Mood disorder and cancer onset: evidence from a population-based sample of Australian women

OBJECTIVE: The role of mood disorders in cancer onset is unclear. The aim of this study was to investigate the association between mood disorder and incident cancer in a population-based sample of women. METHODS: Data were derived from women aged 28-94 years participating in the Geelong Osteoporosis Study. Mood disorder was identified via Clinical Interview (SCID-I/NP). Cancer data was obtained following linkage with the Victorian Cancer Registry. Demographic and lifestyle factors were self-reported. Nested case-control and retrospective study designs were utilized. RESULTS: In the case-control study (n=807), mood disorder was documented for 18 of the 75 (9.3%) cancer cases and among 288 controls (24.0% vs. 39.3%, p = 0.009). Prior exposure to mood disorder was associated with reduced cancer incidence (OR 0.49, 95%CI 0.28-0.84); this was sustained following adjustment for confounders (OR(adj) 0.52, 95%CI 0.30-0.90). In the retrospective cohort study (n=655), among 154 women with a history of mood disorder at baseline, 13 (8.5%) developed incident cancer during follow-up, whereas among 501 women with no history of mood disorder, 54 (10.8%) developed incident cancer. Exposure to mood disorder was not associated with incident cancer over the follow-up period (HR 0.58, 95%CI 0.31-1.08, p = 0.09). CONCLUSION: Mood disorder was associated with reduced odds of cancer onset. However, this finding was not supported in the retrospective cohort study. Larger studies able to investigate specific cancers and mood disorders as well as underlying mechanisms in both men and women are warranted.