Cancer mortality in patients with schizophrenia: an 11-year prospective cohort study

Schizophrenia has been associated with a rate of premature mortality that is 2 to 3 times higher than that in the general population. Although the role of cancer in this excess mortality remains unclear, previous incidence or mortality studies found contradictory results.

In 1993, a large prospective study was initiated in a cohort of 3470 patients with schizophrenia to examine cancer-related mortality and predictors. Standardized mortality ratios (SMRs) were calculated, adjusting for age and sex relative to a representative sample of the French general population.

During the 11-year follow-up, 476 (14%) patients died; the mortality rate was thus nearly 4-fold higher than in the general population. Cancer was the second most frequent cause of mortality (n=74), with a global SMR of 1.5 (95% confidence interval [95% CI], 1.2-1.9). For all cancers, the SMRs were 1.4 (not significant) for men and 1.9 (95% CI, 1.4-2.8) for women. For men, lung cancer was the most frequent localization (n=23; 50%), with an SMR of 2.2 (95% CI, 1.6-3.3). For women, breast cancer was the most frequent localization (n=11; 39%), with an SMR of 2.8 (95% CI, 1.6-4.9). In comparison with patients who did not die of cancer, there were 2 significant baseline predictors of death by lung cancer in the final logistic regression model: duration of smoking and age>38 years.

The results of the current study demonstrated an increased risk of mortality by cancer in patients with schizophrenia, especially for women from breast cancer and for men from lung cancer.