A Tale of Two Time Periods: Ovarian Cancer Trends in Ontario

Abstract

We assessed population-based trends in incidence and survival rates for epithelial ovarian cancer in Ontario in two time periods. Our population-based study cohort included all women with epithelial ovarian cancer treated initially with abdominal surgery in Ontario for January 1996 through December 2001. Incident surgical cases were documented by hospital contact data and the Ontario Cancer Registry. Patient characteristics (age, for example) were obtained from electronic administrative data records. Regression analyses were used to assess the influence of time period on survival while controlling for age, comorbidity, and other factors associated with this outcome. A total of 3825 women met the inclusion criteria. We found that the age-standardized incidence of ovarian cancer remained stable during 1996–2001. A shift to a younger age at diagnosis was found between the two time periods being compared. The univariate analysis revealed a clear difference in death rate, to which age at diagnosis, Charlson comorbidity score, and treatment period contributed. Earlier time period (p < 0.0001), advancing age (p < 0.0001), higher Charlson score (p < 0.0001), and lower income quartile score (p = 0.03) were significantly associated with poorer survival in the univariate analysis. Younger age, lower Charlson score, and more recent time period of diagnosis and treatment (p < 0.0001) were associated with improved survival in the proportional hazards model. We conclude that age-standardized incidence and mortality rates for ovarian cancer in Ontario have remained stable. For women initially treated with surgery, advances in management have led to an improvement in survival.