Population-based risk assessment of second primary cancers following a first head and neck cancer: patterns of association and difficulties of its analysis

The diagnosis of a second primary cancer (SPC) is a major concern in the follow-up of survivors of a primary head and neck cancer (HNC), but the anatomic subsites in the head and neck area are close, making it difficult to distinguish a SPC of a recurrence and therefore register it correctly. We performed a retrospective cohort study using data from two population-based cancer registries in Catalonia, Spain: the Tarragona Cancer Registry and...