Survival benefit of post-mastectomy radiotherapy in breast carcinoma patients with T1-2 tumor and 1-3 axillary lymph node(s) metastasis.

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=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=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=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=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.