Ascertaining cancer survivors in Ontario using the Ontario Cancer Registry and administrative data.

34Background: The number of cancer survivors in Ontario has grown rapidly due to increasing incidence and advances in screening, diagnostic technologies and treatment. However, there is a lack of information to plan, monitor and improve follow-up care. Using the Ontario Cancer Registry (OCR) and health services administrative data, we developed a cohort of cancer survivors from which we could determine demographic characteristics, where follow-up care was received, and concordance with guideline-recommended surveillance testing. Methods: Individuals were included in the cumulative survivor cohort if they had at least one diagnosed incident malignant cancer from 1964 to 2017 in the OCR. Patients were considered survivors upon completion of treatment (surgery, chemotherapy, radiation therapy). Treatment was ascertained from clinical and administrative data using a data-driven approach combined with clinical expert input. In the absence of recurrence data, a treatment-based proxy was developed. Stage IV and ...