Predictive value of breast magnetic resonance imaging in detecting mammographically occult contralateral breast cancer: Can we target women more likely to have contralateral breast cancer?

BACKGROUND AND OBJECTIVES: Preoperative breast magnetic resonance imaging (B-MRI) staging in newly diagnosed breast cancer increases detection of synchronous contralateral findings, but may result in false-positive outcomes. This study objective was to identify women more likely of having mammographically occult, MRI detected contralateral breast cancer (CBC). METHODS: We performed a retrospective review of patients who had preoperative B-MRI prior to surgery from 2010 to 2015 and collected patient imaging and clinicopathologic data. Multivariate logistic regression was used to identify predictors of CBC. RESULTS: MRI resulted in contralateral findings in 201 of 1894 patients (10.6%). Overall 3.2% (60 of 1894) had synchronous CBC detected on B-MRI. The majority of CBCs (n = 60) were stage 0 or IA (85.0%), hormone receptor positive (94.9%), human epidermal growth factor receptor 2 (HER2/neu) negative (89.7%), and low/intermediate pathological grade (87.2%). Women more likely to have CBC were older (P < .001), had lobular index cancer (P = .03), and estrogen receptor (ER)+ (P = .027) or progesterone receptor (PR)+ (P = .002) tumors. On multivariate analysis (receiver operating characteristic curve area = 0.75), PR + status (P = .022), and older age (P = .004) were predictive of CBC. CONCLUSIONS: Preoperative MRI is most effective in detecting early stage, hormone receptor-positive CBC in older women.

Clinicopathologic analysis of a large series of microinvasive breast cancers.

Clinical management of microinvasive breast cancer (Tmic) remains controversial. Although metastases are infrequent in Tmic carcinoma patients, surgical treatment typically includes lymph node sampling. The objective of this study was to determine the rate and predictors of lymph node metastases, recurrence, and survival in a large series of Tmic breast carcinomas. Consecutive cases of Tmic were identified within our health care system from 2001 to 2015. We reviewed results of lymph node sampling and other pathologic factors including hormone receptor/HER2 status, associated in situ tumor size/grade, margin status, number of invasive foci, surgical/adjuvant therapies, and recurrence/survival outcomes. In this cohort, 294 Tmic cases were identified with mean follow-up of 4.6 years. Of 260 patients who underwent axillary staging, lymph node metastases were identified in 1.5% (all of which were ductal type). All Tmic cases with positive lymph node metastases had associated DCIS with size > 5 cm (5.3-8.5 cm) compared to a median DCIS tumor size of 2.5 cm (0.2-19.0 cm) for the entire cohort. No lymph node metastases were seen with microinvasive lobular carcinoma. During the follow-up period, there were no regional/distant recurrences or breast cancer-associated deaths in a mean follow-up period of 4.6 years. Two patients developed subsequent ipsilateral breast cancer (DCIS) in a different quadrant than the original Tmic. Clinical behavior of microinvasive breast cancer in this series is similar to DCIS. Lymph node metastases are uncommon and were only seen with ductal type microinvasive carcinoma. Our data suggest limited benefit for routine node sampling and support management of Tmic similar to DCIS, particularly for patients with DCIS < 5 cm in size.

HER2 Testing Characteristics Can Predict Residual Cancer Burden following Neoadjuvant Chemotherapy in HER2-Positive Breast Cancer.

OBJECTIVES: The response to HER2-targeted neoadjuvant chemotherapy (NAC) in HER2-positive (+) breast cancer can be quantified using residual cancer burden (RCB) pathologic evaluation to predict relapse free/overall survival. However, more information is needed to characterize the relationship between patterns of HER2 testing results and response to NAC. We evaluated clinicopathologic characteristics associated with RCB categories in HER2+ patients who underwent HER2-directed NAC. METHODS: A retrospective chart review was conducted with Stage I-III HER2+ breast cancer cases following NAC and surgical resection. HER2 immunohistochemistry (IHC) staining and fluorescence in situ hybridization (FISH), histologic/clinical characteristics, hormone receptor status, and RCB scores (RCB-0, RCB-I, RCB-II, and RCB-III) were evaluated. RESULTS: 64/151 (42.4%) patients with HER2+ disease had pathologic complete response (pCR). Tumors with suboptimal response (RCB-II and RCB-III) were more likely to demonstrate less than 100% HER2 IHC 3+ staining (p < 0.0001), lower HER2 FISH copies (p < 0.0001), and lower HER2/CEP17 ratios (p = 0.0015) compared to RCB-I and RCB-II responses. Estrogen receptor classification using ≥10% versus ≥1% staining showed greater association with higher RCB categories. CONCLUSIONS: HER2+ characteristics show differing response to therapy despite all being categorized as positive; tumors with less than 100% IHC 3+ staining, lower HER2 FISH copies, and lower HER2/CEP17 ratios resulted in higher RCB scores.

HER2 Testing: Insights From Pathologists' Perspective on Technically Challenging HER2 FISH Cases.

OBJECTIVE: College of American Pathologists and the American Society of Clinical Oncology guidelines provide straightforward criteria for HER2 interpretation in breast carcinomas; however, a subset of cases present unusual diagnostic dilemmas. MATERIALS AND METHODS: Ten challenging HER2 fluorescence in situ hybridization (FISH) cases were selected for analysis. The study included a variety of problematic cases such as those with discordant immunohistochemistry (IHC) and FISH results, cases with high intratumoral variability in HER2 copy number, a case with a highly amplified clone in 5% to 10% of the tumor sample, and a case with tumor cells containing tightly clumped HER2 signals. Six high volume HER2 FISH laboratories performed and interpreted HER2 FISH (adding HER2 IHC if necessary). Interpretation strategies were discussed. RESULTS: There was 100% concordance between laboratories in 4/10 cases. Tumors with increased intratumoral variability (tumors with high variability in HER2 copy number per cell but which otherwise do not fulfill College of American Pathologists and the American Society of Clinical Oncology criteria for heterogeneity) exhibited 100% concordance in 3/4 cases, but 1 case had only 50% agreement. Low positive HER2 cases (group 1 cases with <6 average HER2 copies/cell) had 1 laboratory disagreeing with the majority in 4/4 cases, and this was the only category with discordance between IHC and FISH methodologies. All laboratories identified the case with heterogeneity and interpreted it as positive. Five of the 6 laboratories interpreted the case with tightly clustered HER2 signals as positive. CONCLUSIONS: This study offers specific observations and interpretation strategies that laboratories can use when confronted with difficult HER 2 cases. It then highlights communication strategies a laboratory may use to discuss these unusual HER2 results with the clinical team.

Effects of Germline Pathogenic Variants, Cancer Subtypes, Tumor-related Characteristics, and Pregnancy-associated Diagnosis on Outcomes.

BACKGROUND: Although breast cancer (BC) is uncommon in women age ≤ 35 years, women in this age group may have more aggressive cancer subtypes and high-risk pathogenic variants (HRPVs). Higher recurrence and mortality rates in young patients may be related to differences in tumor biology, pathologic mutation status, or treatment. The purpose of this study was to evaluate germline mutation status and other factors that affect recurrence-free survival (RFS) and overall survival (OS) in young women with BC. MATERIALS AND METHODS: This was a retrospective study of women diagnosed with BC at age ≤ 35 years at Allina Health System from 2000 through 2017 (n = 306). Information was collected on germline mutation status, tumor characteristics (grade, hormone receptor, and human epidermal growth factor receptor 2), molecular subtype, pregnancy-associated cancers, and treatment. Survival analyses using Kaplan-Meier curves were conducted for RFS and OS. RESULTS: With mean follow-up of 6.5 years, OS was 87.0% for invasive cancers, RFS was 84.7%; 69% obtained genetic testing, and 26.9% had HRPVs. There were no differences in RFS or OS between patients with HRPV versus unknown/low/moderate risk variants. Recurrence analysis showed increased recurrence rates in luminal B-like cancers followed by triple negative and human epidermal growth factor receptor 2-positive cancers (P = .041). Pregnancy-associated BC diagnoses, angiolymphatic invasion, and tumor stage were associated with reduced OS. In spite of young age at diagnosis, nearly one-third of patients did not receive germline genetic testing. CONCLUSIONS: Similar survival patterns were found between women with HRPV versus no known mutations. Luminal B-like subtype, pregnancy-associated BC, angiolymphatic invasion, and cancer stage were associated with reduced OS.

Surgical Outcomes of Lobular Neoplasia Diagnosed in Core Biopsy: Prospective Study of 316 Cases.

BACKGROUND: Management recommendations for lobular neoplasia (LN) including lobular carcinoma-in-situ (LCIS) and atypical lobular hyperplasia (ALH) diagnosed in core biopsies (CB) are controversial. Our aim was to prospectively identify a subset of patients who do not require subsequent surgical excision (SE). PATIENTS AND METHODS: All patients diagnosed with LN on CB were enrolled and referred for SE. Cases with coexistent ductal carcinoma-in-situ or invasive carcinoma were excluded. Cases with coexistent ductal atypia (LN-DA) and LCIS variants (LN-V) were separated from pure classic LN (LN-C). Dedicated breast pathologists and radiologists reviewed cases with careful imaging/pathology correlation. RESULTS: Of 13,772 total percutaneous breast CB procedures, 302 of 370 patients diagnosed with LN underwent SE. Upgrade to carcinoma was present in 3.5% (8/228) LN-C, 26.7% LN-V (4/15), and 28.3% LN-DA (15/53). Calcifications were the imaging target for 180 (79%) of 228 LN-C cases; 7 were associated with upgrade (3.9%). Upgrades were rare for mass lesions (1/32) and magnetic resonance imaging-targeted lesions (0/14). Upgrades were similar for ALH and LCIS (3.4% vs. 4.5%). During postsurgical follow-up (mean, 34.5 months), 6.5% LN-C patients developed carcinoma in either breast. CONCLUSION: Although LN with nonclassic morphology or with associated ductal atypia requires SE, this can be avoided in LN-C diagnosed on CB targeting calcifications when careful imaging/pathology correlation is applied. Until larger numbers are studied, excising LN-C diagnosed as masses or magnetic resonance imaging-detected lesions may be prudent. Regardless of their selection for surgical management, LN patients need close surveillance in view of their long-term risk of breast cancer.