Does solar exposure, as indicated by the non-melanoma skin cancers, protect from solid cancers: Vitamin D as a possible explanation

Sun Exposure and the Risk of Prostate Cancer in the Singapore Prostate Cancer Study: a Case-control Study

“…Canada, Slovenia, Scotland, Finland, Denmark, Iceland, Norway and Sweden) was 1.31 (95%CI 1.23-1.40). There is no significant different between sunny and less sunny countries for prostate cancer among melanoma skin cancers suggesting that sunburn is associated with prostate cancer (Tuohimaa et al, 2007).…”

“…Tuohimaa et al study a cohort of 416,134 cases of skin cancer and 3,776,501 cases of non-skin cancer as a first cancer taken from 13 cancer registries from 11 countries (Tuohimaa et al, 2007). They reported that standardised incidence ratios (SIR) for prostate cancer following nonmelanoma skin cancer (excluding basal cell carcinoma) in sunny countries (Spain, Singapore and Australia) was 0.43 (95%CI 0.23-0.73), and less sunny countries (Canada, Slovenia, Scotland, Finland, Denmark, Iceland, Norway and Sweden) was 1.22 (95%CI 1.18-1.28).…”

Vitamin D and prostate cancer risk: a review of the epidemiological literature

“…The study concluded that vitamin D production in the skin decreased the risk of several solid cancers (especially stomach, colorectal, liver and gallbladder, pancreas, lung, female breast, prostate, bladder and kidney cancers). 117 Similarly, another study was conducted to investigate whether the incidence of prostate cancer and mortality rates in the United States correlated inversely with UVB radiation levels computed from a mathematical model using forecasted ozone levels, cloud levels and elevation. The authors found an inverse correlation between the UVB levels and prostate cancer incidence (R ¼ À0.42, Po0.01) and mortality rates (R ¼ À0.53, Po0.001) for white men and for incidence (R ¼ À0.40, Po0.05) for black men, but the strength of the correlation depended on the season of UVB irradiance.…”

Sun exposure may increase risk of prostate cancer in the high UV environment of New South Wales, Australia: A case–control study

“…It is contradicted by results in a reference cited in that article, which reported that in sunny countries (Australia, Singapore and Spain), the standardized incidence ratio for prostate cancer following diagnosis of nonmelanoma skin cancer (other than basal cell carcinoma) was 0.43 (95% confidence interval, 0.23-0.73) and that for basal cell carcinoma (BCC) was 0.63 (0.44-0.89). 2 The most important risk factor for squamous cell carcinoma is integrated lifetime UVB irradiance, whereas recreational UV irradiance is the strongest risk factor for BCC. 3 Two recent studies reported that odds ratio for cancer changes according to follow-up interval after serum was drawn, changing signs in one study 4 and decreasing toward no effect in another.…”

“…10 There are a number of reasons to not accept the study by Nair-Shalliker et al as valid. The health benefits of UVB exposure and higher serum 25(OH)D levels in reducing the risk of many types of cancer 2,5 and other diseases greatly outweigh any risks associated with them. If the findings of NairShalliker et al were to uncritically accepted as correct, despite its conclusions being drawn from potentially very invalid data, people might avoid exposure to the modest amount of sun they need to prevent many diseases, in the probably vain hope of preventing prostate cancer by sun avoidance.…”