CEACAM5 and adenocarcinoma: High levels of CEA have been reported in various NECs, including breast (54.4 ng/mL) [15], gallbladder (723 ng/mL) [16], prostate (11.15 ng/mL) [17], and anal canal poorly differentiated adenocarcinoma with neuroendocrine features (809.4 ng/mL)[18], and glucagonoma in the pancreas (660 ng/mL) [19].