The role of postmastectomy radiation in patients with ypN0 breast cancer after neoadjuvant chemotherapy: a meta-analysis

BACKGROUND: It has been demonstrated that postmastectomy radiation therapy (PMRT) was beneficial for breast cancer patients who are axillary lymph node-positive. However, the effectiveness of radiotherapy in pathological negative nodes (ypN0) after neoadjuvant chemotherapy (NAC) remains open to considerable debate. Here, we aim to evaluate whether PMRT improves loco-regional control and survival for such patients. METHODS: The literature from January 2004 to June 2019 was searched. The effects of PMRT on local-regional recurrence (LRR) and survival was evaluated in a meta-analysis. Pooled relative risk (RR) values with 95% confidence intervals (CIs) were computed using random and fixed-effect model. Subgroup and heterogeneity analyses were also conducted. RESULTS: Twelve studies that included 17,747 patients met the inclusion criteria. Pooled results showed that PMRT was associated with reduced LRR (RR, 0.38; 95% CI, 0.19–0.77, P = 0.007), particularly in patients with stage III breast cancer (RR, 0.16; 95% CI, 0.07–0.37, P < 0.001). However, no significant difference in disease-free survival were observed with the addition of PMRT for ypN0 patients (RR, 0.70; 95% CI, 0.21–2.27, P = 0.55). Also, there was no statistically significant association between radiotherapy with overall survival (RR, 0.81; 95% CI, 0.64–1.04, P = 0.10). CONCLUSIONS: Our meta-analysis indicated that PMRT might reduce local-regional recurrence for ypN0 patients after NAC, but lack of benefit for survival outcomes. Prospective randomized clinical trial data will be needed to confirm our results. SUPPLEMENTARY INFORMATION: The online version contains supplementary material available at 10.1186/s12885-021-08423-1.