Estrogen stimulates the growth of breast cancer tumors. AIs have gained attention in recent years as a possible alternative to tamoxifen or as a therapy that can be taken after the suggested five-year limit for taking tamoxifen dosing has elapsed. Like tamoxifen, AIs may prevent the recurrence of breast cancer in postmenopausal women who have completed chemotherapy.

AIs are associated with increased bone loss, but this study of exemestane found that there was no significant difference in bone loss from the spine and some modest loss of bone from the hip compared to the control group. Fracture rates were similar in both groups during the one-year trial.

This information may provide researchers with information on which AI will offer the most therapeutic effect while minimizing serious side effects like osteoporosis. "We need to see longer term results, but finding effective drugs with the least degree of potential side effects for the patient will continue to be an important direction of research," said Perkins.

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