Furthermore, previous reports assessing the prognostic significance of the expression of S1P-producing enzyme (Sphk1) or S1P receptor (S1P1) in tumor tissues revealed a significant correlation with shorter OS in NSCLC patients treated with adjuvant platinum-based chemotherapy [53], and in hepatocellular carcinoma [52] or bladder cancer patients [54], respectively. This evidence concerns the gene SPHK1 and hepatocellular carcinoma.