Adult body size, sexual history and adolescent sexual development, may predict risk of developing prostate cancer: Results from the New South Wales Lifestyle and Evaluation of Risk Study (CLEAR) Visalini Nair-Shalliker 1,2,3 , Sarsha Yap 1 , Carlos Nunez 1 , Sam Egger 1 , Jennifer Rodger 1 , Manish I Patel 2,4 , Dianne L O’Connell 1,2,5 , Freddy Sitas 2,6,7 , Bruce K Armstrong 2,8 and David P Smith 1,2,9 1 Cancer Research Division, Cancer Council New South Wales (NSW), Sydney, NSW, Australia 2 Sydney School of Public Health, Sydney Medical School, The University of Sydney, Sydney, NSW, Australia 3 Department of Clinical Medicine, Macquarie University, Sydney, Australia 4 Department of Urology, Westmead Hospital, Westmead, NSW, Australia 5 School of Medicine and Public Health, University of Newcastle, Newcastle, NSW, Australia 6 School of Public Health and Community Medicine, University of New South Wales, NSW, Australia 7 Menzies Centre for Health Policy, Sydney Medical School, The University of Sydney, NSW, Australia 8 School of Population Health, University of Western Australia, Perth, Western Australia, Australia 9 Menzies Health Institute, Queensland, Griffith University, Gold Coast, Queensland, Australia Prostate cancer (PC) is the most common non-cutaneous cancer in men worldwide. The relationships between PC and possible risk factors for PC cases (n 5 1,181) and male controls (n 5 875) from the New South Wales (NSW) Cancer, Life- style and Evaluation of Risk Study (CLEAR) were examined in this study. The associations between PC risk and paternal history of PC, body mass index (BMI), medical conditions, sexual behaviour, balding pattern and puberty, after adjusting for age, income, region of birth, place of residence, and PSA testing, were examined. Adjusted risk of PC was higher for men with a paternal history of PC (OR 5 2.31; 95%CI: 1.70–3.14), personal history of prostatitis (OR 5 2.30; 95%CI: 1.44–3.70), benign prostatic hyperplasia (OR 5 2.29; 95%CI: 1.79–2.93), being overweight (vs. normal; OR 5 1.24; 95%CI: 0.99–1.55) or obese (vs. normal; OR 5 1.44; 95%CI: 1.09–1.89), having reported more than seven sexual part- ners in a lifetime (vs. < 3 partners; OR 5 2.00; 95%CI: 1.49–2.68), and having reported more than 5 orgasms a month prior to PC diagnosis (vs. 3 orgasms; OR 5 1.59; 95%CI: 1.18–2.15). PC risk was lower for men whose timing of puber- ty was later than their peers (vs. same as peers; OR 5 0.75; 95%CI: 0.59–0.97), and a smaller risk reduction of was observed in men whose timing of puberty was earlier than their peers (vs. same as peers; OR 5 0.85; 95%CI: 0.61– 1.17). No associations were found between PC risk and vertex balding, erectile function, acne, circumcision, vasectomy, asthma or diabetes. These results support a role for adult body size, sexual activity, and adolescent sexual development in PC development. Key words: Prostate cancer, puberty, balding, obesity, sexual activity Abbreviations: ARIA plus: Accessibility Remoteness Index of Australia; BMI: body mass index; BPH: Benign prostatic hyperplasia; CLEAR: Cancer, Lifestyle and Evaluation of Risk Study; CPS: Cancer of the Prostate in Sweden study; DHT: dihydrotestosterone; E: estradiol; MCCS: Melbourne Collaborative Cohort Study; NSW: New South Wales; NSWCR: NSW Cancer Registry; OR: odds ratio; PC: prostate cancer; PSA: prostate specific antigen; T: testosterone; WCRF: World Cancer Research Fund. Additional Supporting Information may be found in the online version of this article. Conflict of interest: All authors declare no conflict of interest. Financial support: The Cancer Council New South Wales. Grant sponsor: Australian National Health and Medical Research Council Training Fellowships; Grant number: APP1016598 DOI: 10.1002/ijc.30471 History: Received 28 Apr 2016; Accepted 26 Sep 2016; Online 14 Oct 2016 Correspondence to: Visalini Nair-Shalliker, Cancer Research Division, Cancer Council NSW, 153 Dowling Street, Woolloomooloo 2011, NSW Australia, Tel.: 1612 9334 1410; Fax: 1612 8302 3550, E-mail: visalinin@nswcc.org.au Cancer Epidemiology Int. J. Cancer: 140, 565–574 (2017) V C 2016 UICC International Journal of Cancer IJC