If we assume that EC or L cells are progenitors of the neuroendocrine tumor cells, the hypothesis that the number of CgA producing EC cells decreases along the colon could explain why only a small proportion of patients in our collection of colorectal NEN exhibit significantly elevated CgA plasma levels, while the majority of our patients with colorectal NEN does not. This evidence concerns the gene CGA and neuroendocrine neoplasm.