Extroversion and neuroticism and the associated risk of cancer: A Danish cohort study

The authors have investigated the effect of personality, as measured with t he Eysenck Personality Inventory, on the incidence of cancer among 1,031 pe rsons participating in a Danish health survey in 1976-1977 and followed up for 20 years. They thereby accrued a total of 19,993 person-years. The expe cted number of cancer cases was estimated on the basis of age-, sex-, and s ite-specific incidence rates in Copenhagen County Denmark. Overall, 113 mal ignancies were observed among the cohort members between the date of interv iew and December 31, 1996. Since 114.3 were expected from county incidence rates, the standardized incidence ratio was 0.99 (95% confidence interval: 0.81, 1.19). No statistically significant deviation of the relative risk fr om unity was seen for any measure of personality, and no excess risk was se en for any particular type of cancer. A regression model, in which adjustme nt was made for age, sex, calendar period, alcohol consumption, tobacco smo king, psychiatric illness as rated by the interviewing doctor, marital stat us, and social class, showed no excess risk of cancer among persons conside red to be in medium- or high-risk groups according to the Eysenck Personali ty Inventory. The authors' data provide no support for the hypothesis of an association between personality and the risk of cancer.