Bone health and adherence to vitamin D and calcium therapy in early breast cancer patients on endocrine therapy with aromatase inhibitors

Objectives Randomized trials involving aromatase inhibitors (AIs) in the adjuvant treatment of breast cancer patients have reported increased osteoporosis risk. Bone loss can be reduced with appropriate life style, vitamin D and calcium supplements, and with bisphosphonate therapy. The aim of this analysis was to investigate adherence to vitamin D and calcium in postmenopausal breast cancer patients receiving adjuvant non-steroidal AIs, and oncologists' adherence to the bone health guidelines. Material and methods This prospective study included 438 newly diagnosed patients and those who have already been receiving non-steroidal AIs for up to 3.5 years. Median endocrine therapy duration before recruitment in the study was 10.5 months (interquartile 4.8–26.6). Results Densitometry was performed on 142 patients (32.4%) before initiation of endocrine therapy, and on additional 38 (8.6%) patients at second study visit. Densitometry was not performed on 258 (59%) patients. Vitamin D and calcium were prescribed to 329/438 (75.1%) patients at some point during the study. Patients who took more than 80% of the prescribed dose were considered adherent. Self-reported adherence was 88.4%. Osteoporosis was diagnosed in 24 patients (5.5%) of the total study population, bearing in mind that 258/438 (59%) patients did not have densitometry. Bisphosphonates were prescribed to 54/438 (12.3%) patients, whilst only 19 (35.2%) of those had osteoporosis. Conclusion In this analysis, lack of oncologists' adherence to the bone health guidelines was observed. In addition, a significant proportion of the patients did not adhere to the vitamin D and calcium.