Inspection of the geographical variation of leukemia mortality rate in the United States1 indicates that the pattern found for most vitamin D-sensitive cancers, highest rates in the northeast, lowest in the southwest, is not the pattern for leukemia. Instead, the highest mortality rates are in the middle third going from east to west. However, the lowest rates are in the southwest. The likely reason for this pattern is the effect of agricultural pesticides on risk of leukemia2 34.
One paper reported a decrease of leukemia mortality rate with increasing altitude of residence for altitudes above 2000 feet:
From published demographic data and leukemia mortality data, the leukemia mortality rate per 100,000 population/yr was correlated with altitude. The findings of this study indicate that the leukemia mortality rate increases with increasing altitude up to about 2000 ft elevation, but that above 2000 ft the leukemia mortality rate decreases significantly with increasing altitude5.
However, looking at the Atlas of Cancer Mortality in the United States1, this could be an effect related to pesticide use in lower-altitude regions rather than a beneficial effect of solar UVB irradiance.
Childhood Acute lymphoblastic leukemia (ALL) was found to have an excess rate of about 50% for those born in winter/spring compared to summer/fall in Denmark6. It was suggested that the reason for seasonality could be maternal infection during pregnancy, giving the developing fetus exposure to the infection agent. Influenza infection rates are highest in winter due, in part, to lower solar UVB doses in winter7 8.
Month of diagnosis of 7,423 cases of AL in Finland during 1964-2003 were linked with data on influenza and solar radiation. AML showed the highest risk in the dark season. During the light season, the incidence decreased by 58% (95% confidence interval, 16-79%) per 1,000 kJ/m(2)/d increase of solar radiation. Independent of solar radiation, AML increased by 9% (95% confidence interval, 0-19%) during influenza epidemics. Reoccurring at the same time annually, darkness-related vitamin D deficiency and influenza could cause successive and co-operative mutations leading to AL with a short latency 10.
Childhood leukemia has been linked to infections in winter in the UK11.
A study in the United Arab Emirates (UAE) found a higher rate of acute lymphoblastic leukemia (ALL) among native females than native males, which is the opposite of what is found in other countries, suggesting that low serum 25(OH)D levels among females due to covering more of the skin while in the sun14.
An ecological study in China found an inverse correlation between annual solar UVB doses and leukemia incidence and mortality rates in rural regions, but an increased risk in urban regions15. Those living in rural regions are much more likely to spend significant time out of doors, possibly by working in agriculture.Thus this study provides evidence of a beneficial effect of UVB irradiance in reducing the risk of leukemia.
Based on the totality of the evidence, there is modest evidence that higher solar UVB doses are associated with lower risk of leukemia.
Page last edited: 22 August 2011
- 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;
- Beane Freeman, L. E. Bonner, M. R. Blair, A. Hoppin, J. A. Sandler, D. P. Lubin, J. H. Dosemeci, M. Lynch, C. F. Knott, C. Alavanja, M. C. Cancer incidence among male pesticide applicators in the Agricultural Health Study cohort exposed to diazinon. Am J Epidemiol. 2005 Dec 1; 162 (11): 1070-9.
- Blair, A. Zheng, T. Linos, A. Stewart, P. A. Zhang, Y. W. Cantor, K. P. Occupation and leukemia: a population-based case-control study in Iowa and Minnesota. Am J Ind Med. 2001 Jul; 40 (1): 3-14.
- Clavel, J. Hemon, D. Mandereau, L. Delemotte, B. Severin, F. Flandrin, G. Farming, pesticide use and hairy-cell leukemia. Scand J Work Environ Health. 1996 Aug; 22 (4): 285-93.
- Eckhoff, N. D. Shultis, J. K. Clack, R. W. Ramer, E. R. Correlation of leukemia mortality rates with altitude in the United States. Health Phys. 1974 Oct; 27 (4): 377-80.
- Sorensen, H. T. Pedersen, L. Olsen, J. Rothman, K. Seasonal variation in month of birth and diagnosis of early childhood acute lymphoblastic leukemia. JAMA. 2001 Jan 10; 285 (2): 168-9.
- Cannell, J. J. Vieth, R. Umhau, J. C. Holick, M. F. Grant, W. B. Madronich, S. Garland, C. F. Giovannucci, E. Epidemic influenza and vitamin D. Epidemiol Infect. 2006 Dec; 134 (6): 1129-40.
- Cannell, J. J. Zasloff, M. Garland, C. F. Scragg, R. Giovannucci, E. On the epidemiology of influenza. Virol J. 2008; 529.
- Timonen, T. T. A hypothesis concerning deficiency of sunlight, cold temperature, and influenza epidemics associated with the onset of acute lymphoblastic leukemia in northern Finland. Ann Hematol. 1999 Sep; 78 (9): 408-14.
- Timonen, T. Nayha, S. Koskela, T. Pukkala, E. Are sunlight deprivation and influenza epidemics associated with the onset of acute leukemia?. Haematologica. 2007 Nov; 92 (11): 1553-6.
- Kroll, M. E. Draper, G. J. Stiller, C. A. Murphy, M. F. Childhood leukemia incidence in Britain, 1974-2000: time trends and possible relation to influenza epidemics. J Natl Cancer Inst. 2006 Mar 15; 98 (6): 417-20.
- Gao, F. Nordin, P. Krantz, I. Chia, K. S. Machin, D. Variation in the seasonal diagnosis of acute lymphoblastic leukemia: evidence from Singapore, the United States, and Sweden. American journal of epidemiology. 2005 Oct 15; 162 (8): 753-63.
- Gao, F. Chia, K. S. Machin, D. On the evidence for seasonal variation in the onset of acute lymphoblastic leukemia (ALL). Leukemia research. 2007 Oct; 31 (10): 1327-38.
- Hassan, I. B. Islam, S. I. Alizadeh, H. Kristensen, J. Kambal, A. Sonday, S. Bernseen, R. M. Acute leukemia among the adult population of United Arab Emirates: an epidemiological study. Leuk Lymphoma. 2009 Jul; 50 (7): 1138-47.
- 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.