There is a lot of speculation that people with schizophrenia have lower rates of cancer than the rest of the population. The results from the research are mixed with some studies finding lower rates, some higher and others little difference. The largest and most sophisticated study of the subject yet attempted looked at thousands of cases of six types of cancer and related them to schizophrenia and bipolar disorder. The results were adjusted to take into account the effects of smoking, body mass index, socio-economic status, other illnesses and prescribed medication. The researchers found that schizophrenia nearly doubled the risk of colon cancer and that schizophrenia patients who took antipsychotic medication had three times the risk of colon cancer. However, people with schizophrenia did have a 47% lower risk of lung cancer. People with bipolar disorder had the same risks for cancer as the rest of the population.
Hippisley-Cox, Julia ... [et al] - Risk of malignancy in patients with schizophrenia and bipolar disorder Archives of General Psychiatry December 2007, 64(12), 1368-1376