PD14-09 CIRCULATING TUMOR DNA PRIOR TO THERAPY INITIATION IN DE NOVO METASTATIC PROSTATE CANCER

METHODS: Materials and Methods: Because of the complexity of transcript regulation caused by somatically acquired alterations, germline determinants of gene expression in tumors are infrequently studied.By using the multilevel information which are published in The Cancer Genome Atlas (TCGA), We performed expression quantitative trait locus (eQTL)-based analyses.Then we did the eQTL analyses of 30 previously reported prostate cancer risk loci and pyrosequencing was used to quantify methylation in 25 candidate genes with established or suggested roles in cancer.Our analysis identified an risk loci to act through SCGB1A1.A total of 580 patients with PCa who were diagnosed with high expression of the loci, and all of them were received ADT as the primary treatment were included in the current study.Study endpoint was defined as failure to ADT, which designated sustained PSA increase from nadir.Association of demographic and clinicopathological variables such as age, T stage, Gleason score, PSA value, and PSA nadir with time to ADT failure were tested using the Cox regression model.RESULTS: Results: Our eQTL analysis identified an risk loci to act through SCGB1A1.The median time to ADT failure was 27.0 months.Stage, Gleason score, PSA nadir were significantly associated with time to ADT failure in the univariate regression analysis (All P<0.001).Gleason score was the only variable that remained statistically significant in the multivariate analysis (P¼0.001).CONCLUSIONS: Conclusions: We concluded that the patients who were diagnosed with high expression of the loci analysised by eQTL may have the worse outcome of ADT.And Gleason score, as a pathological characteristic, was statistically significantly associated with the length of ADT in different stage of PCa.