As mentioned in the supplementary method, a systematic search of electronic databases for the cancer stem cell markers of neuroendocrine tumors was performed, a total of fifteen markers were found to have been reported previously (Supplementary Table S5), in which we found four markers were reported in more than one study, including ALDH1, CD133, CD44, and SOX9. This evidence concerns the gene SOX9 and neuroendocrine neoplasm.