Pos0493 prevalence and incidence of osteoporotic vertebral fracture in non small cell lung cancer: analysis of a 289 patients cohort

Background The recent use of targeted therapies and immunotherapy has considerably improved the survival of patients with Non-Small Cell Lung Cancer (NSCLC), in particular metastatic ones. In this new era, it is relevant to look at the comorbidities affecting the quality of life and potentially the prognosis of NSCLC. Due to shared risk factors (tobacco, corticosteroid therapy, radiotherapy); osteoporosis is a comorbidity of interest in the context of NSCLC. Objectives The aim of our study was to establish the prevalence and incidence of osteoporotic vertebral fractures (OVF), the risk factors for incident OFV, and impact on survival of incident OFV. Methods This retrospective observational single-center study was conducted in the thoracic oncology clinic (Bichat University Hospital, AP-HP Paris, France), between January 2021 and July 2021. Consecutive patients followed for NSCLC were included in this study. The following data were collected (a) demographic characteristics such as gender, age, height and weight, BMI, smoking status, alcool intake (b) NSCLC characteristics such as histology, date of biopsy that resulted in the diagnostic of NSCLC, cancer stage (absence or presence of metastasis, including bone metastasis). Treatments received were collected a) oral corticosteroids (10 mg or more per day of prednisone or equivalent, for at least 2 weeks, in the last 2 years) b) anti-resorptive therapy (bisphosphonate, denosumab) c) local or systemic cancer treatment (surgery, radiotherapy, immunotherapy, chemotherapy and/or target treatment). We defined inclusion by the first thoraco-abominopelvic CT performed for the NSCLC extension assessment at diagnosis. We defined end of follow-up by the last TAP-CT available. We proceed to a double-blind lecture of TAP CT (rheumatologist and radiologist) to evaluate the presence of vertebral fracture: prevalent or incident, its nature (osteoporotic or metastatic), the number and localization. We also measure CT attenuation (Hounsfield unit [HU]) value of L1. Survival was assessed as of August 26, 2022. Results We included 289 patients: 162 males (56%), mean age 66.4years old. Eightt-two percent of patients were current or past smokers (42 ± 22 number of year smoking) and 22% consumed alcohol regularly. The mean BMI was 24.7 ± 5.0 kg/m². Seventy-eight percent had an adenocarcinoma and 18% a squamous cell carcinoma. Sixty one percent of patients had a metastatic cancer, including 25% of bone metastatsis. The mean follow-up time was 36.3 ± 29.4 months. At inclusion, 31 of the 289 had an OFV, for 40 OFV (24 thoracic, 16 lumbar, mean 1.3 ± 0.6 OFV per patient). The prevalence at inclusion was therefore 10.7%. At end of follow-up, 23.2% of patients (67/289) had an OVF. During the follow up of 36 ± 29 months: 36 patients had an incident OFV. The incidence of OVF was 12.5%. Ninety-seven OFV occurred (68 thoracic, 29 lumbar). Median time to incident OVF was 13 months [6.7; 21.2]. In univariate analysis (Table 1), the risk factor of OVF were: age (p=0.036), BMI <19kg/m² (p <0.01), steroid use (p<0.001), and radiotherapy (p = 0.036), UH in L1 at inclusion (HR 0.986, p <0.001) In multivariate analysis, BMI <19kg/m² (p=0.01), steroid use (p<0.001), HU in L1 at inclusion ((HR adjusted: 0,985, p = 0.003) were independent risk factor of incident OVF. Median survival was 80 months in the incident OVF group and was not reached in the patients without incident OVF (p =0.074, Image 1). Conclusion In our population, prevalence of OVF at inclusion was 10.7%. Incidence was 12.5% during a mean follow up of 36 months. Occurrence of a new OVF may have an impact on survival. Presence of OVF and UH in L1 should be evaluated systematically during NSCLC follow up. We should pay more attention to this population, in order to prescribe preventive anti-resorptive drugs if needed. Table 1. characteristics of patient with and without osteoporotic vertebral fracture (OVF). Image 1. The Kaplan-Meier probability of survival for patient with or without incident osteoporotic vertebral fracture (OVF). REFERENCES: NIL. Acknowledgements: NIL. Disclosure of Interests Esther Ebstein Consultant of: BMS - Abbvie - Galapagos, Pauline Brocard: None declared, Ghassen Soussi: None declared, Ralph Khoury: None declared, Antoine Khalil: None declared, Marine Forien Consultant of: Abbvie - BMS, Sebastien Ottaviani Consultant of: Abbvie - BMS - UCB, Gerard Zalcman: None declared, Philippe Dieudé Consultant of: Pfizer - BMS - Abbvie - UCB, Valerie Gounant: None declared.