WASHINGTON — Aromatase inhibitors are associated with small but significant levels of additional bone loss in osteopenic women who take the drugs for hormone-sensitive breast cancer, according to a study of 104 women.
After just 1 year of aromatase inhibitor therapy, these women lost a mean of 1.5% in bone mineral density (BMD) at the lumbar spine and 2% at the femoral neck; two of the subjects progressed from osteopenia to osteoporosis, Dr. Pamela Taxel reported in a poster session at an international symposium sponsored by the National Osteoporosis Foundation.
Expected bone loss associated with natural progression generally would be about 0.5%–1% per year, according to Dr. Taxel of the University of Connecticut Health Center, Farmington.
She and her colleagues performed a chart review of 104 women who were taking the drugs for breast cancer and were evaluated for bone health. Of these, 61 (58%) had osteopenia. The patients' mean age was 58 years; they had been on aromatase inhibitor therapy for up to 2 years. At baseline, 18% (11 patients) were taking a bisphosphonate. They were followed for an additional year.
Lumbar spine BMD measurements were available at baseline and at 1 year for 39 women. After 1 year, the women had lost a mean of 1.5% in BMD at this site; 18 women had lost more than 3%. Baseline and 1-year femoral neck BMD measurements were available for 36 women.
After 1 year, there was a mean BMD decrease of 2% at this site. Four women lost more than 3% at the spine and more than 5% at the femoral neck.
Two of the 36 women with both lumbar spine and femoral neck data progressed to osteoporosis during the follow-up period.
The progression in bone loss occurred despite increased patient compliance with vitamin D supplements. At baseline, 74% of the women were taking at least 1,000 mg/day of vitamin D, although 41% were still deficient. At the end of the follow-up period, vitamin D intake had significantly increased, with only 25% of the women still deficient, Dr. Taxel noted.