How do registries estimate cancer incidence and survival at the population level?

• A. Complete case ascertainment, accurate coding, and follow-up for vital status; survival uses actuarial or relative survival methods.
• B. Random sampling of hospitals with no follow-up.
• C. Survival estimated from death certificates only.
• D. Patient surveys of survivors.

Answer: (A)

Population-based cancer surveillance relies on finding every new cancer case within a defined population and tracking what happens to those individuals over time. Complete case ascertainment uses multiple, overlapping data sources (such as hospitals, pathology labs, imaging reports, and death records) to capture all incident cancers. Accurate coding ensures each case is classified consistently by site, histology, and other relevant attributes, using standardized systems so counts are reliable and comparable over time and places. Following patients to determine vital status provides the timing data needed to measure survival, and survival analyses can then account for people who are still living or lost to follow-up. Actuarial (life-table) methods handle varying follow-up and censoring, while relative survival compares observed survival to what would be expected in the general population, helping isolate cancer effects on survival. This combination yields valid population-level estimates of both incidence and survival.