Although the EBCTCG adopted AFR (irrespective of LRR or DM) as the primary endpoint for the effect of RT in patients with breast cancer , there are little data regarding AFR in mastectomy without PMRT among patients with pT1-2N0 cancer. We performed an analysis using AFR as another primary endpoint and stratified the risk groups based on three factors proven to be significant in the multivariate analysis: age of ≤ 40 years, T2 tumors, and TN subtype. The 10-year AFR rate of the high-risk groups with two to three adverse factors was 18.1%. There are scarce data with which to directly compare our findings.