Endometrial cancerExposure to sunlight

Most of the studies relating to sunlight exposure and risk of endometrial cancer are ecological studies conducted in the U.S.12345.

In all of these studies, significant inverse correlations between the vitamin D indices and endometrial cancer incidence and/or mortality rate were found.

The studies by Grant were based on the Atlas of Cancer Mortality Rates in the United States6. The geographical variation of endometrial 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. The geological variation of July solar UVB dose was used in the U.S. This index is highly asymmetrical7, being high in the southwest and low in the northeast due to variations in surface elevation and stratospheric ozone layer.

In Europe, latitude was used as the index of vitamin D8.There is also an ecological study using data from France that found significantly reduced risk of endometrial cancer with respect to increasing latitude9.

In a global multi-country study10, calculated solar UVB doses and cloud cover were used for the vitamin D index. Indices for other risk modifying factors, such as smoking, alcohol consumption were also used in the United States after the 2002 study 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. 

A study in Sweden reported a beneficial effect of UV irradiance in reducing the risk of endometrial cancer: 

Among the 17,822 postmenopausal women included, 166 cases of endometrial cancer were diagnosed. We used a multivariate Cox regression analysis adjusting for age and other selected demographic variables to determine the risk of endometrial cancer. Women using sun beds >3 times per year reduced their hazard risk (HR) by 40% (0.6, 95% confidence interval (CI) 0.4-0.9) or by 50% when adjusting for body mass index or physical activity (HR 0.5, 95% CI 0.3-0.9), and those women who were sunbathing during summer reduced their risk by 20% (HR 0.8 95% CI 0.5-1.5) compared with women who did not expose themselves to the sun or to artificial sun (i.e., sun beds)11.

Non-melanoma skin cancer (NMSC) is often an index of high personal solar UVB irradiance. Thus, it can be used as a long-term vitamin D index in sunnier countries where it is warm enough to expose sufficient skin area while in the sun to produce a reasonable amount of vitamin D.

A study in Australia, Singapore and Spain found reduced incidence of endometrial cancer after incidence of basal cell or squamous cell carcinoma, albeit statistically insignificant due to low numbers of cases12

Page last edited: 22 August 2011

References

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  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. How strong is the evidence that solar ultraviolet B and vitamin D reduce the risk of cancer?: An examination using Hill’s criteria for causality. Dermatoendocrinol. 2009 Jan; 1 (1): 17-24.
  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. 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;
  7. Leffell, D. J. Brash, D. E. Sunlight and skin cancer. Sci Am. 1996 Jul; 275 (1): 52-3, 56-9.
  8. 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.
  9. 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):
  10. Mohr, S. B. Garland, C. F. Gorham, E. D. Grant, W. B. Garland, F. C. Is ultraviolet B irradiance inversely associated with incidence rates of endometrial cancer: an ecological study of 107 countries. Prev Med. 2007 Nov; 45 (5): 327-31.
  11. Epstein, E. Lindqvist, P. G. Geppert, B. Olsson, H. A population-based cohort study on sun habits and endometrial cancer. Br J Cancer. 2009 Aug 4; 101 (3): 537-40.
  12. 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.