) with primary breast cancer who could benefit from systemic chemotherapy, in particular among pts with estrogen receptor(ER)-positive cancers. Therefore, in this study, we evaluated the inter-observer concordance of the assessment of Ki-67 LI in archival materials. Methods: Six surgical pathologists specializing in breast pathology from different Japanese institutions participated in this study. All slides were prepared from archival tissues of breast cancer fixed in 10% buffered formalin for 24 hours in a single institution (KU). Three independent studies were conducted. Study 1) Six consecutive slides were prepared from 5 cases. A slide from each case was stained with MIB-1 (DAKO, Denmark) in each institution according to their routine methods. Total of 30 stained slides were assessed for Ki-67 LI by each pathologist using two different modes of assessment. One is the scoring system in which the rate of positive cells was scored from 1 (0-9 %) to 10 (90-100%) without counting the cell number. The second one is the counting system in which approximately 1000 cells in total were counted in the hot spots and the positive rate was calculated. Study 2) Twenty tumors with Ki-67 LI ranging from 5 to 25 (15 ± 10) %, stained in a single institution (KU) were assessed by each pathologist by the counting system. Study 3) In order to avoid variations by assessment in varied microscopic fields and to further evaluate the variation of threshold of immunointensity interpreted as positive by different pathologists, fifteen printed photographs of Ki-67-stained slides were sent and assessed for Ki-67 LI by each participating breast pathologist. Results: Study 1) The counting system demonstrated a better correlation of Ki-67 LI among six pathologists than the scoring system {the intraclass correlation coefficient (ICC), 0.66 (95% confidence interval 0.52-0.78) for the counting system, 0.57 (0.42-0.72) for the scoring system}. The two assessment systems showed a moderate correlation {ICC, 0.68 (0.60-0.75)}. Study 2) The assessment of Ki-67 LI in 20 slides with Ki-67 LI of 5 to 25 % demonstrated a correlation similar to that in the specimens with an unrestricted range of Ki-67 LI in the study 1 {ICC, 0.68 (0.50-0.81) for the study 2, 0.66 (0.52-0.78) for the study 1}. Study 3) The assessment of Ki-67 LI in the same photographs yielded a considerably significant concordance among six pathologists {ICC, 0.94 (0.88-0.97)}. Conclusion: The counting system turned out better than the scoring system in terms of the inter-observer agreement of the Ki-67 LI assessment. The degree of concordance was by no means influenced by the range of Ki-67 LI. The concordance of the Ki-67 LI assessment among six participating pathologists was significantly high when the assessed field was fixed using the same photographs for evaluation, suggesting that the selection of the fields for evaluation is critical. These results suggest that identification of hot spots for evaluation is pivotal for obtaining the accurate Ki-67 LI of breast cancer and still images of these hot spots could provide reproducible results. [ABSTRACT FROM AUTHOR]