Impact of postmastectomy radiotherapy on locoregional recurrence and survival in patients with ypN0 breast cancer after neoadjuvant chemotherapy: A comprehensive meta-analysis and systematic review.

Background: The necessity of postmastectomy radiotherapy (PMRT) following neoadjuvant chemotherapy (NAC) in patients with ypN0 breast cancer remains a controversial clinical issue. To elucidate this issue, the present study performed a systematic review and meta-analysis, focusing on studies of clinically lymph node-negative patients exhibiting a favorable pathologic response to NAC.

Materials and methods: After a comprehensive literature search of PubMed and major oncology congress abstracts, 16 studies that met the inclusion criteria were included. A fixed or random effects model was used to assess the impact of PMRT on the local recurrence rate (LRR) and survival outcomes, where appropriate.

Results: The pooled data from ten studies indicated that PMRT significantly reduced the LRR in patients with ypN0 breast cancer (risk ratio [RR], 0.52; 95% confidence interval [CI], 0.41-0.67, P < 0.00001). Moreover, a marginal increase in the overall survival (OS) rates was observed in nine studies (RR, 1.01; 95% CI, 1.00-1.02, P = 0.006), whereas no significant effect on disease-free survival (DFS) was found in six studies (RR, 1.01; 95% CI, 0.95-1.08, P = 0.72).

Conclusions: Our findings suggest that PMRT is associated with reduced LRR and slightly improved OS in patients with ypN0 breast cancer. However, prospective studies are needed to provide more evidence and inform clinical decision-making.