Editor:
     I am an avid reader of the Townsend Letter who is disappointed with the June 2002 issue with its many discussions of how to prevent cancer. In my opinion, many ideas published in that issue are just not correct, especially the notion that total dietary fat should be considered a risk factor for breast cancer. That idea has been dismissed by a large number of papers, including my own.

     A good hypothesis on the environmental links to breast cancer should satisfy the following criteria: 1. explain the differences in international mortality rates; 2. explain why adult female height by country is associated with breast cancer; 3. explain the geographic distribution of breast cancer mortality rates in the US; 4. explain why all major studies of dietary links to breast cancer have concluded that total dietary fat is not a risk factor, although some fats may be risk or risk reduction factors; 5. African Americans have a higher risk for breast cancer than Caucasian Americans. Please note that the term "environmental" risk factors means everything in one's environment, including the food we eat, the water and alcohol we drink, the air we breathe, the cigarettes we smoke, the sunlight that hits our skin, and the chemicals in the environment that we encounter through the above-mentioned pathways.

     It is my considered opinion that the primary risk factors for breast cancer mortality in the US are: a diet high in animal products, high in alcohol, low in vegetable products, low in fish. In addition, low solar UV-B radiation and/or vitamin D, especially in the northeastern states, is another risk factor. The animal products are more important in youth than in adulthood, as are vegetable products, thereby explaining the association with adult female height. Alcohol, fish, and vitamin D are important in adulthood. In support of my breast cancer statements, my January 1, 2002 paper from the journal Cancer has received widespread comment at a number of web sites. The papers cited in that paper show that dietary fat is not a risk factor for breast cancer: in international studies, it has to be considered an index of a diet high in animal products, high in alcohol, and low in fish. The 1975 paper by Armstrong and Doll did not do a multiple linear regression. I also refer you to the Atlas of Cancer Mortality at its web site: http://www3.cancer. gov/atlasplus/new.html

     As for prostate cancer, my latest work (in press) indicates that animal products, calcium and milk, and sugar are the primary risk factors, with vegetable products and especially those that are good sources of protein, such as beans, as risk reduction factors. Solar UV-B and/or vitamin D are less important than for breast cancer. The dietary risk factors seem to explain why African-American men have about twice the prostate cancer rate of white Americans – the factors are very similar to those for diabetes and coronary heart disease, and African-Americans have about twice the rates of those diseases as white Americans.

     Solar UV-B and/or vitamin D are also important risk reduction factors for a total of over a dozen types of cancer. The UV-B/vitamin D hypothesis has been in the literature since at least 1980 with the pioneering work of Cedric Garland and coworkers.

     In support of my UV-B/vitamin D hypothesis, I cite my March 15, 2002 paper from Cancer. In addition, I refer you again to the Atlas and to the web site where I obtained the UV-B data I used: http://toms.gsfc. nasa.gov/ery_uv/dna_exp.gif. I also refer you to the recent paper: Freedman DM, 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. The abstract is available at PubMed, as are many more on the topic: http://www.ncbi.nlm.nih.gov/entrez/query.fcgi. Also, you might be interested to know that the number of people who die from melanoma and other skin cancer in the US due to too much UV radiation is far less than the number who die from other cancers due to insufficient UV-B radiation.

     I am in the process of extending the UV-B analyses. For breast cancer, I find that the fraction of Caucasian Americans considered Hispanic explains 1/3 as much as does UV-B radiation, and those living below the poverty level explains 15% as much as does UV-B, but neither additional factor detracts from the finding reported in the Cancer paper. I am making similar findings for many other cancers, and adding smoking and the associated diet as an additional factor for a number of cancers. I expect to submit a manuscript for publication to a peer-reviewed journal in the near future.

     Even though papers and letters published in the Townsend Letter are not peer-reviewed, I think it important for the authors to do a careful search of the literature at PubMed and consider both the supporting and opposing findings. Also, I consider it important to show that both mechanisms exist linking a proposed agent with the disease and that there are geographically distributed data that support the hypothesis. I hesitated on the vitamin D hypothesis for 8 years before I found a US Department of Agriculture report showing that there is not a factor of 2 difference in fat consumption between New England states and the southwest desert states – it is ~l0%, the same as the difference for any other macro- or micro-nutrients in our national diet.

     I would welcome a spirited debate on my findings, either in print or in personal letters.

William B. Grant, PhD
12 Sir Francis Wyatt Place
Newport News, Virginia 23606-3660 USA

Email: wbgrant@infi. net

References

1.  Grant W.B. An estimate of premature cancer mortality in the US due to inadequate doses of solar ultraviolet-B radiation. Cancer 2002, 94(6): 1867-1875.

2.  Grant W.B. An ecologic study of dietary and solor ultraviolet-B links to breast carcinoma mortality rates. Cancer 2002,94(1):272-281.