Treatment Online

Schizophrenics Have Different Rates of Cancer
> 12/5/2007 2:35:44 PM

In 1909, the Board of Control of the Commissioners in Lunacy for England and Wales posited that schizophrenia offers some protection against cancer. Since that early hypothesis, there have been a number of small studies that made the issue seem unimportant because of contradictory or unimpressive results. A new study conducted by Dr. Julia Hippisley-Cox uses a larger pool and more rigorous analysis to show that there are significant differences in cancer rates between schizophrenics and the general population.

Dr. Hippisley-Cox gained full access to the QRESEARCH database, which contains the clinical records of more than 10 million United Kingdom citizens. Her analysis compared citizens with schizophrenia to healthy controls and to those with another serious mental illness, bipolar disorder, to see if schizophrenia is a unique risk factor for cancer. The QRESEARCH database contains information on each patient's body mass index, smoking status, and socioeconomic rank, all of which were compensated for. Controlling for these factors was crucial, because schizophrenics are much more likely to smoke and run into economic problems. Previous studies that failed to find cancer rate differences could easily have been muddled by failing to take these confounding factors into account. Though Dr. Hippisley-Cox was very thorough, she was not able to correct for all possible cancer risk factors, most significantly diet. However, since body mass index is related to diet, this problem may have been minimized.

Dr. Hippisley-Cox found that there are large abnormalities in the cancer rates of schizophrenics, but that the rates are either higher or lower than the average depending on the type of cancer. Much of the difference cancels out when viewed from afar, which may be why earlier studies were so inconclusive. It seems that the Commissioners in Lunacy only had half the story a century ago. Patients with schizophrenia had a 52% and 47% decreased risk for breast and respiratory cancer respectively, and a staggering 190% increased risk for colon cancer. This increased risk rose to 308% percent for patients taking antipsychotic medication. Bipolar patients showed none of these risk differences.

While future research will have to further explore these apparent anomalies, Dr. Hippisley-Cox's findings should alert doctors to the unique cancer risks faced by their schizophrenic patients. Schizophrenics should be given frequent screenings for colon cancer, especially if they are on antipsychotics. They should also be guided towards a lifestyle that minimizes cancer risk. In addition to these practical implications, the QRESEARCH study may also point towards a better theoretical understanding of schizophrenia. If it is not lifestyle, but rather some physiological factor, that elevates cancer risk, then researchers can better understand the illness by examining the mechanism by which it makes the body more vulnerable to some cancers but more resistant to others.

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