Researchers have found that blood hormone tests can predict a woman’s risk of postmenopausal breast cancer for up to 20 years.

The study used data from the Nurses Health Study and looked at 796 patients with postmenopausal breast cancer who had not received hormone therapy, and each was matched with two controls who were not diagnosed with breast cancer. Blood tests had been conducted on these women during the periods 1989 to 1990 and 2000 to 2002. The researchers found a single hormone level that was associated with breast cancer.

“We found that a single hormone level was associated with breast cancer risk for at least 16 to 20 years among postmenopausal women not using postmenopausal hormones,” said Dr. Xuehong Zhang, lead author of the study and instructor at Brigham and Women’s Hospital at Harvard Medical School. “We, and others, are now evaluating if the addition of hormone levels to current risk prediction models can substantially improve our ability to identify high-risk women who would benefit from enhanced screening or chemoprevention – if so, the current data suggest that hormone levels would not need to be measured in the clinic more than once every 10, or possibly 20, years.”

Zhang and colleagues also found that women with hormone levels in the highest 25% for estradiol, testosterone, and DHEAS (Dehydroepiandrosterone Sulfate) had a 50% to 107% greater chance of developing breast cancer when compared to the lowest 25%. The researchers stated that, in general, increased hormone levels except for DHEAS “tracked closely” with an increased risk for receptor-positive breast cancer, and were associated with recurrent or fatal breast cancer.

The study is to be presented at the 11th Annual American Association for Cancer Research (AACR) International Conference on Frontiers in Cancer Prevention Research.