The Impact of Geographic Variations in Treatment on Outcomes in Ovarian Cancer

Objective: There are significant regional differences in survival outcomes across British Columbia among women with ovarian cancer. The age-adjusted hazard ratio for mortality is 1.27 (95% confidence interval, 1.08-1.49) in 1 health authority region compared to the provincial mean. The objective of this study was to look at variations in the treatment of epithelial ovarian cancer among the 5 health authority regions in the province of British Columbia and determine their effect on survival. Methods and Materials: This was a population-based retrospective cohort study of all incident cases of epithelial ovarian cancer diagnosed in British Columbia from 2005 to 2008. Health authority regions were compared with the chi(2) test for demographic and disease characteristics, as well as treatment practices including assessment by a gynecologic oncologist, rate of optimal debulking, and proportion receiving platinum-based combination chemotherapy. Multivariable Cox regression analysis evaluated the effect of covariates on survival. Results: There were 854 evaluable patients. Across health authority regions, there were significant differences in disease characteristics, including the proportion with serous histotype (44.0%-60.7%, P = 0.043) and stage IIIC/IV disease (50.3%-69.4%, P = 0.0048). There were also significant differences in treatment, including the proportion of patients assessed by a gynecologic oncologist (56.8%-79.4%, P = 0.0003), rate of suboptimal debulking, (21.4%-60.2%, P = 0.0036), and the proportion receiving combination chemotherapy, (61.5%-81.9%, P < 0.0001). Cox regression model revealed that stage, grade, optimal debulking, and combination chemotherapy were significantly associated with survival. The health authority region with the highest mortality had the lowest rate of optimal debulking and combination chemotherapy. Conclusions: Differences in survival rates for ovarian cancer across British Columbia can be attributed to variations in disease characteristics and treatment, particularly rates of optimal debulking and combination chemotherapy.