Increased risk of cancer subsequent to severe depression-A nationwide population-based study

Background: Empirical findings on the association between a history of depression and subsequent cancer incidence are mixed and inconclusive. A link between depression and cancer would gain greater credence if it can be sustained across cultures. This nationwide, population-based study aimed to prospectively examine the relationship between a psychiatric diagnosis of depression in an inpatient setting and the risk of developing cancer in the following five years in Taiwan. Method: This study used data from the Taiwan National Health Insurance Research Database. A total of 778 patients hospitalized for depression from 1998 to 2003 were recruited, together with 3890 matched non-depressive enrollees as a comparison cohort. Each patient was tracked five years to identify the occurrence of any type of cancer. The Cox proportional hazards models were carried out to compute the risk of cancer between study and comparison cohorts, following adjustment for residence and socio-demographic characteristics. Results: We found that during a five-year follow-up, 61 severely depressed patients (7.8%) and 212 patients in the non-depressed comparison cohort (5.5%) received cancer diagnoses. For adults age 18 and older, having been hospitalized with a diagnosis of depressive disorder was independently associated with a 1.62-fold (95% CI: 1.12, 2.34) overall increased risk of subsequent cancer during five years of follow-up, after adjusting for residence and socio-demographic characteristics. Conclusion: Our results suggest depression is significantly associated with increased risk of cancer in a rather short follow-up time. Our results call attention to the immediate health impacts of severe depression on patients.