SMAD4 and cholangiocarcinoma: A large-scale genomic analysis of tumor samples from 1 104 patients with advanced CCA identified TP53 (38.1%), CDKN2A/B (28.8%), KRAS (21.9%), ARID1A (15.7%), SMAD4 (11.3%), BAP1 (10.6%), IDH1 (10.5%), PBRM1 (10.0%), FGFR2 (9.4%), ERBB2 (7.6%), PIK3CA (7.0%), MDM2/FRS2 (5.8%), and BRAF (4.7%) as the most frequently altered genes [121].