Postoperative irradiation in breast cancer patients with one to three positive axillary lymph nodes : Is there an impact of axillary extranodal tumor extension on locoregional and distant control?

Background and Purpose: To evaluate the impact of extracapsular extension (ECE) on locoregional and distant control in breast cancer patients with one to three positive axillary lymph nodes treated with postoperative irradiation. As shown in literature, ECE is diagnosed in up to 30% of node-positive breast cancer patients. Consequences of ECE and prognosis of these patients are unclear. Patients and Methods: The medical records of 1,142 node-positive females with a carcinoma of the breast, postoperatively irradiated between 1994 and 2003, were retrospectively reviewed. Of the 274 patients presenting with one to three positive axillary lymph nodes, 91 (33.2%) showed ECE. While all patients were irradiated using tangential fields, only eight out of 274 patients received additional nodal irradiation. Results: Patients' mean age was 58.2 years (range, 28-96 years), and the mean observation period 42.9 months (range, 6.6-101 months). In 93.4% of patients, locoregional control was achieved. On multivariate analysis of metastases-free survival, the hazard ratios for ECE and histological grade 3 were 2.71 (95% confidence interval [CI], 1.316-5.581; p = 0.007) and 2.435 (95% CI, 1.008-5.885; p = 0.048), respectively. The 3-year and 5-year metastases-free survival rates for patients with ECE were 78% and 66%, compared to 90% and 87% in patients without ECE (p = 0.0048). Conclusion: Locoregional recurrence remains low in breast cancer patients (one to three positive axillary lymph nodes ± ECE) treated with surgery, adequate axillary dissection, and tangential field irradiation only. However, ECE is significantly linked to a considerable risk for subsequent distant failure.