Esophageal cancerExposure to sunlight

Most of the studies relating to sunlight exposure and risk of esophageal cancer are ecological studies conducted in the U.S.12345. However, there are also ecological studies finding reduced risk of esophageal cancer incidence and/or mortality rates in China6 [Grant, 2007], France7, and Japan8.

The two studies by Grant were based on the Atlas of Cancer Mortality Rates in the United States9. The geographical variation of esophageal cancer mortality rates in the U.S. is very similar to that for breast cancer, which has strong support as a vitamin D sensitive cancer. Rates were highest in the northeast and lowest in the south, with intermediate rates along the west coast, which has lower solar UVB doses in summer than inland due to the prevailing winds bringing in fog and clouds.

The geological variation of July solar UVB dose was used in the U.S. This index is highly asymmetrical10, being high in the Southwest and low in the Northeast due to variations in surface elevation (higher in west) and stratospheric ozone layer (thinner in west). The U.S. ecological study5 found somewhat lower inverse correlation with solar UVB doses for July than for breast, colon, and rectal cancer11. Alcohol and smoking are stronger risk factor for esophageal cancer12 than the other three types of cancer5, which may explain the different finding.

Indices for other risk modifying factors, such as smoking, alcohol consumption were also used in the United States after 2002 and dietary factors were added to the multi-country studies in order to rule out well-known cancer risk factors that might affect the geographical variation and interpretation of the results. In all of these studies, significant inverse correlations between the vitamin D indices and esophageal cancer incidence and/or mortality rate were found.

A comparison of esophageal cancer mortality rates as a function of altitude of United States counties for the period 1950-69 was reported by Amsel et al13. Counties were divided into those below 1000 feet and above 3000 feet, and counties with cities with populations greater than 100,000 inhabitants were omitted since there are few such cities at high altitudes. For males, standardized mortality rates (SMRs) varied from 0.40 (95% CI, 0.22-0.66) to 0.78 (0.70-0.87) depending on degree of industrialization, Hispanic heritage, or urban residence. For females, (SMRs) varied from 0.55 (0.22-1.13) to 0.74 (0.61-0.89). While no explanation for the finding was given, the results are consistent with higher solar UVB doses at higher altitudes. UVB doses increase by about 19% per 1000 m (3300 ft) on an annual basis in Austria14.

A significant inverse correlation of esophageal cancer mortality rates with respect to non-melanoma skin cancer (NMSC) mortality rates for males but not females was also found in an ecological study of cancer mortality rates in Spain15.

A study in Australia, Singapore and Spain found statistically insignificant reduced incidence of esophageal cancer after incidence of basal cell or squamous cell carcinoma16

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. 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.
  3. Grant, W. B. An ecological study of cancer mortality rates including indices for dietary iron and zinc. Anticancer Res. 2008 May-Jun; 28 (3B): 1955-63.
  4. 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.
  5. 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.
  6. 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 : CCC. 2010 Oct; 21 (10): 1701-9.
  7. Grant, W. B. An ecological study of cancer incidence and mortality rates in France with respect to latitude, an index for vitamin D production. Deramato-Endocrinology. 2010 April/May/June; 2 (2):
  8. Mizoue T. Ecological study of solar radiation and cancer mortality in Japan. Health Phys. 2004 Nov; 87 (5): 532-8.
  9. 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;
  10. Leffell, D. J. Brash, D. E. Sunlight and skin cancer. Sci Am. 1996 Jul; 275 (1): 52-3, 56-9.
  11. Grant, W. B. The likely role of vitamin D from solar ultraviolet-B irradiance in increasing cancer survival. Anticancer Res. 2006 Jul-Aug; 26 (4A): 2605-14.
  12. Holmes RS, Vaughan TL. Epidemiology and pathogenesis of esophageal cancer. Semin Radiat Oncol. 2007 Jan; 17 (1): 2-9.
  13. Amsel, J. Waterbor, J. W. Oler, J. Rosenwaike, I. Marshall, K. Relationship of site-specific cancer mortality rates to altitude. Carcinogenesis. 1982; 3 (5): 461-5.
  14. Blumthaler, M. Ambach, W. Rehwald, W. Solar UV-A and UV-B radiation fluxes at two Alpine stations at different altitudes. Theoretical and Applied Climatology. 1992; 46 (1): 39-44.
  15. 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.
  16. Tuohimaa, P. Pukkala, E. Scelo, G. Olsen, J. H. Brewster, D. H. Hemminki, K. Tracey, E. Weiderpass, E. Kliewer, E. V. Pompe-Kirn, V. McBride, M. L. Martos, C. Chia, K. S. Tonita, J. M. Jonasson, J. G. Boffetta, P. Brennan, P. Does solar exposure, as indicated by the non-melanoma skin cancers, protect from solid cancers: vitamin D as a possible explanation. Eur J Cancer. 2007 Jul; 43 (11): 1701-12.