Selective Elimination of Breast Surgery for Invasive Breast Cancer: A Nonrandomized Clinical Trial.

Importance: Neoadjuvant systemic therapy (NST) has been associated with pathologic complete response (pCR) in up to 60% of breast cancers (BCs). The findings of this trial question the necessity of surgery. Objective: To report preplanned 5-year efficacy outcomes evaluating radiotherapy alone without breast surgery in patients selected with image-guided vacuum assisted biopsy (VAB). Design, Setting, and Participants: This single-arm, prospective, phase 2 nonrandomized clinical trial was conducted at 7 US medical centers and included women 40 years or older with cT1-2N0-1M0 ERBB2-positive (formerly HER2-positive) or triple-negative invasive BC who showed residual breast lesions after NST of less than 2 cm on imaging. Enrollment was from March 6, 2017, to November 9, 2021. Data analysis was from October to December 2024. Intervention: Image-guided VAB of the tumor bed (9G with a minimum of 12 cores) was performed after standard NST. Patients with clinically node-negative disease at diagnosis and no residual cancer in the breast on post-NST VAB underwent whole-breast radiotherapy with a boost without breast or axillary surgery. Patients with initial documented nodal disease and a breast pCR on VAB underwent targeted axillary dissection, while those with residual cancer when undergoing VAB had standard breast and axillary surgery. Patients were monitored with physical examinations and mammography every 6 months. Main Outcome Measures: The primary outcome was ipsilateral breast tumor recurrence. Results: Fifty patients (median [IQR] age, 62 [55-77] years) were enrolled and underwent post-NST VAB. Twenty-nine (58%) and 21 (42%) patients had ERBB2-positive and triple-negative invasive BC, respectively. Breast pCR on VAB was identified in 31 patients (62%; 95% CI, 47.2%-75.34%), and axillary pCR was identified among all 8 patients with initial nodal metastases and breast pCR on VAB who underwent targeted axillary dissection. At a median follow-up of 55.4 (IQR, 44.0-63.5) months, the ipsilateral breast tumor recurrence rate was 0%, and disease-free and overall survival rates were 100% for patients without breast surgery. Conclusions and Relevance: The results of this nonrandomized clinical trial that reported preplanned 5-year outcomes suggest that omission of breast surgery in select patients after NST may be feasible, with no recurrences seen. More confirmatory studies are necessary before this new approach alters surgical practice. Trial Registration: ClinicalTrials.gov Identifier: NCT02945579.