Cancer Risk Varies in Patients with Schizophrenia

NEW YORK DEC 20, 2007 (Reuters Health) - Compared to 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 December issue of 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.

Dr. 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 incident cases of breast, colon, rectal, gastroesophageal, prostate and respiratory cancer, matched to up to 5 controls per case.

For patients with schizophrenia, the odds ratio for colon cancer was 2.9, for breast cancer it was 1.52, but for respiratory cancer it was only 0.52, compared with patients without schizophrenia, 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 increased risk of colon cancer (but not breast cancer) was stronger in the subgroup of patients with schizophrenia also prescribed antipsychotic medications (OR, 4.08), the investigators say, whereas the reduction in respiratory cancer was most marked in the subgroup of patients not taking antipsychotic medications (OR, 0.14).

"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."

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