Basic Research - Cancer(구연) Oral Session1 / Basic Research - Cancer (Ⅰ) (O-007) Rm.201 10월 30일(수) 13:00-14:00 Distinct Mutation Profiles between Primary Bladder Cancers and Circulating Tumor Cells Warrant the Use of Circulating Tumors Cells as Cellular Resource for Mutation Follow-up 1Department of Urology, Seoul St. Mary’s Hospital, College of Medicine, The Catholic University of Korea, Seoul, Republic of Korea 2Department of Medical Informatics, College of Medicine, The Catholic University of Korea, Seoul, Republic of Korea 2Cancer Research Center, College of Medicine, The Catholic University of Korea, Seoul, Republic of Korea  2Department of Biomedicine & Health Sciences, Graduate School, The Catholic University of Korea, Seoul, Korea 3Cytogen Inc., Seoul, Korea Tae-Min Kim2, Jinseon Yoo2, Yong-Jun Suh3, Hyong Woo Moon1, Sungmin Kang1, Jong Hyup Yang1, Jin Bong Choi1, Sung-Hoo Hong1, Ji Youl Lee1 and *U-Syn Ha1 Purpose: While circulating tumor cells may serve as minimally invasive cancer markers for bladder cancers, the relationship between primary bladder cancers and circulating tumor cells in terms of somatic mutations is largely unknown. Materials and Methods: Bladder cancer tissue was collected by transurethral resection of the bladder and preserved by snap-freezing. Circulating tumor cells were Isolated from the blood obtained before treatment. We performed whole exome sequencing of 20 matched pairs of primary bladder cancers and circulating tumor cells to identify and compare somatic mutations of these two different genomic resources. Results: We observed that mutation abundances of primary bladder cancers and circulating tumor cells were highly variable. The mutation abundance were not significantly correlated between matched pairs. Of note, the mutation concordance between two resources was only 3 – 24% across 20 pairs examined, suggesting that the circulating tumor cell genomes of bladder cancer patients might be genetically distinct from primary bladder cancers. A relative enrichment of mutations belonging to APOBEC-related signature and a depletion of C-to-G transversions were observed for primary- and circulating tumor cells specific mutations, respectively, suggesting that distinct mutation forces might have been operative in respective lesions during carcinogenesis. Conclusions: The observed discrepancy of mutation abundance and low concordance level of mutations between genomes of primary bladder cancers and circulating tumor cells should be taken into account when evaluating clinical utility of circulating tumor cells for treatments and follow-up of bladder cancers. keywords : Bladder cancer, Circulating Tumor Cells, Mutation