THBS1 and gastric cancer: The results showed that 98.2% (54/55) GC patients with THBS1 methylation exhibited the same alteration in their PPLF DNAs, and 87.3% (48/54) GC patients with THBS1 methylation demonstrated the identical alteration in corresponding serum DNAs, while no THBS1 methylation was detected in corresponding PPLF and serum specimens in 37 GC patients with negative THBS1 methylation in tumor tissues (Figure 1).