Pilot Study on the Utility of Circulating HER2/Neu Levels in the Serum of Breast Cancer Patients.

BACKGROUND/AIM: Accurate and timely assessment of the human epidermal growth factor receptor 2 (HER2/neu) overexpression is pivotal for the identification of breast cancer (BC) patients that could benefit from HER2-targeted therapy. Currently approved tissue-based HER2 assays (tHER2) are limited to testing HER2 status on tumor samples obtained at a few points in time during the course of the disease. Herein, we assessed serum HER2 (sHER2) status longitudinally in 81 serial samples prospectively collected from 43 consenting patients pre- and post-therapy to revisit the idea of serum testing in the follow-up of BC patients. PATIENTS AND METHODS: The cohort included 11 patients with early BC (EBC), 17 with locally advanced BC (LABC), and 15 with metastatic BC (MBC). sHER2 concentrations were measured using a quantitative ELISA-based technique, using 15 ng/ml as the cut-off for positivity. RESULTS: At baseline, sHER2 was negative in all EBC patients while positive in 1 LABC and 5 MBC patients. Sixteen BC patients (10 LABC, 1 EBC, and 5 MBC) were tHER2 positive. sHER2 and tHER2 results were discordant in 14 patients. Among the 16 tHER2 positive patients, 9 LABC, 1 EBC and 2 MBC patients were sHER2 negative. Conversely, 2 MBC patients were sHER2 positive, despite being tHER2 negative. A rise or drop of sHER2 by >20% correlated with disease progression or pathological response to therapy, respectively. CONCLUSION: The study demonstrated the technical validity and feasibility of the sHER2 assay. Findings suggest that post initial tissue diagnosis (tHER2), sHER2 assay may supplement subsequent tissue tests to monitor disease status and response to therapy. Further studies to assess the role of HER2 targeted therapies in sHER-positive/tHER2-negative cases upon disease progression are warranted.

Intraoperative Assessment of Sentinel Lymph Nodes in Breast Cancer Patients Post-Neoadjuvant Therapy.

BACKGROUND: Shift toward minimizing axillary lymph node dissection in patients with breast cancer post neoadjuvant therapy has led to the assessment of sentinel lymph nodes by frozen section intraoperatively to determine the need for axillary lymph node dissection. However, few studies have examined the accuracy of sentinel lymph node frozen section after neoadjuvant therapy. Our objective is to compare the accuracy of sentinel lymph node frozen section in patients with breast cancer with and without neoadjuvant therapy and to identify features that may influence accuracy. DESIGN: We identified 161 sentinel lymph node frozen section from 77 neoadjuvant therapy patients and 255 sentinel lymph node frozen section from 88 non-neoadjuvant therapy patients diagnosed between 2010 and 2016 in 2 institutions. The frozen section diagnoses were compared to the final diagnoses, and clinicopathologic data were analyzed. RESULTS: The sensitivity, specificity, and accuracy of frozen section analysis were comparable between neoadjuvant therapy patients and non-neoadjuvant therapy patients (71.9% vs 50%, 100% vs 100%, and 88.3% vs 81.8%). Nine (11.7%) of 77 neoadjuvant therapy patients had discordant results, most often due to undersampling (tumor absent on frozen section slide). Four of these patients subsequently underwent axillary lymph node dissection. Discordant results (all false negatives) were significantly more likely in neoadjuvant therapy patients with Estrogen Receptor-positive/HER2-negative status, and in sentinel lymph node with pN1mic and pN0i+ deposits; age, preneoadjuvant therapy lymph node status, histotype, nuclear grade, tumor size, and response to neoadjuvant therapy showed no significant differences. For non-neoadjuvant therapy cases, large tumor size, lobular histotype, and sentinel lymph node with pN1mic and pN0i+ were associated with false-negative frozen section assessment. CONCLUSION: Sentinel lymph node frozen section diagnosis post-neoadjuvant therapy has comparable sensitivity, specificity, and accuracy to the sentinel lymph node frozen section diagnosis in the non-neoadjuvant therapy setting.

Ductal carcinoma in situ of the breast: an update for the pathologist in the era of individualized risk assessment and tailored therapies.

Ductal carcinoma in situ (DCIS) is a neoplastic proliferation of mammary ductal epithelial cells confined to the ductal-lobular system, and a non-obligate precursor of invasive disease. While there has been a significant increase in the diagnosis of DCIS in recent years due to uptake of mammography screening, there has been little change in the rate of invasive recurrence, indicating that a large proportion of patients diagnosed with DCIS will never develop invasive disease. The main issue for clinicians is how to reliably predict the prognosis of DCIS in order to individualize patient treatment, especially as treatment ranges from surveillance only, breast-conserving surgery only, to breast-conserving surgery plus radiotherapy and/or hormonal therapy, and mastectomy with or without radiotherapy. We conducted a semi-structured literature review to address the above issues relating to "pure" DCIS. Here we discuss the pathology of DCIS, risk factors for recurrence, biomarkers and molecular signatures, and disease management. Potential mechanisms of progression from DCIS to invasive cancer and problems faced by clinicians and pathologists in diagnosing and treating this disease are also discussed. Despite the tremendous research efforts to identify accurate risk stratification predictors of invasive recurrence and response to radiotherapy and endocrine therapy, to date there is no simple, well-validated marker or group of variables for risk estimation, particularly in the setting of adjuvant treatment after breast-conserving surgery. Thus, the standard of care to date remains breast-conserving surgery plus radiotherapy, with or without hormonal therapy. Emerging tools, such as pathologic or biologic markers, may soon change such practice. Our review also includes recent advances towards innovative treatment strategies, including targeted therapies, immune modulators, and vaccines.

Comparative Analysis of Human Epidermal Growth Factor Receptor 2 Testing in Breast Cancer According to 2007 and 2013 American Society of Clinical Oncology/College of American Pathologists Guideline Recommendations.

Purpose To study the effect of the 2013 updates to the 2007 American Society of Clinical Oncology/College of American Pathologists recommendations for human epidermal growth factor receptor 2 (HER2) testing in breast cancer on testing patterns and interpretation in a large regional reference laboratory. Patients and Methods Patient cases with HER2 testing scores for breast biomarker evaluation were selected from our laboratory information system during two 12-month periods (2012 and 2014). The number of tests performed, type of specimens, proportion of HER2-positive and equivocal patient cases, and number of repeat tests on subsequent excisional specimens were examined and compared. Results Although the number of samples tested increased between 2012 and 2014 (2,201 v 2,558 patient cases; 2,278 v 2,659 tumors), HER2 positivity remained constant (15.7% v 15.5%, respectively). The number of repeat tests performed within 6 months more than doubled (122 [5.5%) of 2,201 v 302 [11.8%] of 2,558; P < .001), and the proportion of immunohistochemistry (IHC) 2+ tumors was significantly lower in 2014 than in 2012 (20.3% v 25.3%; P < .001). However, the proportion of patient cases with unresolved HER2 statuses (equivocal by IHC and in situ hybridization) was significantly higher in 2014 (four of 2,278 v 90 of 2,660; P < .001). Conclusion Our findings indicate that the 2013 updates to the American Society of Clinical Oncology/College of American Pathologists recommendations for HER2 testing in breast cancer did not affect the overall HER2-positivity rate or the proportion of patients eligible for HER2-targeted therapy. The proportion of tests and repeat tests performed increased, as did the number of patient cases categorized as ISH equivocal. The benefit of targeted therapy in the equivocal group is not proven, so targeted therapy should not be considered for patients in this category which should be redefined in future iterations of the recommendations.

Human epidermal growth factor receptor 2 testing in primary breast cancer in the era of standardized testing: a Canadian prospective study.

PURPOSE: Therapies that target overexpression of human epidermal growth factor receptor 2 (HER2) rely on accurate and timely assessment of all patients with new diagnoses. This study examines HER2 testing of primary breast cancer tissue when performed with immunohistochemistry (IHC) and additional in situ hybridization (ISH) for negative cases (IHC 0/1+). The analysis focuses on the rate of false-negative HER2 tests, defined as IHC 0/1+ with an ISH ratio ≥ 2.0, in eight pathology centers across Canada. PATIENTS AND METHODS: Whole sections of surgical resections or tissue microarrays (TMAs) from invasive breast carcinoma tissue were tested by both IHC and ISH using standardized local methods. Samples were scored by the local breast pathologist, and consecutive HER2-negative IHC results (IHC 0/1+) were compared with the corresponding fluorescence or silver ISH result. RESULTS: Overall, 711 surgical excisions of primary breast cancer were analyzed by IHC and ISH; HER2 and chromosome 17 centromere (CEP17) counts were available in all cases. The overall rate of false-negative samples was 0.84% (six of 711 samples). Interpretable IHC and ISH scores were available in 1,212 cases from TMAs, and the overall rate of false-negative cases was 1.6% (16 of 978 cases). CONCLUSION: Our observation confirms that IHC is an adequate test to predict negative HER2 status in primary breast cancer in surgical excision specimens, even when different antibodies and IHC platforms are used. The study supports the American Society of Clinical Oncology/College of American Pathologists and Canadian testing algorithms of using IHC followed by ISH for equivocal cases.

HER2 in situ hybridization in breast cancer: clinical implications of polysomy 17 and genetic heterogeneity.

Trastuzumab-containing therapy is a standard of care for patients with HER2+ breast cancer. HER2 status is routinely assigned using in situ hybridization to assess HER2 gene amplification, but interpretation of in situ hybridization results may be challenging in tumors with chromosome 17 polysomy or intratumoral genetic heterogeneity. Apparent chromosome 17 polysomy, defined by increased chromosome enumeration probe 17 (CEP17) signal number, is a common genetic aberration in breast cancer and represents an alternative mechanism for increasing HER2 copy number. Some studies have linked elevated CEP17 count ('polysomy') with adverse clinicopathologic features and HER2 overexpression, although there are numerous discrepancies in the literature. There is evidence that elevated CEP17 ('polysomy') count might account for trastuzumab response in tumors with normal HER2:CEP17 ratios. Nonetheless, recent studies establish that apparent 'polysomy' (CEP17 increase) is usually related to focal pericentromeric gains rather than true polysomy. Assigning HER2 status may also be complex where multiple cell subclones with distinct HER2 amplification characteristics coexist within the same tumor. Such genetic heterogeneity affects up to 40% of breast cancers when assessed according to a College of American Pathologists guideline, although other definitions have been proposed. Recent data have associated heterogeneity with unfavorable clinicopathologic variables and poor prognosis. Genetically heterogeneous tumors harboring HER2-amplified subclones have the potential to benefit from trastuzumab, but this has yet to be evaluated in clinical studies. In this review, we discuss the implications of apparent polysomy 17 and genetic heterogeneity for assigning HER2 status in clinical practice. Among our recommendations, we support the use of mean HER2 copy number rather than HER2:CEP17 ratio to define HER2 positivity in cases where coamplification of the centromere might mask HER2 amplification. We also highlight a need to harmonize in situ hybridization scoring methodology to support accurate HER2 status determination, particularly where there is evidence of heterogeneity.

Experts' opinion: Recommendations for retesting breast cancer metastases for HER2 and hormone receptor status.

The human epidermal growth factor receptor 2 (HER2) and hormone receptor status of recurrent breast cancer may change between the tumor and metastases from negative to positive and vice versa, potentially affecting the treatment regimen. Retesting of metastases may therefore be crucial to allow appropriate selection of patients for whom targeted therapy is indicated; however, retesting is not routinely performed. This article recommends that metastases be retested for HER2 and hormone receptor status and provides practical guidance on when and how to retest, as agreed by a panel of expert pathologists with extensive experience of HER2 and hormone receptor testing.

Systematic review on hormone receptor testing in breast cancer.

Assessment of hormone receptors (estrogen and progesterone) helps to direct therapy for women with breast cancer. Immunohistochemistry is most commonly used to assess hormone receptor status and it is essential that these tests are performed accurately and reliably within and across laboratories. The overall purpose of this guideline is to improve the quality and accuracy of hormone receptor testing and its utility as a prognostic and predictive marker for invasive and in situ breast cancer. Medline, EMBASE, the Cochrane Database of Systematic Reviews, and abstracts from the San Antonio Breast Cancer Symposium were searched. An environmental scan of the internet and of international guideline developers and key organizations was performed. Preanalytic elements such as the collection, fixation, and storage of samples, and analytic elements such as selection of antibodies and scoring methods that seem to offer the best results for immunohistochemical assessment of hormone receptors are presented. Proficiency testing or quality assurance of immunohistochemistry is described.

Intraoperative consultation for axillary sentinel lymph node biopsy: an 8-year audit.

To summarize the authors' 8-year institutional experience with intraoperative consultation via frozen section (FS) on sentinel lymph node biopsy (SLNB) in breast cancer patients we recorded the, complete operative procedure including additional surgery on the ipsilateral axilla and intraoperative consultation and permanent histopathologic processing for all cases with inoperative consultation on SLNB in breast cancer patients between the groups, chi(2) and Fisher's exact tests were used. Intraoperative consultation was positive in 116/706 cases (16.4%) and final pathology in 158/706 cases (22.4%); the false-negative rate was 26.6%, the false-positive rate was 0%, and the overall accuracy was 94%. False-negative rate was significantly associated with the size of metastasis (micro vs macrometastasis; P < .002) but not significantly associated with the histologic type (P = 0.76) or pathologist expertise (P = 0.08). The rate of spared second procedures was 92% when calculated exclusively for patients who ultimately underwent ALND. Intraoperative consultation via FS for SLNB is a safe practice that can reliably save clinically node-negative patients a second surgery.

Time to disease recurrence in basal-type breast cancers: effects of tumor size and lymph node status.

BACKGROUND: : Basal-like breast cancers are a subgroup of breast cancers defined by the absence of staining for estrogen-receptor (ER), progesterone receptor (PR), and human epidermal growth factor receptor 2 (HER-2/neu) and by positive staining for the cytokeratins (CKs) expressed in the myoepithelial cells of the ducts and lobules (CK5/CK6, CK14) and for epidermal growth factor receptor (EGFR). This class of tumors has an unusually aggressive course, and it is not clear whether conventional prognostic factors for breast cancers also predict outcome for patients who have the basal phenotype. METHODS: : A panel of 962 breast cancers was stained for 5 markers (ER, PR, HER-2/neu, CK5/CK6, and EGFR). The patients were followed for clinical outcomes for up to 15 years from diagnosis, and the rates of distant disease recurrence and death were compared by tumor size (< or =2 cm or >2 cm) and by lymph node status within the subgroups of women with basal and nonbasal cancers. RESULTS: : Of the 962 women with breast cancer, 116 cancers were basal (12%), 845 were nonbasal (88%), and 1 could not be classified as either basal or nonbasal and was excluded. In total, 426 tumors measured < or =2 cm (45%), and 530 tumors measured >2 cm (55%). Among women with nonbasal cancers, large tumor size was an adverse prognostic factor. Among women with basal cancers, a transient adverse effect of size on disease recurrence was observed; however, after 10 years, mortality rates were equal for women with small tumors and women with large tumors. CONCLUSIONS: : Among women with basal breast cancers, the long-term prognosis was similar for women with large tumors and women with small tumors. However, women with large basal tumors appeared to develop recurrent disease sooner. Cancer 2009. (c) 2009 American Cancer Society.

Value and limitations of measuring HER-2 extracellular domain in the serum of breast cancer patients.

The human epidermal receptor-2 (HER-2) is overexpressed or amplified in 15% to 25% of breast cancers. Determination of HER-2 tumor status offers clinically useful information, as it selects patients who may benefit from treatment with trastuzumab, the monoclonal antibody against HER-2. Currently approved methods for HER-2 testing include immunohistochemistry or fluorescent in situ hybridization using tumor tissue. A fragment of HER-2 composed of its extracellular domain (ECD) can also be detected in the serum of some patients with breast cancer. As an easily accessible tumor marker, it could offer additional useful prognostic or predictive information. This review will briefly address the biology of the circulating HER-2 ECD and discuss the evidence to support the role, if any, for measuring HER-2 ECD levels in women with breast cancer. In particular, we focus on the value and limitations of serum ECD in both early and advanced breast cancer in the following clinical contexts: as a marker of HER-2 tumor tissue status; clinical implications of raised levels in women who have a tumor not overexpressing HER-2; as a prognostic indicator and as a predictor of response to treatment; and as a monitoring tool for early recurrence. On the basis of our review of the literature, we conclude that there is currently insufficient evidence to support the use of serum HER-2 ECD in the routine management of individual patients with breast cancer. This conclusion is in agreement with the 2007 American Society of Clinical Oncology guidelines on the use of biomarkers in breast cancer.

Patterns of recurrence in the basal and non-basal subtypes of triple-negative breast cancers.

Traditional prognostic markers for breast cancer include estrogen receptor (ER), progesterone receptor (ER) and HER2/neu. Negative staining for these three markers defines the 'triple-negative' phenotype. By adding markers for cytokeratin 5/6 and EGFR, triple-negative breast cancers can be divided into 'basal-like' and 'normal-like' subgroups. We conducted immuno-staining on a panel of 958 patients with breast cancer, using all five markers and we followed the patients for distal recurrence and death. We compared rates of distal recurrence in the basal-like and normal-like subgroups with that of women with ER-positive breast cancer. Only 16 of 958 women had normal-like breast cancers. These cancers resembled basal-like cancers in that they had a high proliferative index, but the women with normal-like breast cancers resembled ER-positive women in terms of distant recurrence. The addition of CK5/6 and EGFR to the standard panel (ER/PR/HER2/neu) defines a small subgroup of women with normal-like breast cancer. The prognosis of these women may be superior to that of basal-like breast cancers but firm conclusions cannot be made.

Pattern of metastatic spread in triple-negative breast cancer.

PURPOSE: The prognosis of women with triple-negative breast cancers (defined as cancers that are estrogen receptor-negative, progesterone receptor-negative and HER2/neu negative) is poor, compared to women with other subtypes of breast cancer. It is proposed that the underlying difference in recurrence rates may be explained in part by different routes of metastatic spread. EXPERIMENTAL DESIGN: We studied a cohort of 1608 patients diagnosed with breast cancer, diagnosed between January 1987 and December 1997 at Women's College Hospital in Toronto. Triple-negative breast cancers were defined as those that were estrogen receptor-negative, progesterone receptor-negative and HER2/neu-negative. We compared the incidence rates of metastatic spread to bone and to other (non-bone) organs in women with triple-negative and other forms of breast cancer. RESULTS: Of the 1,608 patients, 180 (11.2%) had triple-negative breast cancer. The 1608 women were followed for a median of 9.0 years (range 0.1-19 years). Compared to other patients, those with triple-negative breast cancer had an increased likelihood of distant recurrence over the study period (adjusted hazard ratio (HR) 1.9; 95% CI: 1.5-2.5, P < 0.0001). The relatively poor prognosis was apparent in the five years after diagnosis (HR 2.9; 95% CI: 2.1-3.9; P = 0.0001) but not thereafter (HR 0.5; 95% CI: 0.2-1.1; P = 0.07). In particular, women with triple-negative breast cancer were four times more likely to experience a visceral metastasis within five years of diagnosis than those with other types of cancer (HR 4.0; 95% CI: 2.7-5.9; P < 0.0001). The rates of bone metastases were comparable for triple-negative and for other forms of cancer in this time period (HR 0.8; 95% CI: 0.4-1.6 P = 0.5). CONCLUSIONS: The excess risk of distant recurrence in triple-negative breast cancers, versus other forms of cancer, is attributable in large part to an excess of visceral metastases in the first five years following diagnosis.

Immunophenotyping of serous carcinoma of the female genital tract.

To update the data on the expression of 'mesothelioma markers' by serous carcinomas of various sites we have studied cases from ovary (n=56), endometrium (n=37), fallopian tube (n=6), primary peritoneum (n=5) and cervix (n=3) using a panel of antibodies (WT1, P53, estrogen receptors, HER2/neu, D2-40, cytokeratin 5/6 and E-cadherin). Ovarian carcinomas demonstrated D2-40 and cytokeratin 5/6 immunoreactivity in 23.2 and 55.4% of cases, respectively. Endometrial carcinomas demonstrated D2-40 and cytokeratin 5/6 immunoreactivity in 43.2 and 37.8% of cases, respectively. D2-40 staining pattern was predominantly focal; however, strong reactivity was identified in 16.2% of endometrial and 10.7% of ovarian carcinomas. HER2/neu oncoprotein overexpression was demonstrated in 7 of 37 (18.9%) uterine serous carcinomas. In contrast, all the serous carcinomas of the other sites were HER2/neu negative. The proportion of positive cases was significantly different in ovarian vs endometrial carcinomas regarding WT1 (P=0.0458), estrogen receptors (P<0.001) reactivity and HER2/neu overexpression (P=0.0025). D2-40 and cytokeratin 5/6 are expressed in a considerable proportion of serous carcinomas and should be used cautiously in a 'mesothelioma panel' in situations where serous carcinoma is in the differential diagnosis. HER2/neu was exclusively overexpressed in serous carcinomas of endometrial origin.

Expression of c-kit in fibroepithelial lesions of the breast is a mast cell phenomenon.

The expression of c-kit, a protooncogene tyrosine kinase receptor (CD117), in phyllodes tumors of the breast has been the subject of recent investigations. We examined stromal c-kit expression by immunohistochemistry in 68 cases comprising fibroadenomas, fibroadenomas with cellular stroma, and benign, borderline, and malignant phyllodes tumors. Membrane staining was identified in the epithelium of 82% of cases, representing all diagnostic categories in the study. Membrane and cytoplasmic staining was detected in scant cells in the stroma in 74% of the cases in the study, again, across all diagnostic entities. However, when toluidine blue and tryptase staining was performed, the staining pattern matched that of c-kit in the number of cells and their distribution, thereby confirming the presence of mast cells and excluding any appreciable level of true stromal c-kit staining. One borderline and one malignant phyllodes tumor showed a diffuse weak stromal signal, which could not be accounted for by toluidine blue and tryptase. These cases were further tested for the presence of known activating mutations of c-kit and PDGFR-alpha, and yielded negative results. Our findings indicate that c-kit is an unlikely player in the pathogenesis of fibroepithelial lesions of the breast. The positive stromal staining suggested previously by other authors may be attributed to mast cells. C-kit, therefore, has neither a diagnostic nor a prognostic role in phyllodes tumors, and there is no rationale for the treatment of recurrent of malignant phyllodes tumor patients with tyrosine kinase inhibitors.

Estrogen and progesterone receptor levels in nonneoplastic breast epithelium of breast cancer cases versus benign breast biopsy controls.

BACKGROUND: Previous studies and biological mechanisms of carcinogenesis suggest that the steroid receptor content of benign breast epithelium may be related to breast cancer risk. The objective in this study was to compare the levels of estrogen receptor-alpha (ER) and progesterone receptor (PR) in nonneoplastic breast epithelium between breast cancer cases and biopsy controls. METHODS: Between 1995 and 1997 at two sites (Women's College Hospital in Toronto and Kingston General Hospital), 667 women who were scheduled for diagnostic excisional breast biopsies completed a questionnaire providing personal information and agreed to allow analysis of routinely resected tissue. Histological slides with nonneoplastic epithelium were available for 101 cancer cases and 200 biopsy controls in Toronto and for 105 cancer cases and 119 controls in Kingston. Nonneoplastic epithelium was examined with immunohistochemical assays to determine the percent of epithelial cells staining for ER and PR. Unconditional logistic regression was used to calculate odds ratios (OR) stratified by study site. RESULTS: The ER content of nonneoplastic tissue was higher in cases than biopsy controls in unadjusted analyses; after adjustment for age, however, a weak association remained in only one of the study sites. After adjustment for age, the PR content of nonneoplastic tissue was slightly lower in breast cancer cases than controls in one study site. Furthermore, this inverse association was confined to women with PR negative breast cancer in comparison to the controls. No interaction between ER and PR content of nonneoplastic tissue was observed in relation to the odds of having breast cancer. CONCLUSION: The results of this study are consistent with only a slight indication of increased ER levels in nonneoplastic tissue in breast cancer cases relative to controls. This study contributes to the understanding of breast cancer by examining both ER and PR in nonneoplastic tissue. Limitations remain, however, such as the necessity of using as controls women with benign breast changes, difficulties in selecting the appropriate tissue for analysis, and tissue sampling concurrent to diagnosis.

Triple-negative breast cancer: clinical features and patterns of recurrence.

PURPOSE: To compare the clinical features, natural history, and outcomes for women with "triple-negative" breast cancer with women with other types of breast cancer. EXPERIMENTAL DESIGN: We studied a cohort of 1,601 patients with breast cancer, diagnosed between January 1987 and December 1997 at Women's College Hospital in Toronto. Triple-negative breast cancers were defined as those that were estrogen receptor negative, progesterone receptor negative, and HER2neu negative. The prognostic significance of triple-negative breast cancer was explored. RESULTS: The median follow-up time of the 1,601 women was 8.1 years. One hundred and eighty of 1,601 patients (11.2%) had triple-negative breast cancer. Compared with other women with breast cancer, those with triple-negative breast cancer had an increased likelihood of distant recurrence (hazard ratio, 2.6; 95% confidence interval, 2.0-3.5; P < 0.0001) and death (hazard ratio, 3.2; 95% confidence interval, 2.3-4.5; P < 0.001) within 5 years of diagnosis but not thereafter. The pattern of recurrence was also qualitatively different; among the triple-negative group, the risk of distant recurrence peaked at approximately 3 years and declined rapidly thereafter. Among the "other" group, the recurrence risk seemed to be constant over the period of follow-up. CONCLUSIONS: Triple-negative breast cancers have a more aggressive clinical course than other forms of breast cancer, but the adverse effect is transient.

Standardization of HER2 testing: results of an international proficiency-testing ring study.

Human epidermal growth factor receptor 2 (HER2) positivity in breast cancer is a prognostic factor regarding tumor aggressiveness and a predictive factor for response to trastuzumab (Herceptin). Early and accurate HER2 testing of all breast cancer patients at primary diagnosis is essential for optimal disease management. Routine HER2 tests, such as immunohistochemistry and fluorescence in situ hybridization (FISH), are subject to interlaboratory variation, and validation by laboratory proficiency testing is important to improve standardization. This study compared immunohistochemistry and FISH testing between five international pathology reference centers. Each center evaluated 20 immunohistochemistry and 20 FISH breast cancer specimens in five testing rounds. In each round, one center selected two sets of four different invasive tumor specimens (set A for immunohistochemistry and set B for FISH) and sent samples to the other four centers in a blinded manner, while retaining samples for its own evaluation. Results were analyzed by an independent coordinator. With immunohistochemistry, there were no differences between the five centers for any of the specimens at the level of diagnostic decision (positive or negative HER2 status). However, differences between laboratories were observed in immunohistochemistry scoring. Of the 20 specimens, four were scored as negative (0/1+) and five as positive (3+) in all centers; eight were negative or equivocal (2+), and three positive or equivocal. After FISH retesting of nine of the 11 equivocal immunohistochemistry cases, consensus was achieved in 15 of 18 (83%) specimens. FISH analysis of set B specimens resulted in consensus between centers in 16 of 20 (80%) specimens (six negative and 10 positive). All four discordant FISH specimens were scored as having HER2:CEP17 ratios within the range 1.7-2.3 by at least one center. Equivocal immunohistochemistry and borderline FISH cases are difficult to interpret, even for highly experienced and validated laboratories, highlighting the need for quality-control procedures.