When analyzing the expression of CDX2 by immunohistochemistry in our patient cohort, we found that SOX2 positive tumors were highly associated with a decreased expression of CDX2; 73.9 % of the SOX2 positive tumors had less than 50 % CDX2 positive tumor cells, and of these 32.6 % had less than 5 % positive cells. This evidence concerns the gene SOX2 and neoplasm.