Schizophrenia and cancer: in 2010 do we understand the connection?

OBJECTIVE: in recent years, there has been a plethora of cancer mortality and incidence data reported in schizophrenia. Despite this, there has been little focus on cancer in schizophrenia guidelines. Additionally, there have been suggestions that schizophrenia may provide inherent protection against cancer. The goal of this review is to establish, using recent data, the incidence and mortality rates for cancer in schizophrenia.
METHOD: we identified systematic reviews and meta-analyses and undertook a search using the Medical Subject Headings' entry terms schizophrenia and neoplasm.
RESULTS: incidence and mortality rates for cancer in schizophrenia are increased, compared with relevant general populations. Data are not uniformly reported and cohort ages tend to be young for expected cancer incidence. Despite the young cohort ages, the incidence of the major cancers-lung and breast-are substantially increased. Confounders are often not measured in the epidemiologic databases. When lung cancer is adjusted for smoking rates, there appears to be a lower risk of lung cancer than expected providing some basis to support an inherently reduced risk of cancer. There may also be a dissonance between incidence and mortality rates that suggest a prejudice against either diagnosis or treatment of these vulnerable patients.
CONCLUSION: a single definitive study of schizophrenia and cancer is unfeasible, and future research will lean heavily on systematic review and meta-analysis. Researchers should report cancer data to include age and follow-up data and cohort overlap. Cancer accounts for almost an equivalent mortality as cardiovascular disease.