A Nomogram to Predict the Benefit of Radiation Therapy After Breast-Conserving Surgery in Elderly Patients with Stage I & ER-Negative, or Stage II/III Disease.

Abstract

Radiotherapy (RT) may be omitted for elderly (age >70 years) breast cancer patients with favorable disease [stage I and estrogen receptor (ER)-positive with endocrine therapy]. This study sought to develop a nomogram to predict the survival benefit of RT in elderly patients with stage I & ER-negative or stage II/III (regardless of ER status) disease. We used surveillance, epidemiology and end results data to identify 9,079 patients (age ≥70 years) with stage I & ER-negative or stage II/III (regardless of ER status) disease who received breast-conserving surgery between 1990 and 2005. Cancer-specific survival (CSS) was estimated using Kaplan-Meier analysis. Competing-risk regression was used to determine the effect of predictors on CSS. A nomogram was then developed and validated using bootstrapped technique. With a median follow-up of 83 months, the overall 10- and 15-year CSS were 82.1 and 75.8 %, respectively. RT was significantly associated with improved CSS in the multivariate analysis. A nomogram was developed for the prediction of 10-year CSS and showed a bootstrapped-corrected area under the curve value of 0.679. RT did not deliver any survival benefit to patients with predicted CSS >90 %. In addition, RT significantly increased the 10-year CSS by 3.6 and 10.1 % in patients with predicted CSS from 0.80 to 0.90 and <0.80, respectively. This nomogram is a useful tool to predict the 10-year CSS in patients with stage I and ER-negative or stage II/III (regardless of ER status) disease. The benefit of RT varied among patients with different predicted CSS.