Internal mammary nodes in invasive breast carcinoma: To treat or not to treat?

Abstract

Background and Purpose: According to recent data medial location of early breast cancer was associated with a higher risk of systemic relapse and breast cancer death compared with lateral location. This paper will focus on literature data and will also present own data on the prognostic impact of radiation therapy (RT) to internal mammary nodes (IMNs) in early breast cancer patients with medial hemisphere tumor location. Patients and Methods: Four large recent series of the literature reporting on > 50,000 patients with special focus on the impact of tumor location were evaluated. No systematic RT to IMNs was applied. At the Department of Radiation Oncology, University of Erlangen, Germany, a total of 822 patients (492 with lateral and 330 with medial lesions) with early breast cancer were treated by surgery and postoperative RT with or without chemotherapy (1985-1996). All patients with medial lesions received RT to IMNs by a mixed-beam approach (50% photons, 50% electrons) with a total dose of 50 Gy. In patients with lateral lesions RT was directed to the breast alone (50.4 Gy total dose, boost 12-16 Gy). Results: The magnitude of the negative impact of medial tumor location was relatively similar in all four studies available. According to Zucali et al., the hazard ratio (HR) for distant metastases was 1.29. The HR for breast cancer-specific survival (BCSS) varied between 1.46 (Lohrisch et al.) and 1.31 (Gaffney et al.). 5-year systemic disease-free survival (SDFS) rates were 66.3% and 74.2% for high-risk medial and lateral lesions, respectively (p < 0.005). Corresponding BCSS were 75.7% and 80.8%, respectively (p < 0.03, Lohrisch et al.). For all 822 patients following treatment on IMNs, 5-year overall survival (OS) for lateral lesions and medial lesions was 76.2% and 79.1% (n.s.), and SDFS for lateral and medial tumors 72.6% and 72.9% (n.s.), respectively. No subgroup could be identified in which prognosis of patients with medial tumors was inferior to survival data for patients with lateral lesions. In postmenopausal women, OS was significantly better for patients with medial versus lateral tumors (77.6% vs. 72.7%; p = 0.05); in patients receiving adjuvant chemotherapy SDFS (5 years) was better for those with medial versus lateral tumors (80.5% vs. 67.6%; p = 0.02). Conclusion: Consistent literature data exist indicating a diminished survival in patients with inner versus outer quadrant breast cancer. According to our data, RT with a total dose of 50 Gy to IMNs in breast cancer patients with medial lesions was associated with OS and SDFS rates comparable to patients with lateral tumors.