Serious Mental Illness Can Double Cancer Risk

Megan Brooks

August 10, 2012

August 10, 2012 — Adults with schizophrenia or bipolar disorder have a greater than 2-fold increased risk for cancer, particularly lung cancer, a new study suggests.

This study adds to a growing body of research suggesting a higher risk for cancer in patients with serious mental illness.

These latest results suggest that extra efforts should be made to improve cancer prevention and early detection in patients with schizophrenia, Gail L. Daumit, MD, MHS, from Johns Hopkins University School of Medicine, Baltimore, Maryland, and colleagues note.

"Clinicians and mental health system administrators, together with primary care providers, should promote appropriate cancer screening and work to reduce modifiable risk factors, such as smoking, among persons with serious mental illness," they advise.

The study is published in the July issue of Psychiatric Services.

Lifestyle to Blame?

Dr. Daumit and colleagues determined cancer incidence in a cohort of 3317 adult Medicaid beneficiaries with schizophrenia (n = 2315) and bipolar disorder (n = 1002) who were followed from 1994 through 2004.

Compared with the general US population (data from the Surveillance Epidemiology and End Results [SEER] program), the standardized incidence ratio (SIR) for any cancer was 2.6 (95% confidence interval [CI], 2.2 - 3.0) in adults with schizophrenia or bipolar disorder.

By cancer site, the risk was greatest for lung cancer — SIR of 4.7 (95% CI, 3.1 - 6.8) in adults with schizophrenia and 4.1 (95% CI, 2.2 - 7.2) in those with bipolar disorder.

The next greatest risk was for colorectal cancer — SIR, 3.5 (95% CI, 2.1 - 5.5) for schizophrenia and 4.0 (95% CI, 2.0 - 7.2) for bipolar disorder.

Women with schizophrenia or bipolar disorder had a heightened risk of developing breast cancer — SIR, 2.9 (95% CI, 2.1 - 3.9) and 1.9 (95% CI, 1.1 - 3.0), respectively.

"High rates of smoking in the population with serious mental illness likely contribute to lung cancer incidence, and research suggests a possible but inconclusive elevated risk of breast cancer due to low rates of childbearing and increased prolactin levels caused by use of particular psychotropic medications," the investigators write.

"The risk factors contributing to high risk of colon cancer are less understood but may be related to smoking, a sedentary lifestyle, or a diet high in fat and low in fruits and vegetables," they note.

The investigators found no difference in risk for black vs white Medicaid beneficiaries.

The researchers note a "better understanding of how behavioral and pharmacological factors increase cancer risk among persons with serious mental illness, and more information on the extent to which the population receives appropriate cancer screening and treatment, are important in order to improve health in this vulnerable group."

As reported by Medscape Medical News, a recent study showed that malignancies, especially of the breast and lung, are the second most common cause of death in people with schizophrenia, whose risk for cancer death is 50% higher than that of the general population (Limosin et al, Cancer 2009:15;3555-62).

Funding for the study was provided by the National Institute of Mental Health. The authors have disclosed no relevant financial relationships.

Psychiatr Serv. 2012:63:714-7. Abstract


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