Occurrence of cancer among people with mental health claims in an insured population

Objective: The objective of this research is to determine whether people with mental disorders are at increased risk for the subsequent development of malignancies compared with people without mental disorders. Methods: This is a retrospective cohort study of administrative claims data. The study population included 722,139 adults who filed at least one medical claim from 1989 to 1993. The mental disorder cohort included people with a) one psychiatric hospitalization, b) one outpatient psychiatrist visit, or c) two outpatient mental health claims occurring at least 6 months before a cancer claim. The controls were subjects filing claims for medical services who had no mental health visits. We calculated age-stratified odds ratios (ORs) for development of malignancy. Results: People with mental disorders were no more or less likely to develop a malignancy than those without after adjusting for age (women: OR, 1.03; 95% confidence interval [CI], 0.95-1.12; men: OR, 1.10; 95% CI, 0.97-1.24). People with mental disorders, however, developed cancer at younger ages and had increased odds of primary central nervous system tumors (women: OR, 2.12; 95% CI, 1.40-3.21; men: OR, 2.09; 95% CI, 1.22-3.59) and respiratory system cancers (women: OR, 1.57; 95% CI, 1.13-2.19; men: OR, 1.52; 95% CI, 1.09-2.12). Conclusions: Insured people with mental disorder claims had an increased risk of certain malignancies and developed malignancies at younger ages. The increased odds of respiratory tumors are likely secondary to increased rates of smoking among people with mental disorders and support use of smoking cessation interventions in this population. The increased odds for brain tumors may reflect only the early presence of mental symptoms, or a true association between the two conditions. Further study of these findings is mandated.