Objective: Large-scale prospective studies do not support an association between neuroticism and extroversion with cancer incidence. However, research on other personality constructs is inconclusive. This longitudinal study examined the associations between four personality measures, Type 1, "suppressed emotional expression"; Type 5, "rational/antiemotional"; hostility; and Type A with cancer incidence.
Methods: Personality measures were available for 13,768 members in the GAZEL cohort study (baseline assessment in 1993). Follow-up for diagnoses of primary cancers was obtained from January 1, 1994 to December 31, 2009. Associations between personality and cancer incidence were evaluated using Cox proportional hazards analyses and adjusted for potential confounders.
Results: During a median follow-up of 16.0 years (range, 9 days-16 years), 1139 participants were diagnosed as having a primary cancer. The mean duration between baseline and cancer diagnosis was 9.3 years. Type 1 personality was associated with a decreased risk of breast cancer (hazard ratio per standard deviation = 0.81, 95% confidence interval = 0.68-0.97, p = .02). Type 5 personality was not associated with prostate, breast, colorectal, or smoking-related cancers, but was associated with other cancers (hazard ratio per standard deviation = 1.17, 95% confidence interval = 1.04-1.31, p = .01). Hostility was associated with an increased risk of smoking-related cancers, which was explained by smoking habits, and Type A was not associated with any of the cancer endpoints.
Conclusions: Several personality measures were prospectively associated with the incidence of selected cancers. These links may warrant further epidemiological studies and investigations about potential biobehavioral mechanisms.