The role of irradiation of the internal mammary lymph nodes in high-risk stage II to IIIA breast cancer patients after high-dose chemotherapy: a prospective sequential nonrandomized study

Abstract

Purpose: This phase II single-institution prospective, nonrandomized trial investigates high-dose adjuvant chemotherapy and locoregional radiotherapy in patients with breast cancer. We compared the outcome of patients in this study treated with radiotherapy fields including the internal mammary nodes (IMN) to a group of patients who did not receive IMN irradiation.

Patients and methods: 100 patients with high-risk stage II-III breast cancer received doxorubicin-based adjuvant chemotherapy followed by high-dose chemotherapy, stem-cell support, and locoregional radiotherapy. The radiotherapy included electron-beam irradiation to the IMN. For 20 months during the study, no electron-beam facility was available and we were unable to deliver the IMN irradiation as planned to 33 patients. The remaining 67 patients (32 treated before and 35 treated after this period) received IMN irradiation. Patients with receptor-positive tumors received tamoxifen for 5 years.

Results: At a median follow-up of 77 months for all of the patients, disease-free survival (DFS) was significantly prolonged in patients receiving IMN radiation compared to those without IMN radiation (73% v 52%; P =.02). A trend was seen for overall survival (OS; 78% v 64%; P =.08). Cox regression multivariate analysis found IMN radiotherapy to be significant both for DFS and OS. Estrogen receptor positivity was also significant for DFS. There was no treatment related mortality.

Conclusion: In patients with high-risk stage II to III breast cancer, the inclusion of the IMN in the radiotherapy field was associated with a statistically significant increase in DFS and a borderline increase in OS.