THE PROGNOSTIC AND PREDICTIVE VALUE OF SERUM BONE BIOMARKER (CTX) IN PATIENTS WITH BREAST CANCER METASTATIC TO BONE RECEIVING ZOLEDRONIC ACID

Background: Bone metastasis in breast cancer patients can lead to the development of skeletal related events such as pathologicalfractures, cord compression, bone marrow infiltration, hypercalcemiaof mal ignancy and the need of radiotherapy or surgery to bone. Eachof these complications may substantially reduce quality of life and, insome cases, may affect the overall survival survival. The use of bone targeted agents had led to decrease of the skeletal related events, however, prognostic and predictive markers are needed to identify patients who are at greater risk of bone disease progression and development of SRE despite using bone modifying agents.Aim of the Work: The aim of this study was assessment of the prognostic and predictive role of serum bone biomarker CTX in breast cancer patients with bone metastasis.Patients and methods: Sixty five consecutive patients who have received any type of systemic treatment (chemotherapy, hormonal therapy or targeted therapy) and zoledronic acid i.v. every 4 weeks were enrolled in this prospective non randomized study. Serumβ CTX was measured at 6 month intervals and it was correlated with the clinical outcomesResults: Between March 2017 and December 2018, 65 patients with breast cancer and bone metastases were included in the study, 31 patients with bone only disease and 34 with bone and visceral metastasis. Patients with baseline serum β CTX above 122 pg/ml (the median value) had statistically significantly lower mean PFS compared to patients who had baseline β CTX equal or below 122pg /ml (9 months versus 10.5 months). Also patients with increasing β CTX during the follow up period had significantly lower PFS compared to patients with decreasing serum βCTX (7.7 months versus 11.2 months), patients who developed at least one SRE during the study period had statistically significant higher baseline serum βCTX, however the median values at 6 months and 12 months did not correlate with the occurrence of SRE.Conclusion: Baseline serum βCTX is a promising tool that can be used as a potential prognostic marker for bone disease outcome and a predictive marker for occurrence of skeletal related events in breast cancer patients with bone metastasis.