THBS1 and neoplasm: The correlation analysis revealed that THBS1 methylation in PPLF was positively correlated with THBS1 methylation in tumor tissue (γ = 0.9673, p < 0.0001) and THBS1 methylation in serum was also positively correlated with methylation in the tumor tissue (γ = 0.9521, p < 0.0001) (Figure 2).