ABSTRACT
PURPOSE: It is unknown whether irradiation of the internal mammary lymph nodes improves survival in patients with early-stage breast cancer. A possible survival benefit might be offset by radiation-induced heart disease. We assessed the effect of internal mammary node irradiation (IMNI) in patients with early-stage node-positive breast cancer. PATIENTS AND METHODS: In this nationwide, prospective population-based cohort study, we included patients who underwent operation for unilateral early-stage node-positive breast cancer. Patients with right-sided disease were allocated to IMNI, whereas patients with left-sided disease were allocated to no IMNI because of the risk of radiation-induced heart disease. The primary end point was overall survival. Secondary end points were breast cancer mortality and distant recurrence. Analyses were by intention to treat. RESULTS: A total of 3,089 patients were included. Of these, 1,492 patients were allocated to IMNI, whereas 1,597 patients were allocated to no IMNI. With a median of 8.9 years of follow-up time, the 8-year overall survival rates were 75.9% with IMNI versus 72.2% without IMNI. The adjusted hazard ratio (HR) for death was 0.82 (95% CI, 0.72 to 0.94; P = .005). Breast cancer mortality was 20.9% with IMNI versus 23.4% without IMNI (adjusted HR, 0.85; 95% CI, 0.73 to 0.98; P = .03). The risk of distant recurrence at 8 years was 27.4% with IMNI versus 29.7% without IMNI (adjusted HR, 0.89; 95% CI, 0.78 to 1.01; P = .07). The effect of IMNI was more pronounced in patients at high risk of internal mammary node metastasis. Equal numbers in each group died of ischemic heart disease. CONCLUSION: In this naturally allocated, population-based cohort study, IMNI increased overall survival in patients with early-stage node-positive breast cancer.
Subject(s)
Breast Neoplasms/radiotherapy , Lymph Nodes/radiation effects , Adult , Breast Neoplasms/mortality , Breast Neoplasms/pathology , Breast Neoplasms/surgery , Cohort Studies , Denmark/epidemiology , Female , Humans , Lymph Nodes/pathology , Lymphatic Metastasis , Middle Aged , Prospective Studies , Radiotherapy, AdjuvantABSTRACT
The indication for adjuvant postmastectomy radiotherapy (PMRT) in breast cancer patients with small tumors and 1-3 macrometastases in the axilla remains a controversial issue, despite the recommendation that PMRT should be applied in these patients in the most recent overview by the Early Breast Cancer Trialists' Collaborative Group. In this report, we discuss the available data on the benefit from PMRT in patients diagnosed with N1 breast cancer. Based on this, we recommend adjuvant PMRT to the chest wall and regional lymph nodes in patients diagnosed with early node-positive breast cancer.
