Risk of malignancy in patients with schizophrenia or bipolar disorder: nested case-control study.
BACKGROUND
There is conflicting evidence on whether people with schizophrenia have a different risk of cancer from that of the general population.


OBJECTIVE
To determine the risk of 6 common cancers in patients with schizophrenia or bipolar disorder.


METHODS
Population-based, nested, case-control study.


METHODS
A total of 454 practices contributing to the QRESEARCH general practice database.


METHODS
We analyzed 40,441 incident cases of 6 cancers (breast, colon, rectal, gastroesophageal, prostate, and respiratory) and up to 5 controls per case matched by single year of age, sex, general practice, and calendar time.


METHODS
Odds ratios (ORs) for cancer risk associated with schizophrenia and bipolar disorder, adjusting for smoking, body mass index, socioeconomic status, comorbidities, and prescribed medications, including antipsychotics.


RESULTS
For breast cancer, we identified 10,535/50,074 cases/controls; colon cancer, 5108/24,458; rectal cancer, 3248/15,552; gastroesophageal cancer, 3854/18,477; prostate cancer, 10,190/48,748; and respiratory cancer, 7506/35,981. After adjustment, patients with schizophrenia had a 190% increased colon cancer risk (adjusted OR, 2.90; 95% confidence interval [CI], 1.85-4.57), a marginal increased breast cancer risk (adjusted OR, 1.52; 95% CI, 1.10-2.11), and a 47% decreased respiratory cancer risk (adjusted OR, 0.53, 95% CI, 0.34-0.85). Patients with schizophrenia taking antipsychotics had a 308% increased colon cancer risk (adjusted OR, 4.08; 95% CI, 2.43-6.84). Patients with bipolar disorder had cancer risks similar to patients with neither condition after adjustment.


CONCLUSIONS
Patients with schizophrenia have a significantly higher risk of colon cancer and a lower risk of respiratory cancer compared with patients without schizophrenia after adjustment for confounders. In contrast, the risks of cancer in patients with and without bipolar disorder are similar, suggesting that residual confounding is unlikely to explain the findings. The increased risk of colon cancer is particularly marked in patients with schizophrenia who take antipsychotic medications.
Division of Primary Care, University of Nottingham, 13th Floor Tower Bldg, University Park, Nottingham NG7 2RD, England. julia.hippisley-cox@nottingham.ac.uk
Julia
J
Hippisley-Cox
Yana
Y
Vinogradova
Carol
C
Coupland
Chris
C
Parker
D000368:Aged; D014150:Antipsychotic Agents / Q000627:therapeutic use; D001714:Bipolar Disorder / Q000453:epidemiology*; D001943:Breast Neoplasms / Q000453:epidemiology; D003110:Colonic Neoplasms / Q000453:epidemiology; D003710:Demography; D004358:Drug Therapy / Q000706:statistics & numerical data; D004938:Esophageal Neoplasms / Q000453:epidemiology; D005260:Female; D005770:Gastrointestinal Neoplasms / Q000453:epidemiology; D006801:Humans; D015994:Incidence; D008175:Lung Neoplasms / Q000453:epidemiology; D008297:Male; D008875:Middle Aged; D009369:Neoplasms / Q000453:epidemiology*; D015995:Prevalence; D011471:Prostatic Neoplasms / Q000453:epidemiology; D012004:Rectal Neoplasms / Q000453:epidemiology; D012307:Risk Factors; D012559:Schizophrenia / Q000188:drug therapy / Q000453:epidemiology*
D014150:Antipsychotic Agents