In PAAD and STAD cases, a significant positive correlation with all four Treg markers was detected, but the expression levels of forkhead box protein P3 (FOXP3) and C-C motif chemokine receptor 8 (CCR8) were not significantly correlated with COL4A1 expression levels in LGG, SKCM, and LGG (Table 1 and Figure 5). Here, COL4A1 is linked to pancreatic adenocarcinoma.