We believe that our study is the first study reporting data on circulating levels of substance P previously to LT for HCC, an association between elevated levels of serum substance P before LT and mortality during the first year after LT controlling for liver donor age, and that serum levels of substance P before LT could be used for the prognosis estimation of one-year survival after LT. This evidence concerns the gene TAC1 and hepatocellular carcinoma.