Nevertheless, Guo et al. [200] in a large study investigating a CTC-derived PCR score (quantifying the expression of cancer-related genes in blood), demonstrated a sensitivity of 72.5%, a specificity of 95%, and an AUC of 0.88 (compared with 57%, 90%, and 0.77 of AFP at a cut-off of 20 ng/mL). This evidence concerns the gene AFP and cancer.