Role of a 10-Gy boost in the conservative treatment of early breast cancer: Results of a randomized clinical trial in Lyon, France

Purpose: To define the role of a 10-Gy boost to the primary tumor in the conservative treatment of early infiltrating breast carcinoma treated by limited surgery and radiotherapy. Patients and Methods: Between 1936 and 1992, 1,024 women with early breast carcinoma (less than or equal to 3 cm in diameter) were treated by local excision, axillary dissection, and conventional 50-Gy irradiation given in 20 fractions over 5 weeks and then randomly assigned to receive either no further treatment or a boost of 10 Gy by electrons to the tumor bed. The median follow-up time was 3.3 years as of September 1994. The occurrence of telangiectasia was reported, and the patients were asked to evaluate the cosmetic result. Results: At 5 years, 10 patients of 521 who had received the boost (Kaplan-Meier estimate of local relapse rate, 3.6%) and 20 of 503 who had received no further treatment (Kaplan-Meier estimate of local relapse rate, 4.5%) had developed a local recurrence (P = .044). After adjustment for the main prognostic variables, the relative risk was still significantly lower for the boost group (0.3; range, 0.12 to 0.95). The boost group had a higher rate of grade 1 and 2 telangiectasia (12.4% v 5.9%), but no difference was seen between the two treatment arms in the self-assessment score for the cosmetic result. Conclusion: Delivery of a boost of 10 Gy to the tumor bed after 50 Gy to the whole breast following limited surgery significantly reduces the risk of early local recurrence, with no serious deterioration in the cosmetic result. Additional follow-up evaluation will be required to assess the long-term results. (C) 1997 by American Society of Clinical Oncology.