Meanwhile, when the six patients with tumors harboring >1% CD26+ cell population were examined (patients 6–11), four of them were already diagnosed with metastatic disease (stage IV) at the time of surgery as mentioned above; the other two patients who had a particularly high proportion of CD26+ tumor cells had an initial pathological stage of IIA according to the TNM classification. This evidence concerns the gene DPP4 and metastatic neoplasm.