Abstract P4-16-05: Benefit from Postoperative Radiotherapy for N1 Breast Cancer

Abstract

Abstract Purpose: To evaluate the outcomes for patients with Stage II breast cancer and one to three positive lymph nodes after mastectomy who were treated with observation or adjuvant radiotherapy to the chest wall (CW) and regional lymphatics; and to identify a group of patients who benefit from postmastectomy radiotherapy (PMRT). Methods and Materials: The subjects were 716 patients diagnosed between 1990 and 2007 with Stage II breast cancer (one to three positive lymph nodes) treated with mastectomy at the Koo Foundation Sun Yat-Sen Cancer Center. 283 patients had undergone PMRT to the CW and regional lymphatics according to in-house treatment guideline or physician decision. Since 2003, we recommend PMRT for patients who had 2 or more risk factors; age less than 40 y/o, T2 disease, GrII/GrIII, prominent lymphovascular invasion (LVI), presence of extracapsular spreading (ECS), and negative Estrogen Receptor (ER(−)). Survival was analyzed by the Kaplan—Meier method. The survival free of isolated locoregional disease(LRR), metastasis free survival(MFS), disease free survival(DFS), and overall survival(OS) were analyzed according to the delivery of radiotherapy or not. Results: The median follow-up was 80 months. LRR, MFS, DFS and OS were significantly improved by PMRT. The 5- and 10-year LRR rate without PMRT was 89.9% and 81.6%, respectively and, with PMRT was 97.7% and 97.0% respectively (p <0.0001). The 5- and 10-year MFS rate without PMRT was 84.4% and 76.5%, respectively, and, with PMRT, was 90.8% and 87.2% respectively (p = 0.0153). The 5- and 10-year DFS rate without PMRT was 80.8% and 69.8%, respectively, and, with PMRT, was 89.6% and 86.1% respectively (p = 0.001). The 5- and 10-year OS rate without PMRT was 89.1% and 77.3%, respectively, and, with PMRT, was 94.6% and 86.2% respectively (p = 0.0039). 239 patients had less than 2 risk factors, their LRR, MFS and DFS did not benefit from PMRT. Conclusion: Our data suggest that adjuvant PMRT improve LRR, MFS, DFS and OS for stage II breast cancer with one to three positive lymph nodes who had 2 or more risk factors (Age less than 40 y/o, T2, GrII/GrIII, LVI, ECS, ER(−)). Citation Information: Cancer Res 2012;72(24 Suppl):Abstract nr P4-16-05.