People with schizophrenia have a 50 percent higher risk of death from cancer compared to people in the general population. That was the conclusion of a new study published in the August 1, 2009 issue of CANCER, a peer-reviewed journal of the American Cancer Society. The study's results suggest that extra efforts should be made to improve cancer prevention and early detection in patients with schizophrenia.
Schizophrenia is associated with an increased incidence of premature death, in part due to a high rate of suicide among individuals with the disease. However, suicide alone does not account for the shortened life expectancy seen in schizophrenia patients. Some studies have indicated that cancer mortality may play a role, but other data suggest that cancer rates are actually lower among individuals with schizophrenia compared with the general population.
To more precisely determine the prevalence of cancer in patients with schizophrenia, Prof. Frédéric Limosin of the University of Reims, Robert Debré Hospital, in Reims, France and colleagues prospectively studied 3,470 patients with schizophrenia and tracked cancer incidence beginning in 1993. The investigators also sought to identify characteristics that might help predict which schizophrenic patients are likely to develop cancer.
The researchers found that 476 (14%) patients died during the eleven years of the study, a death rate was nearly four-fold higher than in the general population. Seventy-four patients died of cancer, making it the second most frequent cause of death behind suicide. In men with schizophrenia, the risk of death due to lung cancer was significantly higher than that in the general population, but the risk of overall cancer death was not significantly higher. In women, the risk of overall mortality was significantly higher than among the general population. The proportion of patients who were smokers was significantly higher in the study population than in the general population (56.3 vs. 33.0%). In female schizophrenic patients, the risk of death due to breast cancer was significantly higher than in the general population. The authors say possible explanations include is a delay in diagnosis due to patients paying less attention to symptoms; the difficulty for schizophrenic patients to benefit from optimum treatment; and less compliance to treatment.
Prof. Limosin and his collaborators noted that additional studies should further examine cancer rates in individuals with schizophrenia and should better define the characteristics of tumors that arise in these patients.