PIK3CA and intrahepatic cholangiocarcinoma: Both APOBEC3-associated and PIK3CA TIER1 hotspot mutations were more enriched in ICC than the non-APOBEC3 and non-PIK3CA mutations, respectively, compared to controls for each HPV type/group, particularly for HPV16-positive SCC (p = 1.5 × 10−10; OR = 76.4, 95%CI = 20–288; Table 5, Table S7).