Prostate cancer susceptibility is mediated by interactions between exposure to ultraviolet radiation and polymorphisms in the 5' haplotype block of the vitamin D receptor gene.

Vitamin D receptor (VDR) polymorphisms are prostate cancer risk candidates. We determined if SNPs in haplotype block sub-regions C2 (SNPs C2-1, G/C(3436), C2-2, A/G(3944)) or C1 (C1-1, C/T(20965), C1-2, C/T(30056)) are associated with risk in an ultraviolet radiation (UVR)-dependent manner. In men with very low exposure, SNPs in both sub-regions were associated with risk. Various haplotypes in haplotype block C including G(3436)-A(3944)-C(20965)-C(30056), (G or C)-A-C-C and G-A-(C or T)-C were significantly associated with increased risk (odds ratios between 1.95 and 2.37). These findings suggest various block C SNPs are associated with prostate cancer risk via a mechanism involving exposure to sunlight.

Associations between G/A1229, A/G3944, T/C30875, C/T48200 and C/T65013 genotypes and haplotypes in the vitamin D receptor gene, ultraviolet radiation and susceptibility to prostate cancer.

Ultraviolet radiation (UVR) may protect against prostate cancer via a mechanism involving vitamin D. Thus, the vitamin D receptor (VDR) gene is a susceptibility candidate, though published data are discrepant. We studied the association of prostate cancer risk with five VDR single nucleotide polymorphisms (SNPs): G/A(1229) (SNP 1), A/G(3944) (SNP 2), T/C(30875) (SNP 3), C/T(48200) (SNP 4) and C/T(65013) (SNP 5), in 430 cancer and 310 benign prostatic hypertrophy (BPH) patients. The SNP 2 GG genotype frequency was lower in cancer than BPH patients (odds ratio = 0.63, 95% CI = 0.41-0.98, p = 0.039). SNPs 1 and 2, and SNPs 4 and 5, were in linkage disequilibrium. Two copies of haplotypes comprising SNPs 1-2, G-G (odds ratio = 0.63, p = 0.039), SNPs 2-3 G-C (odds ratio = 0.45, p = 0.008) and SNPs 1-2-3 G-G-C (odds ratio = 0.44, p = 0.006), but not SNPs 1-3, G-C (odds ratio = 0.81, p = 0.34), were associated with reduced risk (reference, no copies of the haplotypes). These associations were observed after stratification of subjects by extent of UVR exposure. These data show that SNP 2 GG genotype mediates prostate cancer risk, complementing studies reporting this allele is protective in malignant melanoma pathogenesis. They further suggest that published associations of risk with SNP 1 may result from linkage disequilibrium with SNP 2.

Is high cord radical orchidectomy always necessary for testicular cancer?

BACKGROUND: Radical high cord inguinal orchidectomy remains the standard for diagnosis, staging and treatment of testicular neoplasms. Low cord orchidectomy is an alternative to the high cord orchidectomy. OBJECTIVE: To test the hypothesis that there is no difference in relapse rate or mortality between high and low cord orchidectomy for the treatment of testicular cancer. METHODS: A retrospective study was undertaken of all orchidectomies performed for testicular cancer at our hospital between 1981 and 2002. RESULTS: Overall, 120 high cord orchidectomies and 102 low cord orchidectomies were performed for testicular cancer between 1981 and 2002 at our hospital. Analysis showed that there was no significant difference in the mean age of the patients, the rate of relapse, mean time to relapse or survival between surgical approach for stage 1 tumours. For stage 2-4 tumours, there were not sufficient numbers to comment on the statistical significance of relapse or survival differences. CONCLUSIONS: The trend suggests that there is no statistically significant difference in the rate of relapse and mortality between high and low cord orchidectomy for clinically stage 1 tumours. We would, therefore, advocate either a high or low cord orchidectomy for clinically stage 1 tumours.

Polymorphisms in the vitamin D receptor gene, ultraviolet radiation, and susceptibility to prostate cancer.

Ultraviolet radiation (UVR) exposure may protect against prostate cancer development via a mechanism involving vitamin D. The vitamin D receptor (VDR) gene is therefore a candidate susceptibility factor for prostate cancer. This possibility has been previously investigated with conflicting results. We examined the association of VDR genotypes (variants at the CDX-2, Fok1, and Taq1 sites), haplotypes, and genotype combinations with risk by studying 368 prostate cancer and 243 benign prostatic hypertrophy (BPH) patients. CDX-2, Fok1, and Taq1 genotype and haplotype frequencies were not significantly different in cancer and BPH patients. As the impact of VDR polymorphisms may depend on UVR exposure, we studied associations of variants with risk in men stratified into low (below median) and high (above median) cumulative exposure/year groups. In men with UVR exposure above the median (1,100 hr/year), CDX-2 GA and AA (odds ratios [OR] = 2.11 and 2.02, respectively) and Fok1 ff (OR = 2.91) were associated with increased prostate cancer risk. No associations were observed for Taq1 genotypes. Of the genotype combinations, relative to all other CDX-2 and Taq1 and combinations, GGTT (P = 0.022, OR = 0.30), and relative to all other Fok1 and Taq1 combinations, FFTT (P = 0.026, OR = 0.35) were associated with reduced prostate cancer risk in the presence of the main effects. None of the other two- or three-genotype combinations was associated with risk. These data indicate that VDR variants influence prostate cancer risk and that this association is dependent on the extent of UVR exposure.

Associations between prostate cancer susceptibility and parameters of exposure to ultraviolet radiation.

Low sunlight exposure confers increased prostate cancer risk. In a study conducted in northern England, we investigated how combinations of exposure measures affect this risk. Recursive partitioning was used to identify combinations of exposure parameters that distinguished 453 prostate cancers from 312 benign hypertrophy patients. Sunbathing score most significantly defined cancer patients; 78.7% men with low scores (8.0) had cancer. These subgroups were stratified by childhood sunburning, holidays in a hot climate and skin type such that subgroups with a 13.0-fold increased risk of cancer were identified.

Susceptibility to prostate cancer: studies on interactions between UVR exposure and skin type.

Recent studies have proposed that exposure to ultraviolet radiation (UVR) protects against development of some internal cancers including that in prostate. This effect may be mediated by UVR-induced cutaneous synthesis of vitamin D. It is also proposed that ability to pigment in response to UVR will influence susceptibility to prostate cancer through its effects on vitamin D synthesis. We wished to determine first, whether ability to pigment, as assessed by skin type, influences the extent of exposure to UVR, secondly, whether skin type is associated with prostate cancer susceptibility and thirdly, whether such an effect is mediated by the extent of UVR exposure. We studied 453 prostatic adenocarcinoma and 312 benign prostatic hypertrophy (BPH) patients using a validated questionnaire to assess two parameters of exposure; months of cumulative exposure per year and adult sunbathing score. We used analysis of variance to show that cancer cases with sun-sensitive skin (skin type 1) had lower cumulative exposure per year (P = 0.014) and sunbathing scores (P < 0.0001) than those with type 4, possibly because of a tendency to avoid exposure. Further, cumulative exposure per year and sunbathing score were significantly lower in cancer compared with BPH patients (P < 0.001 and P < 0.001, respectively). While the proportion of subjects with skin types 1 and 2 was lower in cancer than BPH patients, these were not significantly different (logistic regression analysis, skin type 1 versus type 4; P = 0.11). We used recursive partitioning to determine if skin type influenced susceptibility to prostate cancer in subgroups stratified by exposure. Analysis of the data showed that in men with low sunbathing scores, skin type 1 conferred protection compared with skin types 2-4 (OR = 4.78, 95% CI 3.01-8.25, P < 0.0009). These findings indicate that susceptibility to prostate cancer is in part determined by extent of exposure to UVR and that ability to pigment mediates this effect.

Prostate cancer risk and exposure to ultraviolet radiation: further support for the protective effect of sunlight.

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.