Colorectal cancerExposure to sunlight

Lower rates of colorectal cancer are seen in areas that have more sunlight 

Strong inverse correlations between solar UVB and colorectal cancer have been found in numerous ecological studies in the United States1 2 3 4 5 6.

The more recent studies included a number of other risk-modifying factors in the analysis including alcohol consumption, smoking, and urban/rural residence.

In Japan, there was an increase in colorectal cancer with decreasing annual solar radiation7.

In Spain, non-melanoma skin cancer mortality rate, an index of lifetime solar UVB irradiance, was significantly inversely correlated with colon and rectal cancer for both males and females; however, latitude was inversely correlated only with rectal cancer8.

Note that ecological studies integrate the effect of solar UVB and vitamin D throughout the entire lifetime.

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. Freedman, D. M. Dosemeci, M. McGlynn, K. Sunlight and mortality from breast, ovarian, colon, prostate, and non-melanoma skin cancer: a composite death certificate based case-control study. Occup Environ Med. 2002 Apr; 59 (4): 257-62.
  3. Garland, C. F. Garland, F. C. Do sunlight and vitamin D reduce the likelihood of colon cancer?. Int J Epidemiol. 1980 Sep; 9 (3): 227-31.
  4. Grant, W. B. An estimate of premature cancer mortality in the U.S. due to inadequate doses of solar ultraviolet-B radiation. Cancer. 2002 Mar 15; 94 (6): 1867-75.
  5. Grant, W. B. Lower vitamin-D production from solar ultraviolet-B irradiance may explain some differences in cancer survival rates. J Natl Med Assoc. 2006 Mar; 98 (3): 357-64.
  6. 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.
  7. Mizoue, T. Ecological study of solar radiation and cancer mortality in Japan. Health Phys. 2004 Nov; 87 (5): 532-8.
  8. Grant, W. B. An ecologic study of cancer mortality rates in Spain with respect to indices of solar UVB irradiance and smoking. Int J Cancer. 2007 Mar 1; 120 (5): 1123-8.