Depression and the risk of cancer: a 15-year follow-up study of the GAZEL cohort.

Depression has long been hypothesized to be associated with cancer incidence. However, there is evidence for a positive publication bias in this field. In the present study, we examined the association between various measures of depression and cancer incidence at several sites. A total of 14,203 members of the French GAZEL (Gaz et Electricité) cohort (10,506 men, 3,697 women) were followed up for diagnoses of primary cancers from January 1, 1994, to December 31, 2009. All medically certified sickness absences for depression recorded between January 1, 1990, and December 31, 1993, were compiled. Depressive symptoms were self-reported in 1993, 1996, and 1999 with the Center for Epidemiologic Studies Depression Scale. During a mean follow-up period of 15.2 years, 1,119 participants received a cancer diagnosis, excluding nonmelanoma skin cancer and in situ neoplasms. Considering 6 cancer sites (prostate, breast, colorectal, smoking-related, lymphoid and hematopoietic tissues, other sites) and 4 measures of depression, we found 1 positive association and 1 negative association. Overall, there was no compelling evidence for an association between depression and cancer incidence. Such null results should be considered when addressing concerns of cancer patients and their relatives about the role of depression in cancer onset.