TEMPORAL TRENDS IN BREAST-CANCER SURGERY IN ONTARIO - CAN ONE RANDOMIZED TRIAL MAKE A DIFFERENCE

Objective: To assess the effect of a single randomized clinical trial, the National Surgical Adjuvant Breast Project (NSABP) B-06, on the su rgical management of breast cancer in women. Design: Retrospective coh ort study. Setting: All hospitals in Ontario. Patients: A consecutive sample of 37 447 women with breast cancer newly diagnosed from Jan. 1, 1980, to Dec. 31, 1989, linked to a surgical procedure record in the Ontario Cancer Registry. Main outcome measure: The most invasive surgi cal procedure used within 90 days of diagnosis. Results: Unilateral br east-ablative surgery (BAS) was performed in 57.3% of the women and br east-conserving surgery (BCS) in 31.6%. The annual rate of BAS decline d from 77.5% in 1980 to 44.2% in 1989 and the rate of BCS rose from 12 .5% in 1980 to 43.5% in 1989. The decline was linear from 1980 to 1984 and then accelerated significantly in 1985 (p < 0.0001), after the re sults of the NSABP B-06 trial were published. Conclusion: One randomiz ed clinical trial can have an immediate and profound effect on medical practice.