The NETest was performed prior to the start of chemotherapy in 60 patients who were histologically re-classified as follows: 45 cases were classified as HG GEP-NET (12 cases as NET G3, 30 as neuroendocrine carcinoma-NEC, and 3 cases with ambiguous morphology); 1 case was re-classified as a small intestinal NET G2 with Ki-67 of 18%; 8 cases were classified as mixed non-neuroendocrine and neuroendocrine neoplasm (MiNEN), 3 cases as adenocarcinomas with neuroendocrine differentiation (ADNE) with intense synaptophysin staining, and an additional 3 cases re-classified as adenocarcinomas. Here, SYP is linked to neuroendocrine carcinoma.