Compared with the general population, patients with schizophrenia appear to have an elevated risk of colon cancer and a lower risk of respiratory cancer, according to a report in the Archives of General Psychiatry.

“More research is needed, and the long-term safety of antipsychotics needs further investigation,” Dr. Julia Hippisley-Cox from the University of Nottingham, England told Reuters Health.

Hippisley-Cox and colleagues compared the risks of six common cancers between patients with and without schizophrenia and in patients with bipolar disorder, who have similar lifestyle characteristics as patients with schizophrenia.

The analysis was based on 40,441 cases of breast, colon, rectal, gastroesophageal, prostate and respiratory cancer, matched to up to five comparison subjects.

Compared with patients without schizophrenia, the schizophrenic patients had a nearly three-fold risk of colon cancer and a 52 percent increased risk of breast cancer, but a 48 percent decreased risk of respiratory, the authors report.

The risks did not differ between patients with and without schizophrenia for rectal, gastroesophageal or prostate cancer.

Patients with bipolar disorder did not have a significantly increased or decreased risk for any of the cancers studied.

The risk of colon cancer (but not breast cancer) was increased by more than four-fold among schizophrenic patients who were also prescribed antipsychotic medications, the investigators report, whereas the reduction in respiratory cancer was most marked in the subgroup of patients not taking antipsychotic medications, with a 86 percent decreased risk.

“The higher rate of some common cancers in people with schizophrenia emphasizes the need for proactive monitoring of their physical health,” the authors conclude. “If there is an inherently higher risk of some cancers in people with schizophrenia, it is particularly important to minimize any additional risks associated with lifestyle or prescribed medications.”

SOURCE: Archives of General Psychiatry, December 2007.