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02-05-2012 | Psychology | Article

Cancer risk reduced in schizophrenia patients, relatives


Free abstract

MedWire News: The overall risk for cancer is reduced in patients with schizophrenia and their first-degree relatives, researchers report.

However, Xiangning Chen (Virginia Commonwealth University, Richmond, USA) and colleagues found that women with the mental health disorder were at increased risk for breast, cervical, and endometrial cancers after schizophrenia diagnosis compared with women in the general population.

The team used data from the Swedish Hospital Discharge Register and the Multi-Generation Register to identify 59,233 patients hospitalized with schizophrenia between 1965 and 2008 and their first-degree relatives.

The Swedish Cancer Registry was used to compare cancer incidence among the patients and their relatives with that in the general population over the study period.

In total, 6137 individuals with schizophrenia developed cancer between 1965 and 2008, giving an overall standardized incidence ratio (SIR) of 0.79 compared with the general population.

The decreased overall risk for cancer among schizophrenia patients was more pronounced before diagnosis of the mental health disorder (SIR=0.40) than afterwards.

Indeed, 24 specific cancers showed decreased incidences among schizophrenia patients before diagnosis of the mental health disorder compared with only six afterwards.

Gender-stratified analyses revealed that women with schizophrenia had an increased incidence of breast, cervical, and endometrial cancers after diagnosis compared with the general population, at SIRs of 1.47, 1.39, and 1.34, after adjustment for parity and age at first birth.

The researchers also found that the overall incidence of cancer was reduced in the unaffected parents and siblings of schizophrenia patients compared with the general population, at SIRs of 0.96 and 0.92, respectively.

Chen and team conclude in the Schizophrenia Bulletin: "The significantly decreased incidences of cancers in patients diagnosed with schizophrenia and their unaffected relatives suggest that familiar/genetic factors contributing to schizophrenia may protect against the development of cancer."

They add: "The increased risk of breast, cervical, and endometrial cancers after the first diagnosis of schizophrenia could be attributed to nongenetic factors such as antipsychotics administration, which may justify preventive medical screening."

By Mark Cowen

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