Objective: To investigate the role of post-mastectomy radiotherapy in breast carcinoma patients with a tumor size of 5 cm or smaller (T1-2) and 1 -3 axillary lymph node(s) metastasis (N1). Methods: We retrospectively reviewed the file records of 575 patients receiving radiotherapy (452 patients) and not receiving radiotherapy (123 patients). Results: In the whole series, locoregional recurrence-free survival was significantly better in patients receiving radiotherapy compared with patients not receiving radiotherapy (P , 0.001); in the multivariate Cox analysis, radiotherapy had an independent prognostic value (P , 0.001). In patients with a tumor size of 2 cm or less (T1), locoregional recurrence-free survival was significantly better in patients receiving radiotherapy compared with those not receiving radiotherapy (P ¼ 0.016). In the patient subgroup with a T1 tumor and a lymph node ratio (the ratio of the number of metastatic lymph nodes to the number of removed lymph nodes) of 0.25 or less, there was no significant difference between the patients receiving and not receiving radiotherapy in terms of locoregional recurrence-free survival (P ¼ 0.071). In patients with a tumor size of 2.1 -5 cm (T2), locoregional recurrence-free survival was significantly better for patients who received radiotherapy compared with those who did not (P ¼ 0.001). In patients with a T2 tumor and a lymph node ratio of 0.08, there was no significant difference in locoregional recurrence-free survival between the patients receiving and not receiving radiotherapy (P ¼ 0.645). Conclusions: Post-mastectomy radiotherapy is beneficial in reducing the locoregional recurrence risk in T1N1 breast carcinoma patients with a lymph node ratio of .0.25 and in T2N1 breast carcinoma patients with a lymph node ratio of .0.08. In patients with a lymph node ratio equal to or less than these ratios, post-mastectomy radiotherapy could be omitted to avoid radiotherapy-related risks.

LC and OS rates are high in the low-risk group of patients; however, current adjuvant therapies did not improve the outcomes. Age over 60 years and the presence of LVI have negative effects on outcomes in this group of patients.

Survival is worse in patients older than 60 years, had late treatment beginning, advanced stage and D0 dissection.

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