Is it beneficial for patients with pT1-2N1M0 breast cancer to receive postmastectomy radiotherapy? An analysis based on RecurIndex assay

The benefit of postmastectomy radiotherapy (PMRT) for pT1-2N1M0 breast cancer patients currently remains controversial. This study was conducted to investigate whether pT1-2N1M0 breast cancer patients could benefit from PMRT based on RecurIndex assay. The clinical data of 213 pT1-2N1M0 breast cancer patients were retrospectively analyzed. Through RecurIndex assay, 81 cases were assessed as the low risk, and 132 as the high risk. Compared to low-risk patients, high-risk patients especially those not receiving PMRT had a significantly increased risk of recurrence and metastasis, and worse 7-year local-regional recurrence-free interval (LRFI), distance recurrence-free interval (DRFI) and recurrence-free survival (RFS) rates. PMRT-based subgroup analysis indicated no significant differences between the low-risk patients with and without PMRT in 7-year LRFI, DRFI, RFS and overall survival (OS) rates, but apparent differences were all shown between the high-risk patients with and without PMRT in 7-year LRFI, DRFI, RFS and OS rates. Overall, for pT1-2N1M0 breast cancer patients at low risk of recurrence and metastasis stratified by RecurIndex assay, there may be a phenomenon of no PMRT benefits, while for those at high risk, use of PMRT may produce survival benefits.