Endocrine Abstracts

Introduction: Immune check-point inhibitors (ICI) can cause adverse events in many organs due to the activation of T-cells. Data on the effect of ICI on bones and incidence of fracture is still scarce.

Aim: To quantify the rate of osteoporotic fracture before and after the use of ICI in cancer patients.

Methods: We retrospectively retrieved pertinent data of all patients who were treated with ICI between 2015 and 2023 at the Tel-Aviv Souraski Medical Center. Healthcare administrative databases were assessed for the presence of fracture diagnostic codes in the year prior to and up to two years after ICI initiation. Fracture rate was stratified based on the time-period before and after ICI initiation.

Results: The study cohort consisted of 1349 ICI users. The mean age was 67.7 (10.9) years, 58% were male, 35.5% were active smokers, 18% were diabetics, mean BMI was 25.7 (6.8) and mean Charlson Comorbidity Index was 4.2 (2.3). Most patients were treated with an anti-PD-1 agent (82.1%), for 17.6% it was the only therapy. The fracture rate in the year prior to ICI initiation was 8.9 per 1000 patient-years. The fracture rate in the year after ICI initiation was 12 per 1000 patient-years. The fracture rate in the second year after ICI initiation was 18.9 per 1000 patient-years. In the first and second years after ICI treatment initiation, incidence rates of fractures were higher compared to the last year prior ICI treatment, IRR=1.34 (95% 0.64–2.85) and IRR=2.13 (95% 1.02–4.41), respectively. Only 12.5% of the patients who sustained a fracture received an antiresorptive treatment.

Conclusions: Fracture risk may be increased in cancer patients after initiation of ICI. Prospective studies monitoring BMD in addition to fracture rate are needed. An effort should be made to identify patients at risk for fractures and offer adequate therapy.