Variation in breast cancer surgery in Ontario.

Abstract

OBJECTIVES: To analyse the extent of variation by county and hospital in the use of breast-conserving surgery in the initial management of breast cancer and to assess some factors that might explain the observed variation. DESIGN: Population-based retrospective cohort study. SETTING: Ontario. PATIENTS: All women with breast cancer newly diagnosed from Jan. 1, 1989, to Dec. 31, 1991. MAIN OUTCOME MEASURE: Proportion of women undergoing unilateral breast cancer surgery who had breast-conserving surgery in each hospital and county. RESULTS: Of the 14,570 women with newly diagnosed breast cancer 12,815 (88.0%) underwent unilateral breast cancer surgery. The mean proportion of breast-conserving procedures by county was 52% and ranged from 11% to 84%. The proportion of breast-conserving procedures in individual hospitals with one or more cases of breast cancer per month ranged from 6% to 84%. The variations in the rates between hospitals was greater than that expected by chance alone (p < 0.0001). CONCLUSIONS: There was marked variation at the hospital and county level in the use of breast-conserving surgery in the initial management of breast cancer. This variation was strongly associated with the hospital where the surgery was performed.