Is radiation indicated for young women with early stage, node-negative breast cancer after mastectomy? A multi-institution, retrospective review.

The role of post-mastectomy radiation for women with node negative, early stage disease is not well-defined. The purpose of this study is to more clearly define a subset of women who are ≤40 years of age with T1-T2, node negative breast cancer who may benefit from post-mastectomy radiation. Using tumor registries at two institutions, we identified 219 women ≤40 years of age with T1-T2, node negative breast cancer treated with mastectomy. Of these 219 patients, 38 received post-mastectomy radiation and 181 did not. Kaplan-Meier methods and cox proportional-hazards regression models were employed for statistical analysis. There were no locoregional failures in the women receiving post mastectomy radiation, which lead to a nonsignificant increase in freedom from locoregional recurrence (P=.08). For women not receiving post-mastectomy radiation, freedom from locoregional recurrence was 94.7% and 89.7% at 5- and 10-years. Lymphovascular space invasion (LVSI) was the only factor predictive of locoregional recurrence. For women without LVSI, freedom from locoregional recurrence was 96.0% and 93.3% at 5- and 10-years respectively. For women with LVSI who did not receive post mastectomy radiation, freedom from locoregional recurrence was 89.1% at 5-years. There were no failures in the women with LVSI who received post mastectomy radiation. For women ≤40 years of age with T1-2, node negative breast cancer treated with mastectomy and no post-mastectomy radiation, locoregional control is excellent in the absence of LVSI, regardless of other risk factors. In the presence of LVSI (regardless of other risk factors), the risk of locoregional recurrence is high and appears to be decreased with post-mastectomy radiation.