Oncologic and cosmetic outcomes of oncoplastic breast-conserving surgery after neoadjuvant systemic therapy: systematic review and meta-analysis

Purpose: Oncoplastic breast-conserving surgery (OBCS) prevents compromise of breast aesthetics following large breast cancer excisions. This systematic review was conducted to investigate the outcomes (oncologic, surgical, cosmetic) of OBCS versus standard breast-conserving surgery (SBCS) and mastectomy post-neo-adjuvant systemic therapy.

Methods: Ovid, Web of Science, Cochrane, ClinicalTrials.gov databases were searched up to 24/08/2024. English language peer-reviewed RCTs or observational/cohort studies with ≥ 18-year-old women treated for breast cancer with neoadjuvant chemotherapy (NACT) and/or hormonal therapy comparing OBCS to SBCS and/or mastectomy were included. Of 6794 articles, 32 underwent full-text assessment and eleven met the inclusion criteria. The review was conducted using PRISMA guidelines. Two reviewers independently extracted data and assessed risk of bias (Newcastle-Ottowa Scale). Meta-analysis using a random-effects model were performed where data allowed.

Results: Eleven cohort studies (n = 4594) included OBCS (n = 912), SBCS (n = 1122) and mastectomy (n = 2560) after NACT. Post-NACT tumour size was 20(9-44) mm, 13(0-23)mm [SMD 0.62, 95%CI(-0.24,1.48), p = 0.16] and 20(10-31)mm [SMD 0.05, 95%CI(-0.53,0.63), p = 0.86] in the OBCS, SBCS and mastectomy groups respectively. The margin re-excision rate was significantly lower in OBCS than in SBCS [2.9%(0-11.1%) vs. 6.1%(0-18.5%); OR 0.35, 95%CI(0.15,0.80), p = 0.01]. All other oncologic outcomes, including positive margin rate, and overall survival, were not statistically different between the groups. Cosmetic outcomes and patient-reported outcome measures were marginally in favour of OBCS [OBCS 50-66% vs SBCS 37.6-55% very satisfied].

Conclusion: OBCS after NACT appears oncologically safe and a potential alternative in patients with partial or poor tumour response to NACT. Further studies are required, directly comparing well-matched OBCS with SBCS and mastectomy patients after NACT.