Pooling prospective studies to investigate the etiology of second cancers

A partir des données agrégées issues de cinq études prospectives incluant plus de 800 000 participants, cette étude américaine analyse la faisabilité de diverses méthodes d'estimation des facteurs de risque de seconds cancers

Résumé en anglais

Background: With over 13 million cancer survivors in the United States today, second cancers are of rapidly growing importance. However, data on non-treatment risk factors for second cancers are sparse. We explored the feasibility of pooling data from cohort studies of cancer incidence to investigate second cancer etiology.

Methods: We combined data from five prospective studies including more than 800,000 individuals. We compared study designs and populations; evaluated availability of and ability to harmonize risk factor data; compared incidence and survival for common first primary malignancies and incidence of second primary malignancies; and estimated sample size requirements.

Results: Overall, 96,513 incident, first primary malignancies were diagnosed during 1985-2009. Incidence rates and survival following the first primary varied among the cohorts, but most of the heterogeneity could be explained by characteristics of the study populations (age, sex, smoking, and screening rates). 7,890 second primary cancers (excluding original primary site) were identified, yielding sufficient statistical power (≥80%) for detecting modest associations with risk of all second cancers among survivors of common first primary malignancies (e.g., colorectal cancer); however, there were insufficient events for studying survivors of rarer cancers or identifying risk factors for specific second cancers.

Conclusion: Pooling data from cohort studies to investigate non-treatment risk factors for second primary cancers appears feasible but there are important methodological issues - some of which are barriers to specific research questions - that require special attention. Impact: Increased understanding of non-treatment risk factors for second cancers will provide valuable prevention and surveillance information.