A number of previous studies have documented a low rate of cancer in patients with schizophrenia. However, the results of a large study conducted in Denmark indicate that families with schizophrenia are not protected genetically against cancer.

Dr. Susanne Oksbjerg Dalton from the Institute of Cancer Epidemiology in Copenhagen told Reuters Health that an increased cell turnover rate in schizophrenia might confer protection against cancer. “If this is so, the lower risk for cancer could be hypothesized to also be apparent in first-degree relatives of persons with schizophrenia,” she explained.

To test this idea, Dalton’s group turned to the Danish Central Population Registry, identifying close to 2 million parents of offspring born after 1935, and the Danish Psychiatric Central Register, identifying close to 20,000 parents of offspring with schizophrenia.

Overall, there was no difference in the risk of cancer in the parents of schizophrenic children compared with parents of non-schizophrenic children, the investigators report in the American Journal of Psychiatry.

Mothers of schizophrenic children had an increased risk of lung cancer and both mothers and fathers of schizophrenic children showed a tendency toward a decreased risk of leukemia.

“All in all, our study does not offer support for a genetic predisposition for schizophrenia and protection against the development of malignancies,” Dalton told Reuters Health. In fact, parents of people with schizophrenia appeared to have no consistently different pattern of cancer risk compared with other parents.

SOURCE: American Journal of Psychiatry, May 2004.