MLH1 and ovarian carcinoma: Promoter region hypermethylation of MLH1 is also found in other sporadic tumors, including adult T-cell leukemia/lymphoma (6%) [66], gastric cancer (21.6%) [67], head and neck squamous cell carcinomas (28.6%) [68], non-small cell lung cancer (55.8%) [69], oral squamous cell carcinoma (76%) [70], esophageal squamous cell carcinoma (23%) [71], pancreatic cancer (23%) [72], ovarian cancer (37.5%) [73], and breast cancer (31.3%) [74].