Diabetes and the risk of prostate cancer A Tavani 1 , S Gallus 1 , C Bosetti 1 , A Tzonou 2 , P Lagiou 2 , E Negri 1 , D Trichopoulos 3 , C La Vecchia 1,4 (Received 26 October 2000; accepted 2 January 2001) The relation between diabetes and prostate cancer risk was investigated in a combined analysis of two hospital-based case– controlstudiesconductedinItalyandGreece,between1985and1997.Caseswere608menwithincidentprostatecancer,and controls were 1008 men admitted to hospital for acute non-neoplastic diseases. No material association between diabetes and prostate cancer was observed, with a multivariate odds ratio (OR) of 1.07 (95% confidence interval (CI) 0.68–1.66). Compared with men without diabetes, there was a non-significant increased risk of prostate cancer in those diagnosed with diabeteswithinthelast5years(OR2.04),whiletheORswere0.96and0.78respectivelyforadiagnosisofdiabetes5–9years and 10 years ago.  c 2002 Lippincott Williams & Wilkins. Key words: Case–control studies, diabetes mellitus, prostatic neoplasms, risk factors. Introduction Epidemiological studies on the possible relation between diabetes and prostate cancer are controver- sial. In a case–control study of 300 cases and 400 controls (Wynder et al., 1971), history of diabetes was reported by 7% of cases and 6% of controls. An inverse association was found in the Rancho Bernar- do cohort study (Thompson et al., 1989), with a relative risk (RR) of 0.3, based on 100 cases, and in a cohort of Swedish men (Adami et al., 1991) discharged from hospital with a diagnosis of diabetes (RR 0.7, based on 224 cases). Conversely, in the American National Health and Nutrition Survey I (Steenland et al., 1995) the risk of prostate cancer was non-significantly elevated in men with diabetes (RR 1.45), and no association between diabetes and risk of prostate cancer emerged among men screened as part of the Multiple Risk Factor Intervention Trial (Coughlin et al., 1996), the RR being 0.90 based on 14 deaths. In a record-linkage prospective study from Den- mark (Wideroff et al., 1997), 505 cases of prostatic cancer were registered from a cohort of men hospitalized for diabetes, corresponding to RR of 0.9; the risk was similar in men diagnosed with diabetes when aged o50 years or 50 years. More- over, the Health Professional Follow-up Study (Giovannucci et al., 1998), based on 1411 cases of prostate cancer, found an overall RR of 1.05 for diabetes; the RRs of prostate cancer were 1.24 in men with a diagnosis of diabetes made r5 years before, 0.66 in those with a diagnosis made 6–10 years before, and 0.54 in those with a diagnosis made 410 years before. However, the 13-year follow-up of the Cancer Prevention Study (Will et al., 1999) found a rate ratio for prostate cancer in all diabetic men of 1.05, based on 2523 cases; the rate ratio was 1.56 when the diagnosis of diabetes was made 5 years before, and 0.84 for diagnosis of diabetes made o5 years before. We combined the data from two case–control studies conducted in Italy and Greece, including information on several relevant covariates, in order to assess in a large data set the relation between diabetes and prostate cancer risk (La Vecchia et al., 1994; Hsieh et al., 1999). Subjects and methods Data were derived from two hospital-based case– control studies on prostate cancer, conducted in Italy and Greece, whose general design has already been described (Talamini et al., 1992; Hsieh et al., 1999). 1 Istituto di Ricerche Farmacologiche Mario Negri, Via Eritrea 62, 20157 Milan, Italy. 2 Department of Hygiene and Epidemiology, University of Athens Medical School, Goudi, Athens 115 27, Greece. 3 Department of Epidemiology and Harvard Center for Cancer Prevention, Harvard School of Public Health, 677 Huntington Avenue, Boston, MA 02115, USA. 4 Istituto di Statistica Medica e Biometria, Universita ` degli Studi di Milano, Via Venezian 1, 20133 Milan, Italy. Correspondence to: A Tavani. Fax: (þ39) 02 3900 1916. E-mail: tavani@marionegri.it 0959-8278  c 2002 Lippincott Williams & Wilkins European Journal of Cancer Prevention. Vol 11. 2002 125 European Journal of Cancer Prevention 2002, 11, 125–128