CLINICAL CONTEXT
Adults with serious and persistent mental illness such as schizophrenia and bipolar disorder experience a higher risk for premature mortality vs individuals without these mental illnesses, and a previous study by Piatt and colleagues analyzed the potential causes of early death among adults with serious mental illness. Their research, which was published in the July 2010 issue of Psychiatric Services, found that a higher rate of accidents and suicide had the biggest impacts on increasing the risk for mortality among individuals with serious mental illness. Other important causes of death specifically among adults with serious mental illness were liver disease and septicemia.
Cancer also promoted a higher risk for early mortality among adults with serious mental illness, but not all research has supported a higher risk for cancer among individuals with schizophrenia and bipolar disorder. The current study by Daumit and colleagues evaluates the cancer risk associated with serious mental illness.
STUDY SYNOPSIS AND PERSPECTIVE
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 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 by Limosin and colleagues 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 (Cancer. 2009:15;3555-3562).
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
STUDY HIGHLIGHTS
- The investigators conducted their research as a retrospective study of adult beneficiaries of Medicaid in Maryland. All study participants were between 21 and 62 years old and had either a diagnosis of schizophrenia or bipolar disorder with disability.
- The main study outcome was incident cancer, which was determined from Medicaid claims data. The data from individuals with serious mental illness were compared vs national norms from the Surveillance Epidemiology and End Results program.
- The study cohort included 2315 adults with schizophrenia and 1002 individuals with bipolar disorder. The mean age of study patients was approximately 42 years, and there was a slight preponderance of women in the overall cohort. The study was fairly evenly divided among African American and white participants.
- Overall, the total cancer incidence was 2.6 times higher among adults with serious mental illness vs adults without serious mental illness.
- Both schizophrenia and bipolar disorder were associated with a significantly increased risk for cancer.
- The risk for lung cancer was 4 times higher among adults with serious mental illness, and the risk for colorectal cancer was similarly elevated.
- The risk for breast cancer was elevated to a slightly greater extent among women with schizophrenia vs women with bipolar disorder.
- Serious mental illness was not associated with a higher risk for prostate cancer.
- Patients’ race did not affect the higher risk for cancer associated with serious mental illness.
CLINICAL IMPLICATIONS
- Previous research by Piatt and colleagues has demonstrated that accidents and suicide are the most important causes of early death among individuals with serious mental illness vs adults without serious mental illness.
- In the current study by Daumit and colleagues, schizophrenia and bipolar disorder were associated with an overall higher risk for cancer, including lung, colorectal, and breast cancers.