AIs and Bone Loss
A common side effect of any of the AIs (aromatase inhibitors) is bone weakening, shrinking bone density. This is the reason that a baseline bone density test is usually ordered when you begin one of these drugs and why you continue to have the test every year or two. Fortunately, there are good treatments for this potential problem, and the important thing is awareness and responding to any bone density loss. Here is a good summary from the Annals of Oncology. Per usual, I am giving you the introduction and then a link:
Management of aromatase inhibitor-associated bone loss in postmenopausal women with breast cancer: practical guidance for prevention and treatment
P. Hadji1*, M. S. Aapro2, J. J. Body3, N. J. Bundred4, A. Brufsky5, R. E. Coleman6, M. Gnant7, T. Guise8 & A. Lipton9
Background: Bone mineral density (BMD)-based guidelines for bone-directed therapy in women with early breast cancer (EBC) appear inadequate for averting fractures, particularly during aromatase inhibitor (AI) therapy. Therefore, an algorithm was developed to better assess risk and direct treatment (Hadji P, Body JJ, Aapro MS et al. Practical guidance for the management of aromatase inhibitor-associated bone loss. Ann Oncol 2008; 19: 1407-1416). Here, we provide updated guidance on pharmacologic interventions to prevent/treat aromatase inhibitor-associated bone loss (AIBL).
Design: Systematic literature review identified recent advances in preventing/treating AIBL. Individual agents were assessed based on trial size, design, follow-up, and safety. Results: Fracture risk factors in patients with EBC remain unchanged (Hadji P, Body JJ, Aapro MS et al. Practical guidance for the management of aromatase inhibitor-associated bone loss. Ann Oncol 2008; 19: 1407-1416). The World Health Organization Fracture Risk Assessment Tool algorithm includes fracture risk factors plus BMD but does not adequately address AIBL effects. Several antiresorptives can prevent/treat AIBL. However, concerns regarding compliance and long-term efficacy/safety remain. Overall, evidence is strongest for twice-yearly zoledronic acid (ZOL), and recent advances support additional anticancer benefits from ZOL.
Conclusions: All patients initiating AIs need advice regarding exercise, calcium/vitamin D supplements, baseline BMD monitoring (when available), and bone-directed therapy if T-score <22.0 or at least two fracture risk factors were observed. Patients with T-score > 22.0 and no risk factors should be managed based on BMD loss during years 1-2. Unsatisfactory compliance/decreasing BMD after 12-24 months on oral bisphosphonates should trigger a switch to i.v. bisphosphonate.