Preoperative factors that predict pathologic nodal involvement in early-stage HER2+ breast cancer: selecting cT1cN0 patients for treatment with neoadjuvant chemotherapy versus upfront surgery.

PURPOSE: The goal of this study was to identify the preoperative predictors of pathologic nodal metastases (pN+) in cT1cN0 HER2+ breast cancer undergoing upfront surgery. METHODS: We retrospectively reviewed data from women with cT1-T2N0 HER2+ breast cancer treated with neoadjuvant therapy (NAC) or upfront surgery at our institution between 2012 and 2023. Factors associated with management strategy were evaluated, and in those undergoing upfront surgery, univariate analyses were performed to identify the clinicopathologic factors associated with nodal metastases. RESULTS: Overall, 255 women with cT1-T2N0 HER2+ breast cancer met inclusion criteria, including 170 (68.6%) upfront surgery patients and 85 (31.4%) who underwent NAC. The median age at diagnosis was 59 years (range, 27-90 years). Younger age, larger clinical tumor size, high-grade disease, ER-PR-HER2+ subtype, and year of diagnosis after 2019 were significantly associated with receipt of NAC (p < 0.05). In those undergoing upfront surgery, 25.3% were pN+ , including 32.5% of cT1cN0 tumors. Factors associated with nodal involvement included age under 50, larger clinical tumor size, lymphovascular invasion (LVI), multifocality/multicentricity, and abnormal lymph nodes on axillary ultrasound (p < 0.05). In subset analysis of cT1cN0 HER2+ cases, LVI remained the strongest predictor of pN + disease (73.3% vs. 22.6%, p < 0.001). Patients with cT1cN0 HER2+ breast cancer under 50 years had a 47.1% likelihood of pN+ disease. CONCLUSION: Patients with cT1cN0 breast cancer have a 32.5% likelihood of nodal metastases, with higher incidence with younger age, LVI, multifocality/multicentricity, and abnormal axillary ultrasound. The presence of these factors may identify the patients who would benefit from treatment with neoadjuvant chemotherapy.

Awareness and Candidacy for Endocrine Prevention and Risk Reducing Mastectomy in Unaffected High-Risk Women Referred for Breast Cancer Risk Assessment.

INTRODUCTION: Primary prevention of breast cancer in women at elevated risk includes several strategies such as endocrine prevention and risk-reducing mastectomy (RRM). The objective of this study was to evaluate awareness of different preventive strategies across high-risk subgroups. PATIENTS AND METHODS: Women referred for high risk evaluation between 2020 and 2023 completed an initial risk-assessment questionnaire that included questions around perceived lifetime risk and consideration of preventive strategies. One-way analysis of variance (ANOVA) and chi-squared tests were used to compare differences across different high-risk subgroups. RESULTS: 482 women with a median age of 43 years (20-79 years) met inclusion criteria; 183 (38.0%) germline pathogenic variant carriers (GPV), 90 (18.7%) with high-risk lesions (HRL) on breast biopsy, and 209 (43.4%) with strong family history (FH) without a known genetic predisposition. Most high-risk women reported that they had considered increased screening and surveillance (83.7%) and lifestyle strategies (80.6%), while fewer patients had considered RRM (39.8%) and endocrine prevention (27.0%). Prior to initial consultation, RRM was more commonly considered in GPV carriers (59.4%) relative to those with HRL (33.3%) or strong FH (26.3%, p < 0.001). Based on current guidelines, 206 (43%) patients were deemed eligible for endocrine prevention, including 80.5% with HRL and 39.0% with strong FH. Prior consideration of endocrine prevention was highest in patients with HRL and significantly lower in those with strong FH (47.2% HRL versus 31.1% GPV versus 18.7% FH, p = 0.001). CONCLUSIONS: Endocrine prevention is the least considered preventive option for high-risk women, despite eligibility in a significant proportion of those presenting with HRL or strong FH.

Axillary Lymph Node Ultrasound Following Neoadjuvant Chemotherapy in Biopsy-Proven Node-Positive Breast Cancer: Results from the SN FNAC Study.

BACKGROUND: The sentinel node biopsy following neoadjuvant chemotherapy (SN FNAC) study has shown that in node-positive (N+) breast cancer, sentinel node biopsy (SNB) can be performed following neoadjuvant chemotherapy (NAC), with a low false negative rate (FNR = 8.4%). A secondary endpoint of the SN FNAC study was to determine whether axillary ultrasound (AxUS) could predict axillary pathological complete response (ypN0) and increase the accuracy of SNB. METHODS: The SN FNAC trial is a study of patients with biopsy-proven N+ breast cancer who underwent SNB followed by completion node dissection. All patients had AxUS following NAC and the axillary nodes were classified as either positive (AxUS+) or negative (AxUS-). AxUS was compared with the final axillary pathology results. RESULTS: There was no statistical difference in the baseline characteristics of patients with AxUS+ versus those with AxUS-. Overall, 82.5% (47/57) of AxUS+ patients had residual positive lymph nodes (ypN+) at surgery and 53.8% (42/78) of AxUS- patients had ypN+. Post NAC AxUS sensitivity was 52.8%, specificity 78.3%, and negative predictive value 46.2%. AxUS FNR was 47.2%, versus 8.4% for SNB. If post-NAC AxUS- was used to select patients for SNB, FNR would decrease from 8.4 to 2.7%. However, using post-NAC AxUS in addition to SNB as an indication for ALND would have led to unnecessary ALND in 7.8% of all patients. CONCLUSION: AxUS is not appropriate as a standalone staging procedure, and SNB itself is sufficient to assess the axilla post NAC in patients who present with N+ breast cancer.

Oncologic safety of breast conserving surgery after neoadjuvant chemotherapy in patients with multiple ipsilateral breast cancer: A retrospective multi-institutional cohort study.

INTRODUCTION: The recent ACOSOG Z11102 trial demonstrated low recurrence rates with breast conserving surgery (BCS) in women with multiple ipsilateral breast cancers (MIBC). Questions remain regarding the oncologic safety of BCS in women with MIBC receiving neoadjuvant chemotherapy (NAC). METHODS: We conducted a retrospective cohort study of adult patients who underwent BCS following NAC for stage I-III breast cancer from 2012 to 2021 at two academic centers. Descriptive statistics were used to summarize the data and the Kaplan-Meier method was used to provide estimates for recurrence and survival outcomes. MIBC was defined as ≥2 foci of malignancy. RESULTS: A total of 544 patients were included; 29.4% (n = 160) ER+/HER2-, 17.7% (n = 96) ER+/HER2+, 18.2% (n = 99) ER-/HER2+, and 34.7% (n = 189) with ER-/HER2-disease. Overall, 80.5% (n = 438) had unifocal breast cancer while 19.5% (n = 106) had MIBC. Of patients with MIBC, 90.6% (n = 96) had multifocal and 9.4% (n = 10) had multicentric disease. Pathologic complete response was achieved in 41.1% of patients with MIBC versus 41.5% of patients with unifocal disease (p = 0.94). At a median follow-up of 55 months (IQR 32-83); 4.8% of patients in the unifocal group and 4.7% of patients in the MIBC group had had a local recurrence (p = 0.97). There was no difference in 5-year local recurrence-free survival (p = 0.92), recurrence-free survival (p = 0.06), or overall survival (p = 0.07) between the groups. CONCLUSION: In this large cohort of women undergoing BCS post-NAC, there was no significant difference in in breast tumor recurrence or survival outcomes between patients with unifocal disease and those with MIBC.

Timing of genetic testing in BRCA1/2 and PALB2-Associated breast cancer: Preoperative result disclosure increases uptake of risk-reducing mastectomy and reduces unnecessary exposure to radiotherapy.

INTRODUCTION: The impact of timing of genetic testing on uptake of risk reducing mastectomy (RRM) in affected female BRCA1/2 or PALB2 carriers remains an area of evolving interest, particularly with the introduction of mainstream genetic testing initiatives. METHODS: Women with stage I-III breast cancer and a confirmed germline pathogenic variant in BRCA1/2 or PALB2 between 2000 and 2023 were identified from an institutional genetics database. Uptake of RRM was evaluated according to disclosure of genetic testing results before or after index surgery for a first diagnosis of breast cancer. RESULTS: The cohort included 287 female BRCA1/2 or PALB2 carriers with a median age of 44 years (IQR, 36-52). Overall, 155 (54 %) carriers received genetic testing results before and 132 (46 %) after index breast surgery. Receipt of genetic testing results before surgery was associated with a higher rate of index bilateral mastectomy (58.7 % vs. 7.6 %, p < 0.001) and a commensurate decrease in adjuvant radiation (41.9 % vs. 74.2 %, p < 0.001). At a median follow up of 4.4 years after genetic testing, 219 (76.3 %) affected carriers had undergone bilateral RRM, including 83.9 % with preoperative knowledge and 67.4 % of patients with postoperative knowledge of their germline pathogenic variant (log rank, p < 0.001). On multivariate regression, disclosure of genetic testing results before index breast surgery was independently associated with long-term uptake of bilateral mastectomy (HR 1.69, 95 % CI 1.21-2.38). CONCLUSION: Genetic testing results delivered prior to index breast surgery increase uptake of bilateral RRM in affected BRCA1/2 and PALB2 carriers. Efforts to mainstream genetic testing would help optimize surgical decision-making.

Surgical and Oncologic Outcomes of Nipple-Sparing Mastectomy for a Cohort of Breast Cancer Patients, Including Cases with High-Risk Features.

BACKGROUND: Nipple-sparing mastectomy (NSM) remains controversial in patients with high-risk breast cancer. The objective of this study was to assess surgical and oncologic outcomes of NSM and to evaluate associations of outcomes with high-risk features. METHODS: A retrospective review was conducted of all NSM cases performed for breast cancer at 2 academic cancer centers between January 2013 and August 2018. RESULTS: Of the 175 patients who underwent NSM, 13 (7.4%) had locally advanced breast cancer (LABC), 52 (29.2%) had previous neoadjuvant chemotherapy, 21 (12.0%) had previous radiation therapy, 40 (22.8%) received postmastectomy radiation, 27 (15.4%) had de-epithelialized skin reduction, and 13 (7.4%) had free nipple grafting. The median duration of follow-up was 24 months. Nipple necrosis (4 cases; 2.2%) was associated with previous radiation (9.5%; P = .018), skin reduction (11.1%; P = .001), and nipple grafting (15.4%; P = .001). The nipple-areolar complex margin (NAC) was involved with invasive disease in 1 case. Local recurrence occurred in 8 cases (4.6%), with 1 in-NAC recurrence. Overall survival was 98.3%, and disease-free survival (DFS) was 88.6%. LABC was associated with worse DFS (hazard ratio, 4.28; P = .011), with all 4 recurrences being distant. CONCLUSIONS: Previous radiation, skin reduction, and nipple grafting are associated with an increased risk of NAC necrosis. None of these should be considered absolute contraindications, but patients should be counseled appropriately. Although LABC is associated with worse DFS, relapses are systemic. Longer follow-up is needed to establish oncologic safety in unselected breast cancer patients.