Background/Purpose: Postmenopausal women with breast cancer have higher osteoporosis risk due to declining estrogen levels and use of aromatase inhibitors (AIs). The American Society of Clinical Oncology (ASCO) update on bone health management in breast cancer elaborated on measures medical oncologists can undertake. Factors conferring high fracture risk are age ≥65, women aged 60-64 with family history of fracture, weight <70kg, prior fragility fracture, postmenopausal state on AIs, and chemotherapy (CT)-induced menopause. Recommendations include annual DXA, calcium and vitamin D for high risk patients, bisphosphonates for patients with T score ≤-2.5. Malignancies such as breast cancer are co-morbidities that rheumatic disease patients are at risk for. The purpose of this IRB-approved Loma Linda University study was to evaluate adherence of oncologists to ASCO guidelines, and to determine fracture rates in our cohort of breast cancer patients on AIs. This is a pilot study examining the practice of one of our breast cancer specialists.

Methods: Oncology clinic data from January-December 2016 was extracted using ICD10 codes related to breast cancer, osteoporosis, osteopenia, which identified 208 encounters. ICD10 code related to use of aromatase inhibitors was applied, resulting in a unique subset of 32 patients. Chart review collected patient demographics (age, sex), presence of metastases, estrogen receptor positivity (ER+), AI used, T-score (by DXA), frequency DXA ordered, anatomic fracture location, re-fracture events, bisphosphonate use, calcium/vitamin D use, current alcohol and tobacco, and thyroid disease.

Results: All 32 patients were ER+, postmenopausal females, with one having CT-induced menopause. Mean age was 70.2. Mean BMI was 26.5. 5 (16%) had thyroid disease. Twelve (39%) reported alcohol use; 1 (3%) was a smoker. Twelve (38%) of patients were on Anastrozole, 3 (9.4%) on Exemestane and 17 (53%) on Letrozole. Based on T-scores, 9 (28%) were osteopenic and 22 (69%) were osteoporotic. Twenty-nine (90%) patients were on appropriate doses of calcium/vitamin D. DXA was obtained annually in 15 (47%) patients. Of those with osteoporosis based on T-score, 17 (77%) were on a bisphosphonate, while 4 (18%) were on denosumab; 1 refused treatment. Overall, 9 fractures occurred; of these, 3 were re-fracture events. Mean age at time of first fracture was 69.3, while mean age at re-fracture was 76.3. Four (44%) occurred in the spine, with 1 due to metastases. Other sites of fracture were: hip (1), hand (1), rib (1), humerus (2). Re-fractures in the spine (2) and hand (1). Six fractures occurred while on bisphosphonates: alendronate (1), risedronate (3), ibandronate (2).

Conclusion: There was great adherence to ASCO bone health guidelines for breast cancer patients on AIs. It would be of interest if the same level of adherence applies to the entire oncology team. We also raise questions about the applicability of fracture risk calculators for this population. Postmenopausal breast cancer patients on AIs may need closer bone health monitoring given their high risk of fracture. Bone health issues related to malignancy should be of concern to all rheumatologists.

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ACR Meeting Abstracts - https://acrabstracts.org/abstract/postmenopausal-breast-cancer-patients-on-aromatase-inhibitor-therapy-and-their-increased-risk-of-fragility-fracture/