Effect of Radiotherapy after Mastectomy and Axillary Surgery on 10-Year Recurrence and 20-Year Breast Cancer Mortality: Meta-Analysis of Individual Patient Data for 8135 Women in 22 Randomised Trials

Postmastectomy radiotherapy is usually recommended for women with high-recurrence-risk breast cancer, with guidelines suggesting that women with disease greater than 5 cm, locally advanced (T3 or T4), with involved margins or with nodal disease should be offered treatment. Postmastectomy radiotherapy has been shown in previous meta-analyses to reduce the risks of both recurrence and breast cancer mortality in all women with node-positive disease considered together. However, the benefit in women with only one to three positive lymph nodes has been an area of uncertainty. The benefit must be weighed against the risks, with evidence of negative quality-of-life impacts 1 and long-term adverse events. This study aimed to assess the effect of postmastectomy radiotherapy in women stratified by nodal burden, after mastectomy and axillary surgery.