A meta-analysis on depression and subsequent cancer risk.
BACKGROUND
The authors tested the hypothesis that depression is a possible factor influencing the course of cancer by reviewing prospective epidemiological studies and calculating summary relative risks.


METHODS
Studies were identified by computerized searches of Medline, Embase and PsycINFO. as well as manual searches of reference lists of selected publications. Inclusion criteria were cohort design, population-based sample, structured measurement of depression and outcome of cancer known for depressed and non-depressed subjects


RESULTS
Thirteen eligible studies were identified. Based on eight studies with complete crude data on overall cancer, our summary relative risk (95% confidence interval) was 1.19 (1.06-1.32). After adjustment for confounders we pooled a summary relative risk of 1.12 (0.99-1.26).No significant association was found between depression and subsequent breast cancer risk, based on seven heterogeneous studies, with or without adjustment for possible confounders. Subgroup analysis of studies with a follow-up of ten years or more, however, resulted in a statistically significant summary relative risk of 2.50 (1.06-5.91).No significant associations were found for lung, colon or prostate cancer.


CONCLUSIONS
This review suggests a tendency towards a small and marginally significant association between depression and subsequent overall cancer risk and towards a stronger increase of breast cancer risk emerging many years after a previous depression.
Maastricht University, Department of General Practice, School of Public Health and Primary Care: CAPHRI, Maastricht, the Netherlands. Marjan.vandenakker@hag.unimaas.nl.
Marjolein Ej
ME
Oerlemans
Marjan
M
van den Akker
Agnes G
AG
Schuurman
Eliane
E
Kellen
Frank
F
Buntinx