PATTERNS OF INITIAL MANAGEMENT OF NODE-NEGATIVE BREAST-CANCER IN 2 CANADIAN PROVINCES

Objective: To describe the patterns of initial management of node-nega tive breast cancer in Ontario and British Columbia and to compare the characteristics of the patients and tumours and of the physicians and hospitals involved in management. Design: Retrospective, population-ba sed, cohort study. Participants: All 942 newly diagnosed cases of node -negative breast cancer in 1991 in British Columbia and a random sampl e of 938 newly diagnosed cases in Ontario in the same year. Outcome me asures: Number and proportion of patients with newly diagnosed node-ne gative breast cancer who received breast-conserving surgery(BCS) or ma stectomy and who received radiation therapy after BCS. Results: BCS wa s used in 413 cases (43.8%) in British Columbia and in 634 cases (67.6 %) in Ontario (p < 0.001). After BCS, radiation therapy was received b y 378 patients (91.5% of those who had undergone BCS) in British Colum bia and 479 patients (75.6% of those who had undergone BCS) in Ontario (p < 0.001). In both provinces, lower patient age, smaller tumour siz e, a noncentral unifocal tumour, absence of extensive ductal carcinoma in situ and initial surgery by a surgeon with an academic affiliation were associated with greater use of BCS. Lower patient age and larger tumour size were associated with greater use of radiation therapy aft er BCS in both provinces. Conclusion: Patient, tumour and physician fa ctors are associated with the choice of initial management of breast c ancer in these two Canadian provinces. However, the differences in man agement between the two provinces are only partly explained by these f actors. Other possible explanations, such as the presence of provincia l guidelines, differences in the organization of the health care syste m or differences in patient preference, require further research.