Abstract PS9-30: The efficacy of a comprehensive bone health program in maintaining bone mineral density in postmenopausal women with early-stage breast cancer treated with endocrine therapy

Introduction: Given the recent advances in early detection, improving access to care and the introduction of more effective anti-cancer medications including endocrine therapy, targeted and immunotherapy, more women with breast cancer survive their disease. Majority of patients with breast cancer express hormone receptors (estrogen and or progesterone receptors) on cancer cells. Aromatase inhibitors (AI) are the gold standard treatment of hormone-sensitive postmenopausal women with breast cancer. Several studies had documented the accelerated bone loss associated with AI. The use of bone modifying agents like bisphosphonates and denosumab had resulted in significant improvement in bone mineral density among females treated with AI. In this paper, we study the efficacy of implementing a comprehensive program on bone health for such patients. Patients and Methods: Postmenopausal women with hormone-sensitive early-stage breast cancer treated with endocrine therapy (ET) were included. A comprehensive bone health program was implemented. The program includes extensive counselling by medical oncologist, calcium and vitamin-D supplements, increase milk intake and exercise. Patients with baseline lumbar spine or total hip T-scores ≥ -2 were given short intravenous bisphosphonate infusion every 6 months. Patients with osteoporosis are referred to and followed in a specially designed “osteoporosis clinic”. Results: Between 2013 and 2019, a total of 210 patients fulfilled the eligibility criteria and were enrolled. All were female, median (range) age 67 (43-86) years. All patients had a pathologically confirmed diagnosis of breast cancer, treated and followed up at our institution. High risk patients (n=103, 49.0%) were treated with 6-8 cycles of chemotherapy, including anthracyclines and taxanes. Following the completion of chemotherapy, all patients were treated with endocrine therapy. Patients with low-risk disease (n=107, 51.0%) were treated with upfront endocrine therapy-alone. Aromatase inhibitors, letrozole or anastrozole, were the endocrine therapy of choice in all patients. At baseline, and prior to start of AI, the median T-scores at the hip and lumber spines were -1.0 (range: -3.6, 1.9) and -1.4 (range: -3.9, 2.6), respectively. Osteoporosis was documented in 38 (18.1%) patients while 101 (48.1%) others had osteopenia; none were on any treatment or even aware of their BMD. 46 (25.3%) patients had vitamin-D deficiency while 74 (40.7%) others had vitamin-D insufficiency and none were on prior active replacement therapy or even aware of this problem. Following at least 12-months of endocrine therapy, 32 (84.2%) of patients with osteoporosis and 69 (68.3%) of those with osteopenia had a stable or higher BMD. Thus, the number of patients with osteoporosis declined to 27, 12.9% of the total cohort. On the other hand, 41 (57.7%) of those with normal baseline BMD had a drop in their follow up BMD. Vertebral fractures, presented with back pain and documented by imaging studies, were reported in 3 (11.1%) patients with osteoporosis compared to none in patients with normal BMD, p=0.021. Rib fracture and hip fracture were reported in one patient each and both had normal BMD before and after AI therapy. Conclusions: Postmenopausal women with breast cancer are at risk of osteopenia and osteoporosis. Such risk increases significantly with the use of AI. However, early interventions with modifiable risk factors, Vitamin-D supplements and use of bone-modifying agents can lower this risk. Citation Format: Razan Mansour, Ula Al-Rasheed, Akram Al-Ibraheem, Shereen Abu Jaradeh, Rashid Abdel-Razeq, Rayan Bater, Noor Mashahdani, Shrouq Tbayshat, Hikmat Abdel-Razeq. The efficacy of a comprehensive bone health program in maintaining bone mineral density in postmenopausal women with early-stage breast cancer treated with endocrine therapy [abstract]. In: Proceedings of the 2020 San Antonio Breast Cancer Virtual Symposium; 2020 Dec 8-11; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2021;81(4 Suppl):Abstract nr PS9-30.