Inherited vulnerability to hormones of puberty may be a cause of disease.

2003 JUL 3 - (NewsRx.com & NewsRx.net) -- Certain breast cancers may be linked to an unusual sensitivity to the hormones that flood the body at puberty - a sensitivity that appears inherited, according to preventive medicine researchers at the Keck School of Medicine of the University of Southern California.

They reported their findings in the June 5, 2003, issue of the New England Journal of Medicine (Puberty and genetic susceptibility to breast cancer: A case-control study in twins. N Engl J Med, 2003;348(23):2313-2322).

"We don't know all the causes of breast cancer, and this study provides some insights into another pathway that could lead to the discovery of additional genes that might help explain the causes of hereditary breast cancer," says study coauthor Ann S. Hamilton, PhD, assistant professor of preventive medicine at the Keck School and USC/Norris Comprehensive Cancer Center.

Hamilton and coauthor Thomas M. Mack, MD, MPH, professor of preventive medicine at the Keck School, conducted the study among 1,811 pairs of female twins, one or both of whom had breast cancer. Mack recruited both identical and fraternal twins for the study between 1980 and 1991.

He asked the twins a variety of questions about their history: age at first menstrual period, age when each twin had her first child, how many children they had, age at the beginning of menopause, and similar factors thought to be linked to breast cancer risk.

Among identical twins who both were diagnosed with breast cancer, one factor stood out: the twin who began menstruating earlier was more than five times as likely as the other twin to get breast cancer first. Women who started menstruating before age 12 were especially susceptible to getting breast cancer first within the pair.

"We think these concordant twins are the most likely to have heritable disease," Mack says.