Bladder cancerExposure to sunlight

Strong inverse correlations between solar UVB and many bladder cancer have been found in numerous ecological studies in the United States1234 and China5.

The United States is a particularly useful country to conduct ecological studies since dietary factors are largely shared and solar ultraviolet-B (UVB) doses in summer are asymmetrical, being much higher in the west than the east at the same latitude due to higher surface elevation and thinner stratospheric ozone layer, thus permitting use of an index other than latitude, which could have other bases such as temperature.  

Solar UVB in summer can increase serum 25(OH)D levels by 40 nmol/L (16 ng/ml) according to a study of 45-year old residents of the UK6, and, thus, higher amounts in the United States.  Most of the recent ecological studies used indices for other risk-modifying factors such as alcohol consumption, smoking, Hispanic heritage, poverty and urban/rural residence4.  

Another ecological study in the United States found direct correlations with smoking and drinking surface water in addition to inverse correlation with solar UVB2; the likely reason for the link to surface water was production of chlorinated hydrocarbons when chlorinating the water7.  

The study in China used UVB doses determined by the NASA satellite instrument, Total Ozone Mapping Spectrometer, and adjusted for urban/rural residence.  

A 174-country ecological study found bladder cancer incidence inversely correlated with modeled UVB doses and per capita health care expenditures and directly correlated with cigarette smoking8.  Thus, such studies largely overcome the concern regarding confounding factors.

Page last edited: 22 August 2011

References

  1. Boscoe, F. P. Schymura, M. J. Solar ultraviolet-B exposure and cancer incidence and mortality in the United States, 1993-2002. BMC Cancer. 2006; 6264.
  2. Colli, J. L. Kolettis, P. N. Bladder cancer incidence and mortality rates compared to ecologic factors among states in America. Int Urol Nephrol. 2009 Oct 7;
  3. Grant, W. B. Air pollution in relation to U.S. cancer mortality rates: an ecological study; likely role of carbonaceous aerosols and polycyclic aromatic hydrocarbons. Anticancer Res. 2009 Sep; 29 (9): 3537-45.
  4. 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.
  5. Chen, W. Clements, M. Rahman, B. Zhang, S. Qiao, Y. Armstrong, B. K. Relationship between cancer mortality/incidence and ambient ultraviolet B irradiance in China. Cancer Causes Control. 2010 Jun 16;
  6. Hyppönen, E. Power, C. Hypovitaminosis D in British adults at age 45 y: nationwide cohort study of dietary and lifestyle predictors. Am J Clin Nutr. 2007 Mar; 85 (3): 860-8.
  7. Morris, R. D. Audet, A. M. Angelillo, I. F. Chalmers, T. C. Mosteller, F. Chlorination, chlorination by-products, and cancer: a meta-analysis. Am J Public Health. 1992 Jul; 82 (7): 955-63.
  8. Mohr, S. B. Garland, C. F. Gorham, E. D. Grant, W. B. Garland, F. C. Ultraviolet B irradiance and incidence rates of bladder cancer in 174 countries. Am J Prev Med. 2010 Mar; 38 (3): 296-302.