Clinically Apparent Internal Mammary Nodal Metastasis in Patients With Advanced Breast Cancer: Incidence and Local Control

Purpose To investigate the incidence and local control of internal mammary lymph node metastases (IMN+) in patients with clinical N2 or N3 locally advanced breast cancer. Methods and Materials We retrospectively reviewed the records of 809 breast cancer patients diagnosed with advanced nodal disease (clinical N2–3) who received radiation treatment at our institution from January 2000 December 2006. Patients were considered IMN+ on the basis of imaging studies. Results We identified 112 of 809 patients who presented with IMN+ disease (13.8%) detected on ultrasound, computed tomography (CT), positron emission tomography/CT (PET/CT), and/or magnetic resonance imaging (MRI) studies. All 112 patients with IMN+ disease received anthracycline and taxane-based chemotherapy. Neoadjuvant chemotherapy (NCT) resulted in a complete response (CR) on imaging studies of IMN disease in 72.1% of patients. Excluding 16 patients with progressive disease, 96 patients received adjuvant radiation to the breast or the chest wall and the regional lymphatics including the IMN chain with a median dose of 60 Gy if the internal mammary lymph nodes normalized after chemotherapy and 66 Gy if they did not. The median follow-up of surviving patients was 41 months (8–118 months). For the 96 patients able to complete curative therapy, the actuarial 5-year IMN control rate, locoregional control, overall survival, and disease-free survival were 89%, 80%, 76%, and 56%. Conclusion Over ten percent of patients with advanced nodal disease will have IMN metastases on imaging studies. Multimodality therapy including IMN irradiation achieves excellent rates of control in the IMN region and a DFS of more than 50% after curative treatment.