Aims: To evaluate the oncological outcomes of omitting breast surgery in breast cancer patients achieving pathological complete response (pCR) after neoadjuvant systemic treatment (NST), and to assess the influence of response assessment methods on treatment safety.
Materials & Methods: A systematic review and meta-analysis were conducted in accordance with the PRISMA 2020 guidelines. PubMed/MEDLINE, Scopus, Web of Science, Embase, Cochrane CENTRAL, and ScienceDirect were searched without date restrictions. Studies evaluating oncological outcomes in breast cancer patients with complete response after NST who did not undergo definitive breast surgery were included. RRs with 95% CIs were calculated using a Mantel–Haenszel random-effects model. Heterogeneity in response assessment methods was considered a priori.
Findings: Eight studies published 1986 - 2021 were included, comprising comparative cohorts, prospective phase II trials, a database study, and a case series. Comparative meta-analysis demonstrated no significant differences at 5 years between surgery omission and surgery groups for disease-free survival (RR 0.92, 95% CI 0.78–1.08), overall survival (RR 1.08, 95% CI 0.97–1.21), or metastasis-free survival (RR 1.08, 95% CI 0.97–1.20), with low heterogeneity (I² = 0%). Locoregional recurrence showed a non-significant trend favouring surgery. Contemporary studies using vacuum-assisted biopsy (VAB)-confirmed pCR reported 0% ipsilateral breast tumour recurrence, whereas older studies relying on clinical or imaging criteria reported higher recurrence rates.
Conclusions: Omission of breast surgery after NST may be feasible in highly selected patients when pCR is reliably confirmed, particularly using VAB-guided protocols. Nevertheless, this approach remains investigational pending results from ongoing randomized trials.