The cause of the increased colon cancer mortality rate in Newfoundland & Labrador: a study comparing survival in Newfoundland & Labrador and Ontario population-based cohorts

Background: Colorectal cancer (CRC) is the second leading cause of cancer-related death among Canadian men and women. Newfoundland and Labrador (NL) has the highest CRC mortality rate in the country. To determine whether this resulted from increased CRC incidence, later stage or more adverse prognostic factors at diagnosis, or diminished survival by stage, colon cancer data was compared from NL (n=510) and Ontario (ON) (n=906) cohorts. Methods: Predicted and actual CRC incidence and death rates were obtained. Survival analysis was conducted for stages 1-3 colon cancer patients in the 2 cohorts. Multivariate models included sex, stage and age at diagnosis, microsatellite instability, body mass index, smoking status, and adjuvant treatment. Results: Estimated age-standardized incidence rates in NL were 34% higher in men and 21% higher in women than in ON, comparatively. Actual NL incidence rates were 55% and 53% higher in men and women than estimated. NL cases had improved survival compared to ON at stage 2 (p=.041), otherwise survival by stage was similar. Other adverse predictors of survival were similar between provinces. Conclusion: NL’s high CRC mortality rate can be attributed to increased incidence and not to adverse prognostic indicators or worse survival. This data supports the need for improved CRC screening strategies