Risk factors for fractures in patients on hormonal therapies for breast cancer and DCIS.

Abstract

e19627 Background: Hormonal therapy with aromatase inhibitors (AI) or tamoxifen (TAM) is standard of care for hormone receptor positive breast cancer and DCIS. Fractures are a complication of treatment with AI due to accelerated bone loss. Risk factors for fracture in patients on hormonal therapy (HT) for breast cancer and DCIS are poorly defined. Methods: All 71 patients with breast cancer or DCIS seen in the bone and mineral clinic of our institution from 2000 to 2010 were analyzed. Data on demographics, pathology, type and duration of HT, bone mineral density studies (BMD), number and site of fractures were collected. Statistical analysis: t test, chi square test and Fisher’s exact test for categorical data. Results: The age of the patients ranged 40 to 97 years. 65 patients had ER positive breast cancer, 6 patients had DCIS. 9 patients had fractures.41 patients were on an AI alone, 8 were on TAM alone and 14 were on both sequentially. Fractures involved: vertebral compression, femur, hip, distal radioulnar, rib, hand and feet bones. Patients who had osteoporosis at the femur, osteoporosis or osteopenia in the lumbar spine or forearm in the initial BMD study were found to have an increased risk of fracture (P<0.05). Patients who were on TAM and AI sequentially had an increased risk of fracture (P<0.05) compared AI alone. The use of bisphosphonates and the duration of use were significantly associated with fracture (P<0.05) as these patients already had osteoporosis. The age, race, duration of AI use and the use of calcium and vitamin D were not found to be significantly different in patients who had fractures compared to those who did not. In the 24 patients who had two BMD studies, there was no significant change in the BMD overall. Conclusions: Patients with osteoporosis or osteopenia at baseline have an increased risk of fracture with the use of hormonal therapies for breast cancer and DCIS. This risk was not eliminated by the use of bisphosphonates. Sequential use of tamoxifen and aromatase inhibitors increase the risk of fractures. Bone mineral density studies done prior to the initiation of hormonal therapy for breast cancer maybe useful estimating the risk of fracture while on treatment.