Hereditary breast cancer related to timing of puberty

Lifetime hormone exposure is thought to influence the risk of sporadic breast cancer. In contrast, most cases of hereditary breast cancer do not appear to be related to such exposure, but are associated with the timing of puberty and “result from an unusual sensitivity to pubertal hormones,” according to a new report.

The findings, published in the June 5th issue of The New England Journal of Medicine, are based on a study of 1811 pairs of female twins in which one or both had breast cancer. Breast cancer that occurred in both twins of a monozygotic pair was assumed to be hereditary, while cancer that occurred in only one member was assumed to be sporadic.In monozygotic twins who both had breast cancer, “the twin with earlier puberty was diagnosed with the malignancy first,” lead author Dr. Ann S. Hamilton, from the University of Southern California in Los Angeles, told Reuters Health. Parity and age at menopause, factors that relate to cumulative hormone exposure, were not associated with age at diagnosis, she added.”In our other patient groups, we did find an effect for cumulative exposure,” Dr. Hamilton said. In these patients, later first pregnancy, lower parity, and later menopause were all associated with an increased risk of breast cancer, she added.Future research on hereditary breast cancer should focus on “genetic factors that might enhance the sensitivity of immature breast cells” to malignant transformation, Dr. Hamilton suggested.In a related editorial, Dr. Patricia Hartge, from the National Cancer Institute in Rockville, Maryland, writes that “as studies succeed in finding gene-hormone interactions, we can expect to illuminate the pathways to breast cancer and to reduce the chances that it will develop.”(Source: N Engl J Med 2003;348:2313-2322,2352-2354: Reuters Health: Anthony J. Brown, MD: June 5, 2003: Oncolink)