SAT0468 EFFECTS OF ANDROGEN DEPRIVATION THERAPY ON BONE QUALITY (TBS) IN PATIENTS WITH PROSTATE CANCER

Background: Androgen deprivation therapy (ADT), by inducing severe hypogonadism, leads to a loss of bone mineral density (BMD) and an increased risk of fragility fractures after 6 months of treatment in men with prostate cancer1. However, its effect on bone quality has not been described. Objectives: To evaluate the changes on bone microarchitecture (bone quality) assessed by TBS (trabecular Bone Score) in male patients with prostate cancer after one year of treatment with ADT. Methods: All patients diagnosed with prostate cancer candidates for long-term ADT admitted to Urology department of Hospital Universitari Parc Tauli (reference population of 450,000 inhabitants) between April 2017 and December 2019 were included. Patients who received chemotherapy, previous hormonal therapy or specific treatment for osteoporosis in the last year or those who had a very impaired functional capacity (Barthel index Demographic, clinical and analytical data (testosterone, calcium, phosphorous, alkaline phosphatase, 25-hidroxyvitamin D, PTH) were collected in all patients. A bone densitometry (GE-Lunar Prodigy) including the measurement of lumbar spine TBS (L1-L4) using Medimaps Software was performed at baseline and at 12 months of treatment with ADT. Results: 78 patients were included. Mean age 77,9±8,3 years. The median Gleason score was 7,88±1,05. 3 patients had previous fragility fracture (one sacral fracture, one fibula and one multiple vertebral fracture). Baseline analytical values in patients were the following: testosterone11,6±74,9 nmol/L.; 25-hidroxyvitamin D 20,8±10,4 ng/ml; PTH 51,8±23,0 pg/ml; CTX 0,58±0,66. The daily calcium intake was 573±207 mg/day. According to BMD, 17 patients (21,8%) had osteoporosis before starting ADT, with the following average T-score values: lumbar spine +0,15±1,85, femoral neck -1,75±1,00, and total hip -1,19±1,16. Mean baseline TBS value of the entire cohort was 1,279±0,122. 30,5% of the patients showed very degraded microarchitecture (TBS 1,310). After one year of ADT treatment, TBS mildly worsened in this cohort, with a median value of 1,256±0,131 (p = NS). However up to 43% of patients reached highly degraded microarchitecture, 27% partially degraded and only 29,5% had a normal TBS (p = NS). Conclusion: Most patients with prostate cancer have an altered bone quality before starting ADT. After 12 months of treatment, the percentage of patients with highly degraded bone microarchitecture increases, although not significantly. More studies are needed to confirm this trend and to evaluate if these patients present more long-term fractures. References: [1]Lee R, et al. Bone 2011; 48 (1): 88-95 Disclosure of Interests: Silvia Garcia-Cirera: None declared, Enrique Casado Speakers bureau: UCB, Lilly, Amgen, Theramex, Gebro, Gedeon-Richter, Stada, Jesus Munoz: None declared, Luis Del Rio: None declared, Marta Arevalo: None declared, Menna Rusinol: None declared, Noemi Navarro: None declared, Victor Parejo: None declared, Jordi Gratacos-Masmitja Grant/research support from: a grant from Pfizzer to study implementation of multidisciplinary units to manage PSA in SPAIN, Consultant of: Pfizzer, MSD, ABBVIE, Janssen, Amgen, BMS, Novartis, Lilly, Speakers bureau: Pfizzer, MSD, ABBVIE, Janssen, Amgen, BMS, Novartis, Lilly