Strong correlations were observed between tumor markers, with CA19-9 showing a positive correlation with CEA in both rPDAC (r = 0.550, p < 0.001) and mPDAC (r = 0.623, p = 0.002), while SYPL-1 demonstrated a negative correlation with CEA (r = −0.530, p = 0.009) in mPDAC. This evidence concerns the gene CEACAM5 and neoplasm.