RAD50 and cholangiocarcinoma: We analyzed the publicly available TCGA database available on the cBioportal site (cbioportal.org, accessed on 25 April 2021) to identify the mutations in a panel of DDR genes (ARID1A, ARID1B, ATM, ATR, ATRX, BAP1, BARD1, BLM, BRCA1, BRCA2, BRIP1, CHEK2, FANCA/C/D2/E/F/G/L, MRE11, NBN, PALB2, RAD50, RAD51, RAD51B/C and WRN) in CCA samples (n = 195).