With regard to C6 sulfation, no HS6ST2 transcripts could be detected, and the levels of HS3ST3 were very low and displayed considerable variation between patients; however, HS6ST1 was the major isoform present in all cases, and furthermore displayed a statistically significant decrease in non-metastatic tumors (p = 0.007), values being on average 5 times lower in 100 % of the cases analyzed (Fig. 6). This evidence concerns the gene HS6ST1 and metastatic neoplasm.