Adjuvant radiotherapy for early breast cancer: patterns of practice in Ontario.

OBJECTIVE: To determine the number of different radiation schedules used in Ontario to treat women with node-negative breast cancer after lumpectomy and axillary dissection. DESIGN: Retrospective survey. SETTING: Princess Margaret Hospital, Toronto, and regional centres of the Ontario Cancer Treatment and Research Foundation (in Hamilton, London, Ottawa, Windsor and Thunder Bay). PATIENTS: A total of 551 of 1624 consecutive patients with node-negative breast cancer having undergone lumpectomy and axillary dissection who were eligible but did not participate in the Ontario Clinical Oncology Group randomized clinical trial and who received adjuvant breast irradiation between April 1984 and February 1989. OUTCOME MEASURES: Schedules of radiotherapy received. RESULTS: Forty-eight different radiotherapy schedules were identified. Total doses ranged from 4000 to 6600 cGy and the number of fractions from 15 to 30. Several different schedules were preferred: 322 patients (58.5%) received 4000 cGy in 15 or 16 fractions to the whole breast over 3 weeks plus a local boost of 1250 cGy to the primary site in 5 fractions over 1 week; 66 patients (12.0%) received 4000 cGy in 15 or 16 fractions over 3 weeks to the whole breast plus a local boost of 1000 cGy to the primary site in 4 or 5 fractions over 1 week; and 63 patients (11.5%) received 5000 cGy in 25 fractions to the whole breast in 5 weeks, without a boost. CONCLUSIONS: The practice of adjuvant radiotherapy for early breast cancer in Ontario varies. The optimal radiation regimen for patients after lumpectomy should be determined through randomized clinical trials.