Local control of operable breast cancer after radiotherapy alone.

221 patients with operable breast carcinoma stage Tis, T1, T2, T3, N0N1 were treated with radiotherapy alone without tumorectomy. The mean follow-up time was 15.5 years (range 5-22). The annual risk for local recurrence was 3% during the first 5 years and 1% during the following 10 years, resulting in an actuarial local control rate of 75.4% after 15 years. The risk for local recurrence was assessed in multivariate analysis and was significantly related to the size of the tumour measured on mammography (P = 0.0002), the radiation dose administered (P = 0.0018), the length of the split-course intervals being longer than 75 days (P = 0.001) and age (P = 0.019). Dose was related to response over a wide range as a function of tumour volume. All 18 patients with minimal tumour load (T0 and Paget's disease) treated with doses above 55 Gy in 6 weeks achieved local control. 5-year local control rates ranged from 40 to 100% for T1 carcinomas treated with 45-110 Gy, and from 0 to 95.3% for T2 carcinomas at the same dose. For T3 carcinomas local control varied between 50 and 83% at 60-110 Gy. The risk for local failure increased by 8% per cm tumour diameter. With exclusive radiotherapy, the doses needed to provide local control rates similar to those obtained after tumorectomy and irradiation are 10 Gy higher for T1 (95% 5 year control) and 35 Gy higher for T2 (90% 5 year control).