805P - Bone Turnover Markers and Potential Correlation with Outcomes in Patients with Genitourinary Cancer (Renal and Bladder) and Bone Metastasis (Results of the Tugamo Study)

Abstract

ABSTRACT Background Levels of bone turnover markers (BTM) might be correlated with outcome in terms of skeletal related events (SRE), disease progression and death. The aim of the study was to determine the possible correlation between BTM, disease progression, SREs and death in patients with genitourinary cancer and bone metastases (BM) treated with zoledronic acid (ZA). Methods Observational, prospective, multicenter study. Patients with genitourinary cancer (prostate, renal, bladder) and BM were included. BTM determined were: carboxiterminal telopeptide of type I collagen (β-CTX) and bone specific alkaline phosphatase (BALP) by ELISA (immunoenzymatic assay, IDS UK), and aminoterminal propeptide of type I collagen (P1NP) by automatised assays (Elecsys, Roche). All BTM were determined at baseline (V0) and every 3 mo of treatment until Month 18 (V6). All patients started treatment with ZA 4 mg IV every 3–4 weeks at the beginning of the study. Results Data of 168 patients with genitourinary cancer were analyzed. In this work data of renal (RC) (n = 39) and bladder (BC) (n = 34) cancer patients are presented. Population basal characteristics: mean age (years): 65.1 (RC) / 64.4 (BC); median time from tumor diagnosis to detection of BM (months): 6.2 (RC) / 2.4 (BC); previous SRE: 56.4% (RC) / 50% (BC). Patients with pathologic baseline levels were: 47.4% β-CTX, 59% BALP and 31% P1NP (RC) and 71.9% β-CTX, 76.5% BALP and 81.3% P1NP (BC). After 6 mo: 0%, 21.1% and 26.7% (BC) and 0%, 18.2% and 10% (RC) presented pathologic levels of β-CTX, BALP and P1NP, respectively. Normalized levels remained steady throughout 18 mo follow-up. Reductions from baseline to Month 3 in s-CTX levels correlated with lower risk of progression (p = 0.0084) and death (p = 0.0232) (RC) / and death (p = 0.0189) (BC) (Cox regression analysis). Conclusions Elevation of baseline BTM levels is frequently present in advanced genitourinary cancer with bone metastasis. Addition of ZA to standard systemic therapy reduces BTM levels. A significant association was observed between elevated levels of s-CTX and disease progression and death (renal) and death (bladder) throughout follow-up. Disclosure All authors have declared no conflicts of interest.