Prostate cancerExposure to sunlight

There is good evidence that exposure to ultraviolet (UV) radiation reduces the risk of prostate cancer (PCa).

A study in the UK found that vitamin D receptor variants influence PCa risk and that this association is dependent on the extent of UVR exposure1.

Using cross-sectional data from the United States, significant inverse associations were found for men born in a region of high solar radiation (relative risk (RR), 0.49, 95% confidence interval (CI), 0.27-0.90 for high versus low solar radiation), with a slightly greater reduction for fatal than for nonfatal PCa. In a subsequent paper, it was reported that the odds ratio (OR) of prostate cancer with respect to childhood sunburn was 0.38 (0.26-0.57)2. 

A study in the United States on 161 non-Hispanic whites with PCa found that solar radiation in state of birth had a statistically significant inverse correlation with combined nonfatal and fatal prostate cancer cases while the correlation with state of longest residence was insignificantly reduced3. Frequent recreational sun exposure in adulthood was associated with a significantly reduced risk of fatal PCa only (RR, 0.47; 0.23-0.99)3. All other measures of sun exposure in adulthood had insignificant correlations with risk. 

A study in the Netherlands found statistically significant reduced risk of prostate cancer incidence after diagnosis of non-melanoma skin cancer for 0-1 and 2-3 years after diagnosis and insignificant reductions for 1-2 and 3-5 years after diagnosis4. However, in the table summarizing other similar studies, only one from the UK found a similar relation5.

Studies in Norway found increased survival rates for those diagnosed with PCa in summer or fall compared to winter or spring6 7.

A multi-country cohort study found that a diagnosis of either basal cell carcinoma or squamous cell carcinoma was associated with a significant reduced risk of PCa in sunny countries (Australia, Singapore and Spain) but not in less sunny countries8. This finding was explained as showing that those living equatorward of about 35º exposed sufficient amount of skin area to produce sufficient vitamin D to reduce the risk of cancer in general, but those living at higher latitudes did not9. 

A meta-analysis provided weak evidence that men with the lowest (versus highest) sunlight exposure had an increased PCa risk [four studies, random-effects pooled RR = 1.13 (0.98 to 1.29)] and higher advanced or fatal PCa risk [six studies, random-effects pooled RR = 1.14 (0.98 to 1.33]10.

Thus, there is good evidence that solar UV irradiance reduces the risk of PCa incidence and death.

However, the geographical variation of PCa mortality rates in the United States differs from the approximately 20 other types of cancer for which vitamin D is an important risk reduction factor. Most of the vitamin D-sensitive cancers have highest mortality rates in the northeast and lowest rates in the southwest11 12; the highest rates for PCa are in the northwest and the lowest rates are in the southeast11. A comparison of the map of PCa mortality rates in the United States11 with the map of greatest ancestry by county in the United States in 200013 indicated that ethnic background played an important role in PCa risk. As a result of this observation, a multicountry ecological study was conducted that found prevalence of the ApoE4 allele and diet are the most important risk factors for PCa14. ApoE4 increases cholesterol and insulin production, and cholesterol is an important risk factor for PCa15.

In summary, there is moderate evidence that solar UVB doses are inversely correlated with prostate cancer risk.

Page last edited: 24 August 2011

References

  1. Bodiwala, D. Luscombe, C. J. French, M. E. Liu, S. Saxby, M. F. Jones, P. W. Fryer, A. A. Strange, R. C. Polymorphisms in the vitamin D receptor gene, ultraviolet radiation, and susceptibility to prostate cancer. Environ Mol Mutagen. 2004; 43 (2): 121-7.
  2. Rukin, N. J. Zeegers, M. P. Ramachandran, S. Luscombe, C. J. Liu, S. Saxby, M. Lear, J. Strange, R. C. A comparison of sunlight exposure in men with prostate cancer and basal cell carcinoma. Br J Cancer. 2007 Feb 12; 96 (3): 523-8.
  3. John, E. M. Koo, J. Schwartz, G. G. Sun exposure and prostate cancer risk: evidence for a protective effect of early-life exposure. Cancer Epidemiol Biomarkers Prev. 2007 Jun; 16 (6): 1283-6.
  4. de Vries, E. Soerjomataram, I. Houterman, S. Louwman, M. W. Coebergh, J. W. Decreased risk of prostate cancer after skin cancer diagnosis: a protective role of ultraviolet radiation?. Am J Epidemiol. 2007 Apr 15; 165 (8): 966-72.
  5. Bower CP, Lear JT, Bygrave S, Etherington D, Harvey I, Archer CB Basal cell carcinoma and risk of subsequent malignancies: A cancer registry-based study in southwest England. J Am Acad Dermatol. 2000 Jun; 42 (6): 988-91.
  6. Robsahm, T. E. Tretli, S. Dahlback, A. Moan, J. Vitamin D3 from sunlight may improve the prognosis of breast-, colon- and prostate cancer (Norway). Cancer Causes Control. 2004 Mar; 15 (2): 149-58.
  7. Lagunova, Z. Porojnicu, A. C. Dahlback, A. Berg, J. P. Beer, T. M. Moan, J. Prostate cancer survival is dependent on season of diagnosis. Prostate. 2007 Sep 1; 67 (12): 1362-70.
  8. Tuohimaa, P. Tenkanen, L. Syvala, H. Lumme, S. Hakulinen, T. Dillner, J. Hakama, M. Interaction of factors related to the metabolic syndrome and vitamin D on risk of prostate cancer. Cancer Epidemiol Biomarkers Prev. 2007 Feb; 16 (2): 302-7.
  9. Grant, W. B. The effect of solar UVB doses and vitamin D production, skin cancer action spectra, and smoking in explaining links between skin cancers and solid tumours. Eur J Cancer. 2008 Jan; 44 (1): 12-5.
  10. Gilbert, R. Metcalfe, C. Oliver, S. E. Whiteman, D. C. Bain, C. Ness, A. Donovan, J. Hamdy, F. Neal, D. E. Lane, J. A. Martin, R. M. Life course sun exposure and risk of prostate cancer: population-based nested case-control study and meta-analysis. Int J Cancer. 2009 Sep 15; 125 (6): 1414-23.
  11. Devesa, S. S. Grauman, D. J. Blot, W. J. Pennello, G. A. Hoover, R. N. Fraumeni, J. F. Jr. Atlas of Cancer Mortality in the United States, 1950-1994. NIH Publication No. 99-4564. 1999 April 17, 2010;
  12. Grant, W. B. Garland, C. F. The association of solar ultraviolet B (UVB) with reducing risk of cancer: multifactorial ecologic analysis of geographic variation in age-adjusted cancer mortality rates. Anticancer Res. 2006 Jul-Aug; 26 (4A): 2687-99.
  13. Brittingham, A. de la Cruz, G. P. Ancestry 2000. Census 2000 Brief CK2BR-35. 2004;
  14. Grant, W. B. A multicountry ecological study of risk-modifying factors for prostate cancer: apolipoprotein E epsilon4 as a risk factor and cereals as a risk reduction factor. Anticancer Res. 2010 Jan; 30 (1): 189-99.
  15. Iso, H. Ikeda, A. Inoue, M. Sato, S. Tsugane, S. Serum cholesterol levels in relation to the incidence of cancer: The JPHC Study Cohorts. Int J Cancer. 2009 Jun 19;