AFP and hepatocellular carcinoma: Spearman rank correlation analysis revealed that the level of serum Sphingosine (d18:1)-1-P was not correlated with AFP in cirrhosis (r = −0.04, P = 0.71), total HCC (r = 0.06, P = 0.60), AFP-positive HCC (r = −0.09, P = 0.56), or AFP-negative HCC (r = −0.13, P = 0.55), respectively.