PTGS2 and hepatocellular carcinoma: Based on our previous work [24,25], we selected several HCC-specific methylation regions, including Ras association domain family protein 1 isoform A (RASSF1A), MicroRNA 203 (miR-203), cyclooxygenase 2 (COX2), adenomatous polyposis coli (APC), aristaless-like homeobox 3 (ALX3), cg12582777, T-Box transcription factor 4 (TBX4), testis-specific Y-encoded protein-like protein 5 (TSPYL5), cg12714719, and cg08643930, to test their methylation levels before and after LRT.