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PAPERS: V A McCormack, I dos Santos Silva, B L De Stavola, R Mohsen, D A Leon, and H O Lithell Fetal growth and subsequent risk of breast cancer: results from long term follow up of Swedish cohort BMJ 2003; 326: 248 [Abstract] [Full text]

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The Findings of McCormack, et al., May Be Explained by Increased Testosterone

James M. Howard   (7 February 2003)

The Findings of McCormack, et al., May Be Explained by Increased Testosterone 7 February 2003
James M. Howard, independent biologist 1037 North Woolsey Avenue, Fayetteville, Arkansas 72701-2046, U.S.A. Send response to journal: Re: The Findings of McCormack, et al., May Be Explained by Increased Testosterone	It is my hypothesis that the "secular trend," the increase in size and earlier puberty currently occurring within many populations, represents an increase in percentage of individuals of higher testosterone, males and females. Subordinate to the foregoing hypothesis is my suggestion that increased testosterone exerts negative effects proportionate to the increase of these individuals. One of the consequences of increased testosterone may be increased breast cancer within women. Breast cancer is increasing. (To read the mechanism in detail please see: "An Explanation of Cancer and the Increase in Cancer" at: http://www.naples.net/~nfn03605/dheacan2.htm , 1994.) Mothers of higher testosterone are exposing their fetuses to higher levels of testosterone in utero which affects fetal growth and subsequent physiology and pathology as adults. McCormack, et al., found: "Size at birth, particularly length and head circumference, is associated with risk of breast cancer in women aged <50 years. Fetal growth rate, as measured by birth size adjusted for gestational age, rather than size at birth may be the aetiologically relevant factor in premenopausal breast cancer." I suggest exposure of female fetuses to increased testosterone stimulates growth more characteristic of males. Hence, the females in this study, who later develop breast cancer, grow faster in utero and exhibit greater size and larger head circumferences. The increased testosterone exposure in utero and later in life increases the probability of breast cancer. In 2002, testosterone, even more than estrogen, has been linked to breast cancer risk: "…testosterone might be more strongly associated with [breast cancer] risk than estradiol." (Journal of the National Cancer Institute 2002; 94: 606-616). This may explain the findings of McCormack, et al. Competing interests:   None declared