Prostate cancer risk and exposure to ultraviolet radiation: further support for the protective effect of sunlight Dhaval Bodiwala a,b , Christopher J. Luscombe a , Samson Liu a , Mark Saxby a , Michael French a , Peter W. Jones c , Anthony A. Fryer b , Richard C. Strange b, * a Department of Urology, North Staffordshire Hospital, Stoke-on-Trent, Staffordshire, UK b Clinical Biochemistry Research Laboratory, Keele University School of Medicine, North Staffordshire Hospital, Stoke-on-Trent, Staffordshire, UK c Department of Mathematics, Keele University, Keele, Staffordshire, UK Received 10 September 2002; received in revised form 26 November 2002; accepted 27 November 2002 Abstract Recent studies have suggested that exposure to ultraviolet (UV) radiation may be protective to some internal cancers including that in the prostate. We describe a confirmatory study in 212 prostatic adenocarcinoma and 135 benign prostatic hypertrophy patients designed to determine whether previous findings showing a protective effect for UV exposure could be reproduced. We used a validated questionnaire to obtain data on aspects of lifetime exposure to UV. The data confirmed that higher levels of cumulative exposure, adult sunbathing, childhood sunburning and regular holidays in hot climates were each independently and significantly associated with a reduced risk of this cancer. q 2002 Elsevier Science Ireland Ltd. All rights reserved. Keywords: Prostate cancer; Ultraviolet radiation; Benign prostatic hypertrophy; Sunbathing; Cumulative exposure 1. Introduction It is widely recognized that exposure to ultraviolet radiation (UV) in sunlight can have harmful effects including increasing skin cancer risk. However, studies using a variety of experimental approaches and prompted by the geographical variation in mortality rates of various cancers have shown that exposure to UV can lead to decreased incidence and mortality from breast, ovarian, prostate and other cancers [1–7]. The mechanism for these associations is suggested to be via increased vitamin D production. Thus, the availability of this vitamin, which has inhibiting effects on proliferation and de-differen- tiation of various tumour cells, is largely determined by its UV-mediated synthesis in skin [2,8,9]. We previously demonstrated a protective effect of UV on prostate cancer risk using a validated questionnaire to assess acute and chronic exposure in 210 cancer and 155 benign prostatic hypertrophy (BPH) patients recruited between October 1999 and May 2000 [10,11]. Increased cumulative lifetime 0304-3835/02/$ - see front matter q 2002 Elsevier Science Ireland Ltd. All rights reserved. doi:10.1016/S0304-3835(02)00710-3 Cancer Letters 192 (2003) 145–149 www.elsevier.com/locate/canlet * Corresponding author. Clinical Biochemistry Research Laboratory, Keele University School of Medicine, North Staffordshire Hospital, Staffordshire, UK. Tel.: þ 44-1782- 554667; fax: þ 44-1782-554646. E-mail address: paa00@keele.ac.uk (R.C. Strange).