Keck School scientists obtained mammograms on more than 200 women and found that those with a genetic variant developed denser breast tissue after using estrogen and progestin therapy than women without the variant.

Mammographic density is a risk factor for breast cancer and has been proposed as a marker for breast cancer risk.

"Our research is promising. We already know that only some women who use hormone replacement therapy with estrogen and progestin go on to develop breast cancer," says Giske Ursin, M.D., Ph.D., associate professor of preventive medicine at the Keck School and one of the study authors. "If we could have a way of picking out the subset of women who are at risk for breast cancer from using standard hormone replacement therapy, we could offer these women some other treatment for their postmenopausal complaints."

The researchers presented their findings at a meeting called "SNPs, Haplotype, and Cancer: Application in Molecular Epidemiology," sponsored by the American Association for Cancer Research. SNPs is scientific shorthand for single nucleotide polymorphisms, which refer to differences in specific genes within the human genome.

Researchers explain that 99.9 percent of the genome is identical in all humans. But the rest of the genome is where it gets interesting--and where SNPs can be found. These polymorphisms are bits of the genetic blueprint that exist in different varieties within the population. They may account for characteristics as obvious as hair color or as complicated as the body's ability to break down hormones.

In their study, Keck School researchers aimed to find out which polymorphisms might link female hormones to increased b
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Contact: Warren Froelich
froelich@aacr.org
215-440-9300
American Association for Cancer Research
12-Sep-2003