© 2006 The Royal College of Psychiatrists
Correspondence |
Cancer and schizophrenia
Mental Health Services, Ministry of Health, 2 Ben Tabai Street, Jerusalem 93591, Israel.
Mental Health Services, Ministry of Health, Jerusalem, Israel
Correspondence: E-mail: levavm{at}zahav.net.il
EDITED BY KIRIAKOS XENITIDIS and COLIN CAMPBELL
The negative finding of the recent paper by Goldacre et al (2005) is an important addition to studies attempting to confirm or disprove the ‘epidemiologic puzzle’ (Jablensky & Lawrence, 2001), but the evidence remains ambiguous regarding the overall risk of cancer in people with schizophrenia. In three of five comparisons with reference populations conducted between 1992 and 2003 (see Grinshpoon et al, 2005), males with schizophrenia had a reduced risk of cancer. No reduction was found among females in four comparisons but decreased risk was reported in one of two comparisons of both males and females. Two recent studies (Dalton et al, 2005; Grinshpoon et al, 2005) mostly found reduced risk. When evaluating these results, it is important to recall that people with schizophrenia face many health and service hazards that may increase their risk for cancer (Grinshpoon et al, 2005). We therefore suggest that results in this area should not be stopped prematurely, especially since one study (Lichtermann et al, 2001), but not another (Dalton et al, 2004), found a reduced risk of cancer among first-degree relatives of patients with schizophrenia, an indication of a genetic factor (Park et al, 2004).
The study by Goldacre et al (2005) had some limitations, as acknowledged by the authors. We wonder whether a diagnosis of schizophrenia at the time of the first admission may not constitute an additional limitation. Patients admitted with an early diagnosis of schizophrenia but who later received other psychiatric diagnoses might have diluted the risk (Carney et al, 2004), whereas others who did not have a diagnosis of schizophrenia on first admission but did on later contact might have been lost to the enquiry. We also wonder whether the decision to exclude some people from the reference population for selected cancers was sound. Admittedly, dietary factors may be imputed for those conditions selected for elimination as well as for cancer risk. We look forward to a repetition of the analysis after their inclusion.
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