243MO - Omission of breast surgery after neoadjuvant systemic therapy for invasive cancer: Three-year preplanned primary-endpoint on a phase II multicentre prospective trial

Background

Neoadjuvant systemic therapy (NST) for triple-negative breast cancer (TNBC) and HER2+ breast cancer (HER2+BC) yields a pathol-ogic complete response (pCR) in approximately 60% of patients. A pCR to NST predicts an excellent prognosis and can be accurately determined by percutaneous image-guided vacuum-assisted core biopsy (VACB). Radiotherapy alone, without breast surgery after NST among patients who had a VACB–determined pCR was evaluated in the feasibility phase (Johnson et al. JACS 2023 ), 2-year pre-planned primary outcome (Kuerer et al Lancet Onc 2022 ), the 32.4 mo patient reported outcomes (Johnson et al SSO 2023 ) and now at the preplanned 3-year primary endpoint.

Methods

This multicentre phase II clinical trial enrolled women aged ≥40 years with unicentric cT1-2N0-1M0 TNBC or HER2+BC and a residual breast lesion <2 cm on imaging after NST. One biopsy was obtained by 9G image-guided VACB containing a minimum of 12 cores from the tumour bed. If no invasive/in situ disease was identified, breast surgery was omitted, and patients underwent whole-breast radiotherapy/boost. Primary outcome was ipsilateral breast tumour recurrence (IBTR) rate and secondary outcomes included evaluation of baseline and longitudinal obtained circulating tumor cells (CTCs) in a total of 33 blood samples and patient-reported outcomes.

Results

During 2017-2021 50 total patients were enrolled and underwent VACB following NST. The mean age was 60·4 years (SD 7·8); 21 patients had TNBC and 29 had HER2+BC. Mean imaging final tumour size after NST was 0·90 cm (SD 0·81), and 17 patients (34%) had a complete radiologic response. VACB identified a pCR in 31 patients (62%). Among these 31 patients, median follow-up was 38.4 months (IQR: 22.4-49·5) the 3-year IBTR rate was 0% (primary endpoint) and 3-year DFS and OS rates were 100%. Two patients were CTC-positive at baseline, 2 were positive at 6-months, and 1 at 12-months. No patients had CTCs detected at more than one timepoint.

Conclusions

Eliminating breast surgery in highly selected patients with an image-guided VACB–determined pCR following NST shows promising 3-year results and additional time and clinical trials evaluating this approach are indicated.

Clinical trial identification

NCT02945579; 20-1-2017 release date.

Editorial acknowledgement

Legal entity responsible for the study

The University of Texas MD Anderson Cancer Center.

Funding

US National Cancer Institute (National Institutes of Health).

Disclosure

H.M. Kuerer: Financial Interests, Personal, Writing Engagements, Editor: NEJM Group; Financial Interests, Personal, Advisory Board: Merck Inc; Financial Interests, Personal, Invited Speaker: Physician Education Resources Inc; Financial Interests, Personal, Royalties, Textbook Editor: McGraw-Hill Professional, Inc; Financial Interests, Personal, Royalties: Elsevier Publishing, Inc; Financial Interests, Personal, Royalties, Editor: Up-To-Date, Inc; Other, Institutional, Invited Speaker, Breast Committee Leadership: NRG Oncology. G. Rauch: Financial Interests, Institutional, Research Grant: GE Healthcare, Inc. S. Krishnamurthy: Financial Interests, Personal, Advisory Board: AstraZeneca Inc; Financial Interests, Personal, Royalties: Elsevier Publishing, Inc. W. Yang: Financial Interests, Personal, Royalties: Elsevier Publishing, Inc. J.A. Mouabbi: Financial Interests, Personal, Advisory Board: GE Healthcare, Inc, Cardinal Health, Inc. J. Boughey: Financial Interests, Institutional, Research Grant: SymBioSis, Inc. S. Shaitelman: Financial Interests, Institutional, Research Grant: Alpha Tau, Exact Sciences, TAE Life Sciences, Artios Pharmaceuticals. K. Hunt: Financial Interests, Personal, Advisory Board: ArmadaHealth, AstraZeneca; Financial Interests, Institutional, Research Grant: Cairn Surgical, Eli Lilly and Company, Lumicell. M. Mitchell: Financial Interests, Institutional, Research Grant: Artidis. B. Smith: Financial Interests, Institutional, Research Grant: Artidis, Varian Medical Systems; Financial Interests, Personal, Stocks/Shares: Oncora Medical. V. Valero: Financial Interests, Personal, Invited Speaker: Roche. All other authors have declared no conflicts of interest.