Opportunistic Evaluation and Follow-Up of Bone Mineral Density by CT for Patients Receiving Immune Checkpoint Inhibitors

Objectives Immune checkpoint inhibitors (ICIs) have revolutionized prognoses in oncology but their efficacy is often associated with immune toxicity. Few studies have investigated potential effects of immunotherapy on bones. We aimed to evaluate the bone status of patients undergoing ICI therapy. Methods In this retrospective monocentric descriptive study, we included all adult patients treated with ICIs with at least one thoracic or abdominal computed tomography scan as part of their oncological follow-up. The opportunistic diagnosis of osteoporosis was performed by determining the estimated bone mineral density (eBMD) by measuring regions of interest in the trabecular bone in T7 and L1 vertebrae in Hounsfield units (HUs). Results Between January 2014 and December 2021, 87 patients (56.3% male) were included. The main cancers were lung cancer (66.7%) and skin cancer (20.8%), with 77 patients (88.5%) at the metastatic stage, mainly treated with the PD1 inhibitors. Two measurements were for 79 patients with no significant of BMD change upon treatment after a follow-up of 16.3 ± 14.1 months. If we focused on the association between UH<110 and/or vertebral fracture, or UH<90 and/or vertebral fracture, 43 patients and 27 patients were identified using these criteria respectively. Conclusion Nearly half of the patients treated with ICIs were osteoporotic without specific treatment, despite significant risk factors for bone loss and fractures. During follow-up, BMD was stable under ICI therapy..