Even though OCTN2 expression level does not seem to affect the proliferation of primary patient-derived cancer cells, it cannot be excluded esophageal cancers with high expression of OCTN2 and high accumulation of L-carnitine being less aggressive than those expressing low levels of the transporter, which would make OCTN2 also a candidate prognostic marker. This evidence concerns the gene SLC22A5 and esophageal cancer.