Identifying incident cancer cases in routinely collected hospital data: a retrospective validation study.

The more recent hospital diagnosis data were valid for identifying incident cases for the six cancer types, with sensitivities 81-94% and PPVs 86-96%. However, 2-10% of cases were identified > 3 months after the registry's diagnosis date and detailed clinical cancer information was unavailable. The level of identification was generally higher for cases aged < 80 years, those with known disease stage and cases living in higher socioeconomic areas. The inclusion of death records increased sensitivity for some cancer types, but requires caution due to potential false-positive cases. This study validates the use of hospital diagnosis records for identifying incident cancer cases.