Ten-year follow-up of 3 years of oral adjuvant clodronate therapy shows significant prevention of osteoporosis in early-stage breast cancer

Purpose We have previously reported that 3-year adjuvant clodronate treatment prevents bone loss in breast cancer patients. Here we report the 10-year follow-up data of clodronate in the prevention of treatment-related osteoporosis in women with early-stage breast cancer. Patients and Methods Two hundred sixty-eight pre- and postmenopausal, node-positive breast cancer patients were randomly assigned to clodronate, 1.6 g orally administered daily, or to control groups for 3 years. Premenopausal women were treated with adjuvant CMF chemotherapy; and postmenopausal women were treated with antiestrogens, either 20 mg tamoxifen or 60 mg toremifene, for 3 years. The bone mineral density (BMD) of the lumbar spine and hip was measured before treatment and at 1, 2, 3, 5, and 10 years after therapy. Results Eighty-nine disease-free patients were included in the analyses of osteoporosis-free survival. During the 10-year period, 24 of 89 patients were diagnosed with osteoporosis. Fourteen patients developed spinal osteoporosis (three of 41 in the clodronate group, and 11 of 48 in the control group), and 14 of 89 patients were diagnosed with hip osteoporosis (seven of 41 in the clodronate group, and seven of 48 in the control group). The 10-year spinal, osteoporosis-free survival rate was 92.7% in the clodronate group, and 77.0% in the control group (P = .035). No difference was seen in the frequency of hip osteoporosis (85.4% v 82.9%; P = .92). Baseline BMD measurement had a predictive value of 18 of 24 patients (75%) who developed osteoporosis had osteopenia of the lumbar spine at baseline. Conclusion Three years of clodronate therapy significantly reduces the incidence of lumbar spine osteoporosis. Patients at risk of developing osteoporosis are among those who have pretreatment osteopenia, that is, baseline BMD measurement has predictive value.