Immediate and delayed risk of breast cancer associated with classic lobular carcinoma in situ and its variants.

OBJECTIVE: To determine the risk of breast cancer due to lobular carcinoma in situ (LCIS). METHODS: This retrospective IRB-approved study identified cases of LCIS after percutaneous breast biopsy from 7/2005 to 7/2022. Excluded were cases with less than 2 years of imaging surveillance or a concurrent ipsilateral breast cancer diagnosis within 6 months of the LCIS diagnosis. Final outcomes of cancer versus no cancer were determined by pathology at surgical excision or the absence of cancer on imaging surveillance. RESULTS: A total of 116 LCIS lesions were identified. The primary imaging findings targeted for percutaneous biopsy included calcifications (50.0%, 58/116), MR enhancing lesions (25.0%, 29/116), noncalcified mammographic architectural distortions (10.3%, 12/116), or masses (14.7%, 17/116). Surgical excision was performed in 49.1% (57/116) and imaging surveillance was performed in 50.9% (59/116) of LCIS cases. There were 22 cancers of which 11 cancers were discovered at immediate excision [19.3% (11/57) immediate upgrade] and 11 cancers developed later while on imaging surveillance [18.6% (11/59) delayed risk for cancer]. Among all 22 cancers, 63.6% (14/22) occurred at the site of LCIS (11 at immediate excision and 3 at surveillance) and 36.4% (8/22) occurred at a location away from the site of LCIS (6 in a different quadrant and 2 in the contralateral breast). CONCLUSION: LCIS has both an immediate risk (19.3%) and a delayed risk (18.6%) for cancer with 90.9% occurring in the ipsilateral breast (63.6% at and 27.3% away from the site of LCIS) and 9.1% occurring in the contralateral breast.

European quality indicators developed by the European Commission Initiative on Breast Cancer: a first nationwide assessment for the Dutch setting.

PURPOSE: This observational study aims to assess the feasibility of calculating indicators developed by the European Commission Initiative on Breast Cancer (ECIBC) for the Dutch breast cancer population. METHODS: Patients diagnosed with invasive or in situ breast cancer between 2012 and 2018 were selected from the Netherlands Cancer Registry (NCR). Outcomes of the quality indicators (QI) were presented as mean scores and were compared to a stated norm. Variation between hospitals was assessed by standard deviations and funnel plots and trends over time were evaluated. The quality indicator calculator (QIC) was validated by comparing these outcomes with the outcomes of constructed algorithms in Stata. RESULTS: In total, 133,527 patients were included. Data for 24 out of 26 QIs were available in the NCR. For 67% and 67% of the QIs, a mean score above the norm and low or medium hospital variation was observed, respectively. The proportion of patients undergoing a breast reconstruction or neoadjuvant systemic therapy increased over time. The proportion treated within 4 weeks from diagnosis, having >10 lymph nodes removed or estrogen negative breast cancer who underwent adjuvant chemotherapy decreased. The outcomes of the constructed algorithms in this study and the QIC showed 100% similarity. CONCLUSION: Data from the NCR could be used for the calculation of more than 92% of the ECIBC indicators. The quality of breast cancer care in the Netherlands is high, as more than half of the QIs already score above the norm and medium hospital variation was observed. The QIC can be easy and reliably applied.

Upgrade Rates of Variant Lobular Carcinoma In Situ Compared to Classic Lobular Carcinoma In Situ Diagnosed in Core Needle Biopsies: A 10-Year Single Institution Retrospective Study.

The primary aim of this study was to determine the upgrade rates of variant lobular carcinoma in situ (V-LCIS, ie, combined florid [F-LCIS] and pleomorphic [P-LCIS]) compared with classic LCIS (C-LCIS) when diagnosed on core needle biopsy (CNB). The secondary goal was to determine the rate of progression/development of invasive carcinoma on long-term follow-up after primary excision. After institutional review board approval, our institutional pathology database was searched for patients with "pure" LCIS diagnosed on CNB who underwent subsequent excision. Radiologic findings were reviewed, radiologic-pathologic (rad-path) correlation was performed, and follow-up patient outcome data were obtained. One hundred twenty cases of LCIS were identified on CNB (C-LCIS = 97, F-LCIS = 18, and P-LCIS = 5). Overall upgrade rates after excision for C-LCIS, F-LCIS, and P-LCIS were 14% (14/97), 44% (8/18), and 40% (2/5), respectively. Of the total cases, 79 (66%) were deemed rad-path concordant. Of these, the upgrade rate after excision for C-LCIS, F-LCIS, and P-LCIS was 7.5% (5 of 66), 40% (4 of 10), and 0% (0 of 3), respectively. The overall upgrade rate for V-LCIS was higher than for C-LCIS (P = .004), even for the cases deemed rad-path concordant (P value: .036). Most upgraded cases (23 of 24) showed pT1a disease or lower. With an average follow-up of 83 months, invasive carcinoma in the ipsilateral breast was identified in 8/120 (7%) cases. Six patients had died: 2 of (contralateral) breast cancer and 4 of other causes. Because of a high upgrade rate, V-LCIS diagnosed on CNB should always be excised. The upgrade rate for C-LCIS (even when rad-path concordant) is higher than reported in many other studies. Rad-path concordance read, surgical consultation, and individualized decision making are recommended for C-LCIS cases. The risk of developing invasive carcinoma after LCIS diagnosis is small (7% with ∼7-year follow-up), but active surveillance is required to diagnose early-stage disease.

Examining Race and Patient-Reported Outcomes After Contralateral Prophylactic Mastectomy with Reconstruction.

BACKGROUND: Little is known regarding racial differences in satisfaction and quality of life (QOL) after contralateral prophylactic mastectomy (CPM). In this study, we aim to characterize associations between race, and postoperative satisfaction and well-being, utilizing the validated BREAST-Q patient-reported outcome measure. PATIENTS AND METHODS: Patients were eligible if they were diagnosed with stage 0-III unilateral breast cancer and underwent mastectomy with immediate reconstruction at our institution between 2016 and 2022. BREAST-Q surveys were administered in routine clinical care preoperatively and postoperatively to assess QOL. We assessed whether the relationship between race, and domains of satisfaction with breasts and psychosocial well-being differed by receipt of CPM compared with unilateral mastectomy at 6 months, 1 year, 2 years, and 3 years following reconstruction. RESULTS: Of 3334 women, 2040 (61%) underwent unilateral mastectomy and 1294 (39%) underwent CPM. Compared with White and Asian women who received CPM, Black women who underwent CPM were more likely to have higher BMI (p < 0.001), undergo autologous reconstruction (p = 0.006), and receive postmastectomy radiation (PMRT) (p < 0.001). There was no association between race and domains of satisfaction of breasts or psychosocial well-being for women who underwent unilateral mastectomy (p = 0.6 and p > 0.9, respectively) or CPM (p = 0.8 and p = 0.9, respectively). PMRT was negatively associated with both satisfaction with breasts (p < 0.001) and psychosocial well-being (p = 0.007). CONCLUSIONS: Differences in satisfaction with breasts and psychosocial well-being at 3-year follow-up were not associated with race but rather treatment variables, particularly the receipt of PMRT. Further investigations with a larger and more diverse population are needed to validate these findings.

Effects of a 12-week exercise-based intervention on weight management in overweight or obese breast cancer survivors: a randomized controlled trial.

PURPOSE: Breast cancer survivors face dual challenges: long-term sequelae of treatment and the risk of recurrent disease. Furthermore, obesity and a sedentary lifestyle can complicate both challenges. We aimed to assess the effect of a 12-week exercise-based weight-management program in overweight/obese breast cancer survivors. METHODS: A two-arm, single-blinded, randomized controlled trial was conducted among 60 overweight/obese, stage 0-III breast cancer survivors. During the 12-week program, the intervention group received weekly information support, fortnightly exercise prescriptions, including aerobic and resistance exercises to perform at home, and one dietary instruction. The control group received information support about weight management and exercise. Weight, body composition, and physical fitness data were collected at baseline, postintervention, and the 3-month follow-up. RESULTS: The intervention group showed significant improvements in body weight and all adiposity indices, including body mass index, waist circumference, and %body fat, in comparison with baseline (P < 0.001) and the control group (P < 0.05). Both groups showed no significant changes in fat-free mass during the 6-month period (P > 0.05). International Physical Activity Questionnaire scores and left grip strength increased significantly in the intervention group in comparison with the baseline (P < 0.01) and the control group (P < 0.05). Right grip strength, lower-body strength, and aerobic endurance showed no significant intergroup differences (P > 0.05). CONCLUSIONS: A combination of exercise prescription and weight-loss interventions yielded clinically meaningful weight loss in overweight/obese breast cancer survivors. These findings may facilitate the incorporation of home-based exercise and weight management into breast cancer treatment and survivorship care.

COVID-19 related change in breast cancer diagnosis, stage, treatment, and case volume: 2019-2021.

PURPOSE: Evaluate the COVID-19 pandemic impact on breast cancer detection method, stage and treatment before, during and after health care restrictions. METHODS: In a retrospective tertiary cancer care center cohort, first primary breast cancer (BC) patients, years 2019-2021, were reviewed (n = 1787). Chi-square statistical comparisons of detection method (patient (PtD)/mammography (MamD), Stage (0-IV) and treatment by pre-pandemic time 1: 2019 + Q1 2020; peak-pandemic time 2: Q2-Q4 2020; pandemic time 3: Q1-Q4 2021 (Q = quarter) periods and logistic regression for odds ratios were used. RESULTS: BC case volume decreased 22% in 2020 (N = 533) (p = .001). MamD declined from 64% pre-pandemic to 58% peak-pandemic, and increased to 71% in 2021 (p < .001). PtD increased from 30 to 36% peak-pandemic and declined to 25% in 2021 (p < .001). Diagnosis of Stage 0/I BC declined peak-pandemic when screening mammography was curtailed due to lock-down mandates but rebounded above pre-pandemic levels in 2021. In adjusted regression, peak-pandemic stage 0/I BC diagnosis decreased 24% (OR = 0.76, 95% CI: 0.60, 0.96, p = .021) and increased 34% in 2021 (OR = 1.34, 95% CI: 1.06, 1.70, p = .014). Peak-pandemic neoadjuvant therapy increased from 33 to 38% (p < .001), primarily for surgical delay cases. CONCLUSIONS: The COVID-19 pandemic restricted health-care access, reduced mammography screening and created surgical delays. During the peak-pandemic time, due to restricted or no access to mammography screening, we observed a decrease in stage 0/I BC by number and proportion. Continued low case numbers represent a need to re-establish screening behavior and staffing.

Should low-risk DCIS lose the cancer label? An evidence review.

BACKGROUND: Population mammographic screening for breast cancer has led to large increases in the diagnosis and treatment of ductal carcinoma in situ (DCIS). Active surveillance has been proposed as a management strategy for low-risk DCIS to mitigate against potential overdiagnosis and overtreatment. However, clinicians and patients remain reluctant to choose active surveillance, even within a trial setting. Re-calibration of the diagnostic threshold for low-risk DCIS and/or use of a label that does not include the word 'cancer' might encourage the uptake of active surveillance and other conservative treatment options. We aimed to identify and collate relevant epidemiological evidence to inform further discussion on these ideas. METHODS: We searched PubMed and EMBASE databases for low-risk DCIS studies in four categories: (1) natural history; (2) subclinical cancer found at autopsy; (3) diagnostic reproducibility (two or more pathologist interpretations at a single time point); and (4) diagnostic drift (two or more pathologist interpretations at different time points). Where we identified a pre-existing systematic review, the search was restricted to studies published after the inclusion period of the review. Two authors screened records, extracted data, and performed risk of bias assessment. We undertook a narrative synthesis of the included evidence within each category. RESULTS: Natural History (n = 11): one systematic review and nine primary studies were included, but only five provided evidence on the prognosis of women with low-risk DCIS. These studies reported that women with low-risk DCIS had comparable outcomes whether or not they had surgery. The risk of invasive breast cancer in patients with low-risk DCIS ranged from 6.5% (7.5 years) to 10.8% (10 years). The risk of dying from breast cancer in patients with low-risk DCIS ranged from 1.2 to 2.2% (10 years). Subclinical cancer at autopsy (n = 1): one systematic review of 13 studies estimated the mean prevalence of subclinical in situ breast cancer to be 8.9%. Diagnostic reproducibility (n = 13): two systematic reviews and 11 primary studies found at most moderate agreement in differentiating low-grade DCIS from other diagnoses. Diagnostic drift: no studies found. CONCLUSION: Epidemiological evidence supports consideration of relabelling and/or recalibrating diagnostic thresholds for low-risk DCIS. Such diagnostic changes would need agreement on the definition of low-risk DCIS and improved diagnostic reproducibility.

Does Non-Classic Lobular Carcinoma In Situ at the Lumpectomy Margin Increase Local Recurrence?

BACKGROUND: The clinical significance of nonclassic, lobular carcinoma in situ (NC-LCIS) at the surgical margin of excisions for invasive cancer is unknown. We sought to determine whether NC-LCIS at or near the margin in the setting of a concurrent invasive carcinoma is associated with risk of ipsilateral breast tumor recurrence (IBTR) and locoregional recurrence (LRR). METHODS: Patients with stage 0-III breast cancer and NC-LCIS who underwent lumpectomy between January 2010 and January 2022 at a single institution were retrospectively identified. NC-LCIS margins were stratified as <2 mm, ≥2 mm, or within shave margin. Rates of IBTR and LRR were examined. RESULTS: A total of 511 female patients (median age 60 years [interquartile range (IQR) 52-69]) with NC-LCIS and an associated ipsilateral breast cancer with a median follow-up of 3.4 years (IQR 2.0-5.9) were identified. Final margins for NC-LCIS were ≥2 mm in 348 patients (68%), <2 mm in 37 (7.2%), and within shave margin in 126 (24.6%). Crude incidence of IBTR was 3.3% (n = 17) and that of LRR was 4.9% (n = 25). There was no difference in the crude rate of IBTR by NC-LCIS margin status (IBTR rate: 3.7% ≥2 mm, 0% <2 mm, 3.2% within shave margin, p = 0.8) nor in LRR (LRR rate: 4.9% ≥2 mm, 2.7% <2 mm, 5.6% within shave margin, p = 0.9). CONCLUSIONS: For completely excised invasive breast cancers associated with NC-LCIS, extent of margin width for NC-LCIS was not associated with a difference in IBTR or LRR. These data suggest that the decision to perform reexcision of margin after lumpectomy should be driven by the invasive cancer, rather than the NC-LCIS margin.

The effectiveness of an ultrafast breast MRI protocol in the differentiation of benign and malignant breast lesions.

AIM: To evaluate the effectiveness of an ultrafast breast magnetic resonance imaging (MRI) protocol in differentiating benign and malignant breast lesions. MATERIALS AND METHODS: Fifty-four patients with Breast Imaging Reporting and Data System (BI-RADS) 4 or 5 lesions were recruited between July 2020 to May 2021. A standard breast MRI was performed with the inclusion of the ultrafast protocol between the unenhanced sequence and the first contrast-enhanced sequence. Three radiologists performed image interpretation in consensus. Ultrafast kinetic parameters analysed included the maximum slope (MS), time to enhancement (TTE), and arteriovenous index (AVI). These parameters were compared using receiver operating characteristics with p-values of <0.05 considered to indicate statistical significance. RESULTS: Eighty-three histopathological proven lesions from 54 patients (mean age 53.87 years, SD 12.34, range 26-78 years) were analysed. Forty-one per cent (n=34) were benign and 59% (n=49) were malignant. All malignant and 38.2% (n=13) benign lesions were visualised on the ultrafast protocol. Of the malignant lesions, 77.6% (n=53) were invasive ductal carcinoma (IDC) and 18.4% (n=9) were ductal carcinoma in situ (DCIS). The MS for malignant lesions (13.27%/s) were significantly larger than for benign (5.45%/s; p<0.0001). No significant differences were seen for TTE and AVI. The area under the ROC curve (AUC) for the MS, TTE, and AVI were 0.836, 0.647, and 0.684, respectively. Different types of invasive carcinoma had similar MS and TTE. The MS of high-grade DCIS was also similar to that of IDC. Lower MS values were observed for low-grade (5.3%/s) compared to high-grade DCIS (14.8%/s) but the results were not significant statistically. CONCLUSION: The ultrafast protocol showed potential to discriminate between malignant and benign breast lesions with high accuracy using MS.

Management of Lobular Neoplasia Diagnosed by Core Biopsy.

Lobular neoplasia (LN) involves proliferative changes within the breast lobules. LN is divided into lobular carcinoma in situ (LCIS) and atypical lobular hyperplasia (ALH). LCIS can be further subdivided into three subtypes: classic LCIS, pleomorphic LCIS, and LCIS with necrosis (florid type). Because classic LCIS is now considered as a benign etiology, current guidelines recommend close follow-up with imaging versus surgical excision. The goal of our study was to determine if the diagnosis of classic LN on core needle biopsy (CNB) merits surgical excision. This is a retrospective, observational study conducted at Mount Auburn Hospital, Cambridge, MA, from May 17, 2017, through June 30, 2020. We reviewed the data of breast biopsies conducted at our hospital over this period and included patients who were diagnosed with classic LN (LCIS and/or ALH) and excluded patients having any other atypical lesions on CNB. All known cancer patients were excluded. Of the 2707 CNBs performed during the study period, we identified 68 women who were diagnosed with ALH or LCIS on CNB. CNB was performed for an abnormal mammogram in the majority of patients (60; 88%) while 7(10.3%) had an abnormal breast magnetic resonance imaging study (MRI), and 1 had an abnormal ultrasound (US). A total of 58 patients (85%) underwent excisional biopsy, of which 3 (5.2%) showed malignancy, including 2 cases of DCIS and 1 invasive carcinoma. In addition, there was 1 case (1.7%) with pleomorphic LCIS and 11 cases with ADH (15.5%). The management of LN found on core biopsy is evolving, with some advocating surgical excision and others recommending observation. Our data show a change in diagnosis with excisional biopsy in 13 (22.4%) of patients with 2 cases of DCIS, 1 invasive carcinoma, 1 pleomorphic LCIS, and 9 cases of ADH, diagnosed on excisional biopsy. While ALH and classic LCIS are considered benign, the choice of ongoing surveillance versus excisional biopsy should be made with shared decision making with the patient, with consideration of personal and family history, as well as patient preferences.

Accuracy of the Breast Cancer Surveillance Consortium Model Among Women with LCIS.

PURPOSE: The Breast Cancer Surveillance Consortium (BCSC) model predicts risk of invasive breast cancer risk based on age, race, family history, breast density, and history of benign breast disease, including lobular carcinoma in situ (LCIS). However, validation studies for this model included few women with LCIS. We sought to evaluate the accuracy of the BCSC model among this cohort. METHODS: Women with LCIS diagnosed between 1983 and 2017 were identified from a prospectively maintained database. The BCSC score was calculated; those with prior breast cancer, unknown breast density, age < 35 years or > 74 years, or with history of chemoprevention use were excluded. The Kaplan-Meier method was used to estimate incidence rates. Time-dependent receiver operating characteristic (ROC) analysis was used to analyze the discriminative capacity of the model. RESULTS: 1302 women with LCIS were included. At a median follow-up of 7 years, 152 women (12%) developed invasive cancer (6 with bilateral disease). Cumulative incidences of invasive breast cancer were 7.1% (95% CI 5.6-8.7) and 13.3% (95% CI 10.9-15.6), respectively, and the median BCSC risk scores were 4.9 and 10.4, respectively, at 5 and 10 years. The median 10-year BCSC score was significantly lower than the 10-year Tyrer-Cuzick score (10.4 vs 20.8, p < 0.001). The ROC curve scores (AUC) for BCSC at 5 and 10 years were 0.59 (95% CI 0.52-0.66) and 0.58 (95% CI 0.52-0.64), respectively. CONCLUSION: The BCSC model has moderate accuracy in predicting invasive breast cancer risk among women with LCIS with fair discrimination for risk prediction between individuals.

Synchronous and metachronous bilateral breast cancer among women with a history of lobular carcinoma in situ.

PURPOSE: Lobular carcinoma in situ (LCIS) confers increased cancer risk in either breast, but it remains unclear if this population is at increased risk for bilateral breast cancer (BC) development. Here we report bilateral BC incidence among women with a history of LCIS. METHODS: Women with classic-type LCIS diagnosed from 1980 to 2017 who developed unilateral BC (UBC) or bilateral BC were identified. Bilateral BC was categorized as synchronous (bilateral BC diagnosed < 6 months apart; SBBC) or metachronous (bilateral BC diagnosed ≥ 6 months apart; MBBC). Five-year incidence rates of bilateral BC among this population were evaluated. Comparisons were made to identify factors associated with bilateral BC. RESULTS: At 7 years' median follow-up, 249/1651 (15%) women with LCIS developed BC; 34 with bilateral BC (2%). There were no clinicopathologic feature differences between those with UBC and bilateral BC. SBBC occurred in 18 without significant differences versus UBC. Among 211 with UBC and a contralateral breast at risk, 16 developed MBBC at a median follow-up of 3 years. MBBC patients were less likely to receive endocrine therapy and more likely to receive chemotherapy versus UBC. Tumor histology was not associated with MBBC. Estimated 5-year MBBC risk was 6.4%. Index estrogen/progesterone receptor positivity and endocrine therapy were the only factors associated with MBBC risk. CONCLUSION: Bilateral BC occurred in 2% of women with LCIS history at median follow-up of 7 years. Similar to the general BC population, a decrease in MBBC is seen among women with a history of LCIS who develop hormone receptor-positive disease and those who receive endocrine therapy, highlighting the protective effects of this treatment.

High-risk lesions in the breast diagnosed by MRI-guided core biopsy: upgrade rates and features associated with malignancy.

PURPOSE: This study assessed the upgrade rates of high-risk lesions (HRLs) in the breast diagnosed by MRI-guided core biopsy and evaluated imaging and clinical features associated with upgrade to malignancy. METHODS: This IRB-approved, retrospective study included MRI-guided breast biopsy exams yielding HRLs from August 1, 2011, to August 31, 2020. HRLs included atypical ductal hyperplasia (ADH), lobular carcinoma in situ (LCIS), atypical lobular hyperplasia (ALH), radial scar, and papilloma. Only lesions that underwent excision or at least 2 years of MRI imaging follow-up were included. For each HRL, patient history, imaging features, and outcomes were recorded. RESULTS: Seventy-two lesions in 65 patients were included in the study, with 8/72 (11.1%) of the lesions upgraded to malignancy. Upgrade rates were 16.7% (2/12) for ADH, 100% (1/1) for pleomorphic LCIS, 40% (2/5) for other LCIS, 0% (0/19) for ALH, 0% (0/18) for papilloma, and 0% (0/7) for radial scar/complex sclerosing lesion. Additionally, two cases of marked ADH bordering on DCIS and one case of marked ALH bordering on LCIS, were upgraded. Lesions were more likely to be upgraded if they presented as T2 hypointense (versus isotense, OR 6.46, 95% CI 1.27-32.92) or as linear or segmental non-mass enhancement (NME, versus focal or regional, p = 0.008). CONCLUSION: Our data support the recommendation that ADH and LCIS on MRI-guided biopsy warrant surgical excision due to high upgrade rates. HRLs that present as T2 hypointense, or as linear or segmental NME, should be viewed with suspicion as these were associated with higher upgrade rates to malignancy.

Invasive lobular carcinoma with extracellular mucin (ILCEM): clinicopathologic and molecular characterization of a rare entity.

Invasive lobular carcinoma with extracellular mucin (ILCEM) is a rare histologic subtype of breast cancer. Little is known about the pathologic or genomic signatures that distinguish ILCEM from classic invasive lobular carcinoma (ILC) or mucinous carcinoma. We studied 17 breast cancers with lobular morphology and extracellular mucin. Thirteen tumors with sufficient tissue for DNA extraction were analyzed by a next generation sequencing (NGS) assay that interrogates 447 genes for mutations and copy number variations (CNVs). Median patient age was 66 yrs (range: 31-77 yrs). Sixteen patients presented with masses, 7 of which were >2 cm. Seven patients had lymph node metastases. The cases of ILCEM were moderately (n = 13) or poorly differentiated (n = 4), frequently exhibiting variant morphology that has not been previously described or emphasized, including grade 3 nuclei (n = 11), diffuse signet ring cells (n = 10), solid growth (n = 4), tumor necrosis (n = 3) or apocrine features (n = 2). All tumors showed absent or reduced membranous E-cadherin expression. Concurrent lobular carcinoma in situ (LCIS) was seen in 11/17 cases, 1 of which was a striking example of signet ring cell LCIS with extracellular mucin. Receptor profiles were ER+/HER2- (n = 15) and ER+/HER2+ (n = 2). With a median follow-up of 83.5 months (range: 3-171 months) in 12 patients with available information, 8 patients had recurrences resulting in 4 cancer-related deaths. The most common CNVs were 16q loss (n = 11) and 1q gain (n = 9). CDH1 gene-level alterations were detected in all but one case, including frameshift (n = 7), nonsense (n = 2), and donor splice site (n = 1) mutations and indels (n = 2). Recurrent mutations were also seen in PIK3CA (n = 3), POLQ (n = 3), TP53 (n = 3), ERBB3 (n = 3), ERBB2 (n = 2), and RUNX1 (n = 2). Genes with recurrent amplifications included GATA3 (n = 4), FOXA1 (n = 3), CCND1 (n = 2). Our data highlights ILCEM as a distinct variant of ILC that often presents with higher-grade and variant morphologic features and is associated with an aggressive clinical course. NGS data support an overall lobular-type molecular profile and reveal potentially targetable alterations in a subset of cases with recurrence.

Comparison of Outcomes for Classic-Type Lobular Carcinoma In Situ Managed with Surgical Excision After Core Biopsy Versus Observation.

BACKGROUND: Studies report low upgrade rates following excision for classic-type lobular carcinoma in situ (LCIS) with radiologic-pathologic concordance. Thus, in the absence of other high-risk lesions, observation has become standard. We report long-term outcomes of excision versus observation following a core biopsy diagnosis of classic-type LCIS. METHODS: Women with LCIS treated from 2013-2020 and managed with excision or observation were identified from a prospective database. Women with cancer upgrade at excision or history of cancer were excluded. We compared rates and characteristics of subsequent breast cancers by clinical management strategy. RESULTS: Of 312 women, 170 (54%) underwent excision and 142 (46%) were managed with observation. Among the excision group, 36 of 170 (21%) had radiologic-pathologic concordant LCIS without other high-risk lesions, mass, or symptoms (concordant LCIS excision group). Overall, at 3.1 years median follow-up, 11 (6.5%) women managed with excision and 11 (7.7%) women managed with observation developed cancer. Cancer development was not associated with management choice (overall excision cohort vs. observation group [p = 0.8]) and did not differ between the concordant LCIS excision and observation groups (p > 0.9). The 5-year cancer development rate was 8.9% (95% confidence interval [CI]: 2.3-31.6%) in the concordant LCIS excision group and 10.3% (95% CI 5.5-18.6%) in the observation group. CONCLUSIONS: No difference in breast cancer rates existed among women with a core-biopsy diagnosis of classic-type LCIS managed with excision or observation. These data support management of LCIS as a risk factor, with consideration of chemoprophylaxis, rather than as an indication for surgical excision.

Presence of Non-classic LCIS Is Not a Contraindication to Breast Conservation in Patients with Concomitant Invasive Breast Cancer or DCIS.

BACKGROUND: Non-classic lobular carcinoma in situ (NC-LCIS) represents a spectrum of lesions, histologically distinct from classic LCIS (C-LCIS) and ductal carcinoma in situ (DCIS). Several studies have reported on the safety of breast conservation (BCS) in patients with DCIS or invasive breast cancer and concomitant C-LCIS, yet there are no data addressing this question for patients with concomitant NC-LCIS. We evaluated local recurrence (LR) after BCS in patients with DCIS or invasive cancer and concomitant NC-LCIS. PATIENTS AND METHODS: We searched institutional databases using natural language processing to identify patients with DCIS or invasive breast cancer and concomitant NC-LCIS treated with BCS between 2000 and 2015. Charts were reviewed to collect demographics, disease and treatment details, and recurrence events. All results represent descriptive analyses. RESULTS: We identified 71 patients with DCIS (n = 13) or invasive cancer (n = 58) and concomitant NC-LCIS treated with BCS. Median patient age was 59 years (33-77 years), and median invasive tumor size was 1.2 cm (0.1-6.9 cm); 62% of DCIS and 79% of invasive cancer patients had hormone receptor (HR)-positive disease. Among DCIS patients, seven (54%) received radiation and none hormonal therapy. Among those with invasive cancer, 52 (90%) received radiation, 17 (29%) received chemotherapy and 44 of 55 with HR-positive disease (78%) received hormonal therapy. At median follow-up of 79 months (1-265 months), the LR rate was 8% and 2% among patients with DCIS and invasive cancer, respectively. CONCLUSION: NC-LCIS is rarely present in association with DCIS or invasive cancer, and it does not appear to impact LR outcomes following BCS.

Risk of Lobular Neoplasia Upgrade with Synchronous Carcinoma.

BACKGROUND: Atypical lobular hyperplasia (ALH) and classic lobular carcinoma in situ encompass a spectrum of proliferative lesions known as lobular neoplasia (LN). When imaging-concordant and found in isolation on core needle biopsy (CNB), LN infrequently upgrades to carcinoma on surgical excision, and routine excision is not indicated. Upgrade rates in the setting of synchronous carcinoma are not well studied. PATIENTS AND METHODS: Patients with radiology-pathology concordant synchronous LN and separately biopsied ipsilateral (n = 35) or contralateral (n = 15) carcinoma who underwent excision between 2010 and 2021 were retrospectively identified. Frequency of upgrade, to either invasive or in situ carcinoma, was quantified, and factors associated with upgrade were assessed using Fisher's exact test. RESULTS: The median age was 55 (range 33-74) years. The upgrade rate of LN was 6% and not significantly different between ipsilateral (2.9%) and contralateral (13.3%) carcinoma (p = 0.15). All upgraded LN lesions were ALH on CNB and detected as non-mass enhancement on magnetic resonance imaging (MRI). No additional disease was demonstrated after excision at the site of the original LN CNB in 22.9% (8 out of 35) of ipsilateral and 13.3% (2 out of 15) of contralateral patients. Upgrade was not associated with family history, menopausal status, imaging modality used to detect LN, or extent of LN on CNB (p > 0.05). CONCLUSIONS: Our results demonstrate a low upgrade rate (6%) in our study cohort of LN with synchronous ipsilateral or contralateral carcinoma, which suggests that not all LN mandates excision with synchronous carcinoma. Larger, multi-institution studies are needed to validate these findings.

Atypical Lobular Hyperplasia and Classic Lobular Carcinoma In Situ Can Be Safely Managed Without Surgical Excision.

BACKGROUND: Based on modern series demonstrating low upgrade rates for pure lobular neoplasia (LN) diagnosed on core needle biopsy (CNB), our institution no longer recommends routine excision, provided imaging is concordant. This study describes outcomes in patients managed without surgical excision. METHODS: From an institutional database, we identified all patients with a diagnosis of pure atypical lobular hyperplasia and/or classic lobular carcinoma in situ on CNB managed without surgical excision (i.e., conservative management) from 2015 to 2019. The primary outcome of interest was failure of conservative management, defined as development of ipsilateral same-quadrant ductal carcinoma in situ or invasive breast cancer within 2 years of CNB, or need for ipsilateral same-quadrant excisional biopsy. We also evaluated rates of ipsilateral same-quadrant CNB during follow-up. RESULTS: Among 96 pure LN lesions on CNB since 2015, 80 (83%) were managed without surgical excision. Median follow-up was 27 months (IQR: 16-28), with only 2 (2%) patients lost to follow-up. No patients developed an ipsilateral, same-quadrant breast cancer. The 3-year risk of conservative management failure was 6.2% (95% CI 2.3-15.7%). All failures were a result of need for excisional biopsy due to progressive imaging abnormalities at the initial CNB site, with benign final pathology. The 3-year risk of ipsilateral same-quadrant CNB was 9.2% (95% CI 3.8-21.5%). CONCLUSION: Non-surgical management of pure LN is safe, and the likelihood of requiring subsequent surgical excision or repeat CNB during follow-up is low. These data provide reassurance that routine excision of pure LN in the setting of radiologic-pathologic concordance is not required.

The Influence of Body Mass Index on the Histopathology and Outcomes of Patients Diagnosed with Atypical Breast Lesions.

BACKGROUND: Multiple studies have demonstrated a link between obesity and breast cancer; however, the potential association between obesity and atypical high-risk breast lesions has not been well characterized. We sought to evaluate the characteristics and clinical outcomes of patients with breast atypia based on a woman's body mass index (BMI). METHODS: We retrospectively identified adult women diagnosed with atypical ductal hyperplasia (ADH), atypical lobular hyperplasia (ALH), and/or lobular carcinoma in situ (LCIS) at a single institution from 2008 to 2017. BMI groups were defined as a BMI 18.5 to < 30 or BMI ≥ 30 (obese). Adjusted logistic regression was used to estimate the association of BMI group with the odds of (1) upstage to cancer after atypia on needle biopsy, and (2) subsequent diagnosis of breast cancer. RESULTS: Breast atypia was identified in 503 patients (most advanced atypia: 74.8% ADH, 4.6% ALH, 20.7% LCIS), and 41% of these patients were classified as obese. After adjustment, BMI group was not associated with upstage to breast cancer at surgical excision following needle biopsy (p = 0.16) or development of a subsequent breast cancer (p = 0.08). For those upstaged to breast cancer at the time of surgical excision, or those who developed a subsequent malignancy, tumor subtype, grade and stage were not associated with BMI group (p > 0.05). CONCLUSION: In a large cohort of patients diagnosed with atypical breast histology, the risk of upstaging and/or subsequent progression to a breast malignancy was not associated with BMI. Factors other than obesity may influence breast cancer risk.

Dataset for pathology reporting of ductal carcinoma in situ, variants of lobular carcinoma in situ and low-grade lesions: recommendations from the International Collaboration on Cancer Reporting (ICCR).

AIMS: To describe a new international dataset for pathology reporting of ductal carcinoma in situ (DCIS), variants of lobular carcinoma in situ (LCIS) and low-grade lesions (encapsulated papillary carcinoma, solid papillary carcinoma in situ, Paget's disease) produced by the International Collaboration on Cancer Reporting (ICCR). METHODS AND RESULTS: The ICCR, a global alliance of pathology bodies, uses a rigorous and efficient process for the development of evidence-based, structured datasets for pathology reporting of common cancers. Their aim is to support quality pathology reporting and engender understanding between the breast surgeon, pathologist, and oncologist for optimal and uniform patient management globally. Here we describe the dataset for DCIS, some variants of LCIS (namely the pleomorphic and the florid variants), and low-grade lesions by a multidisciplinary panel of internationally recognized experts. The agreed dataset comprises 12 core (required) and five noncore (recommended) elements suitable for both developed and low-income jurisdictions, derived from a review of current evidence. Areas of contention were addressed using a pragmatic approach in the absence of evidence. Use of all core elements is the minimum reporting standard for any individual case. Commentary is provided, explaining each element's clinical relevance, definitions to be applied where appropriate for the agreed list of value options and the rationale for considering the element as core or noncore. CONCLUSION: This first internationally agreed dataset for DCIS, variants of LCIS, and low-grade lesions reporting will enable their standardization of pathology reporting and enhance clinicopathological communication leading to improved patient outcomes. Widespread adoption will also facilitate international comparisons, multinational clinical trials, and help to improve the management of breast disease globally.