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.
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.
To compare the clinical features, natural history, and outcomes for women with "triple-negative" breast cancer with women with other types of breast cancer.
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.
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.
Triple-negative breast cancers have a more aggressive clinical course than other forms of breast cancer, but the adverse effect is transient.
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.
To develop a guideline to improve the accuracy of human epidermal growth factor receptor 2 (HER2) testing in invasive breast cancer and its utility as a predictive marker.
The American Society of ...Clinical Oncology and the College of American Pathologists convened an expert panel, which conducted a systematic review of the literature and developed recommendations for optimal HER2 testing performance. The guideline was reviewed by selected experts and approved by the board of directors for both organizations.
Approximately 20% of current HER2 testing may be inaccurate. When carefully validated testing is performed, available data do not clearly demonstrate the superiority of either immunohistochemistry (IHC) or in situ hybridization (ISH) as a predictor of benefit from anti-HER2 therapy.
The panel recommends that HER2 status should be determined for all invasive breast cancer. A testing algorithm that relies on accurate, reproducible assay performance, including newly available types of brightfield ISH, is proposed. Elements to reliably reduce assay variation (for example, specimen handling, assay exclusion, and reporting criteria) are specified. An algorithm defining positive, equivocal, and negative values for both HER2 protein expression and gene amplification is recommended: a positive HER2 result is IHC staining of 3+ (uniform, intense membrane staining of > 30% of invasive tumor cells), a fluorescent in situ hybridization (FISH) result of more than six HER2 gene copies per nucleus or a FISH ratio (HER2 gene signals to chromosome 17 signals) of more than 2.2; a negative result is an IHC staining of 0 or 1+, a FISH result of less than 4.0 HER2 gene copies per nucleus, or FISH ratio of less than 1.8. Equivocal results require additional action for final determination. It is recommended that to perform HER2 testing, laboratories show 95% concordance with another validated test for positive and negative assay values. The panel strongly recommends validation of laboratory assay or modifications, use of standardized operating procedures, and compliance with new testing criteria to be monitored with the use of stringent laboratory accreditation standards, proficiency testing, and competency assessment. The panel recommends that HER2 testing be done in a CAP-accredited laboratory or in a laboratory that meets the accreditation and proficiency testing requirements set out by this document.
To develop a guideline to improve the accuracy of human epidermal growth factor receptor 2(HER2) testing in invasive breast cancer and its utility as a predictive marker.
The American Society of ...Clinical Oncology and the College of American Pathologists convened an expert panel, which conducted a systematic review of the literature and developed recommendations for optimal HER2 testing performance. The guideline was reviewed by selected experts and approved by the board of directors for both organizations.
Approximately 20% of current HER2 testing may be inaccurate. When carefully validated testing is performed, available data do not clearly demonstrate the superiority of either immunohistochemistry(IHC) or in situ hybridization (ISH) as a predictor of benefit from anti-HER2 therapy.
The panel recommends that HER2 status should be determined for all invasive breast cancer. A testing algorithm that relies on accurate, reproducible assay performance, including newly available types of brightfield ISH, is proposed. Elements to reliably reduce assay variation (for example, specimen handling, assay exclusion, and reporting criteria) are specified. An algorithm defining positive, equivocal, and negative values for both HER2 protein expression and gene amplification is recommended: a positive HER2 result is IHC staining of 3 + (uniform, intense membrane staining of 30% of invasive tumor cells), a fluorescent in situ hybridization (FISH) result of more than six HER2 gene copies per nucleus or a FISH ratio (HER2 gene signals to chromosome 17 signals) of more than 2.2; a negative result is an IHC staining of 0 or 1 +, a FISH result of less than 4.0 HER2 gene copies per nucleus, or FISH ratio of less than 1.8. Equivocal results require additional action for final determination. It is recommended that to perform HER2 testing, laboratories show 95% concordance with another validated test for positive and negative assay values. The panel strongly recommends validation of laboratory assay or modifications, use of standardized operating procedures, and compliance with new testing criteria to be monitored with the use of stringent laboratory accreditation standards, proficiency testing, and competency assessment. The panel recommends that HER2 testing be done in a CAP-accredited laboratory or in a laboratory that meets the accreditation and proficiency testing requirements set out by this document.
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.
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.
Assessment of human epidermal growth factor receptor-2 status is standard practice in women with breast cancer. Most laboratories use immunohistochemistry as a screening test, with equivocal results ...confirmed by fluorescence in-situ hybridization (FISH). Chromogenic in-situ hybridization (CISH) is a relatively new method for detection of gene amplification using a peroxidase reaction, which can be viewed using a standard light microscope. This study was undertaken to validate CISH as a method for assessing human epidermal growth factor receptor-2 gene amplification. The gene amplification status of human epidermal growth factor receptor-2 immunohistochemistry negative (0/1+, n=69; Group 1), immunohistochemistry positive (3+, n=50; Group 2) and equivocal tumor samples (2+, n=135; Group 3) was evaluated by FISH and CISH, and the concordance between FISH and CISH results calculated. In Group 1, 67/69 cases did not show amplification by CISH and 69/69 showed no amplification by FISH. Two cases were discordant; therefore, fluorescence/CISH concordance was 97%. In Group 2, 46/50 cases were amplified by FISH and 47/50 cases were amplified by CISH; three cases were not amplified by either method (immunohistochemistry false-positives). Only one case showed discordant FISH and CISH results, making the fluorescence/CISH concordance 98%. In Group 3, 89/135 cases were not amplified and 37/135 were amplified by both methods. Nine cases were discordant, giving a fluorescence/CISH concordance of 93%. The discordant cases were those with very low or borderline amplification with FISH. The high level of concordance between FISH and CISH seen in this study suggests that CISH may be a viable alternative to FISH for use in the human epidermal growth factor receptor-2 testing algorithm.
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.
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