Prognostic significance of local recurrence in breast cancer after postmastectomy radiotherapy

Abstract

Purpose: We have retrospectively analyzed the impact of local recurrence in patients with adjuvant radiation therapy after mastectomy for breast cancer.

Patients and methods: From January 1985 through December 1993, 959 patients were irradiated after mastectomy for breast cancer. The age ranged from 34 to 79 years, the median follow-up was 3.1 years (range: 0.3-12.2 years). 368 (38%) were pre- and 591 (62%) postmenopausal. 35% had T3-4 tumors, 62% had axillary lymph node involvement, and 66% received additional systemic hormonal and/or cytotoxic therapy. Postmastectomy radiotherapy was administered in case of positive axillary nodes and in high-risk pN0-patients. The chest wall and lymphatics (axilla, parasternal and supraclavicular nodes) were irradiated with an anterior photon field with 50 Gy and the chest wall with an electron field with 44 Gy in 2-Gy fractions.

Results: The overall survival was 70.5% after 5 and 59.8% after 10 years. 53 patients (5.5%) developed a locoregional recurrence 2-96 months after treatment (median 26 months). The local control rate was 92.7% after 5 and 86.4% after 10 years. Axillary lymph node involvement was the most important and (in a multivariate analysis the only) risk factor for local recurrence (p = 0.0001). Patients with local control had a significantly better 10-year distant-disease-free survival and overall survival as compared to patients with local recurrence (44.5% vs 15.4%, p = 0.002 and 62.1% vs 34.8%, p = 0.004). Local recurrence increased the risk of death by a factor of 1.7 and in a Cox regression model, axillary lymph node status, T-category and local recurrence were significant prognostic factors for overall survival. In patients with local recurrence, the initial axillary lymph node status was the most important prognostic factor for survival after local recurrence. The 3-year survival after local relapse was 86% for patients with pN0 status vs 27% in with positive axillary nodes (p = 0.025).

Conclusions: Local recurrence after treatment of breast cancer with mastectomy + radiotherapy +/- systemic therapy is associated with a significantly higher risk of distant metastases and death. In this analysis, local recurrence was a strong and, besides lymph node status and T category, an independent risk factor for survival. Minimizing the risk of local recurrence is therefore an essential goal of a curative treatment concept.