Volunteers sought for study of bone loss in breast-cancer patients

Women with estrogen-responsive breast cancer often are prescribed a drug that reduces their estrogen levels. But because estrogen is important to bone health, there is widespread concern about how the drugs, called aromatase inhibitors, affect bones.

A School of Medicine study investigating bone loss in women who take aromatase inhibitors is seeking volunteers.

Reina Villareal
Reina Villareal

Aromatase is an enzyme that transforms testosterone and other androgens into estrogen. This transformation represents the major, if not only, source of estrogen in postmenopausal women.

So giving women aromatase inhibitors can result in a near shutdown of estrogen production, which can have unwanted side effects.

“There are reports of an increased incidence of fractures in women on aromatase inhibitors,” said Reina Armamento-Villareal, M.D., assistant professor of medicine in the Division of Bone and Mineral Diseases and a bone specialist at Barnes-Jewish Hospital. “But studies show that women respond differently to these drugs, possibly because of variations in the gene that produces the aromatase enzyme.”

Scientists have identified several variations of that gene, called CYP19, that can result in either increased or decreased aromatase activity. This influences how aromatase inhibitors affect estrogen levels.

The study will analyze the sequence of the CYP19 gene in volunteers to see which variation they possess.

“Our hypothesis is that using aromatase inhibitors can be associated with significant bone loss, and the degree of bone loss will be related to the variations of the CYP19 gene,” Villareal said.

Data collected from the study will aid in establishing the appropriate method of maintaining bone health in women who are given aromatase inhibitors.

“As more breast-cancer patients use these drugs, more may be expected to experience osteoporotic [porous bone] complications,” Villareal said. “We want to identify those who would need early intervention to prevent bone loss with aromatase-inhibitor therapy.”

Postmenopausal women with breast cancer are eligible to participate. The researchers will compare bone loss in women taking aromatase inhibitors with those not using these drugs, so both groups are wanted for the study.

Participants will receive free bone-density scans and will be tested for blood markers that indicate bone turnover. Each volunteer will be genotyped for CYP19 variants to investigate any link between genetic profile and bone loss.

Women interested in taking part in the study or physicians referring patients for the study can call Villareal or Nicola Napoli, M.D., at 454-8437.