H2BC21 and head and neck squamous cell carcinoma: Prior studies reported (45) that the five most common cancers with H2B mutations are endometrial cancer (13.8%), bladder urothelial cancer (13.4%), cervical squamous cell carcinoma (10.8%), head and neck squamous cell carcinoma (10.3%) and esophageal squamous cell carcinoma (9.5%).