The expression of APOBEC3B in NETs was significantly higher than that in NECs, NET G1 and NET G2 were higher than NET G3, and the difference was statistically significant.
The 5-year OS of patients with NET G1 was significantly higher than that of patients with NET G2 (P=0.015) and NEC G3 (P<0.001); the comparison of OS for patients with NET G2 and NEC G3 was also statistically significant (P=0.005).
Similar risk of progression was observed between NET G1 and NET G2 tumors (median PFS 11 months and 8 months, respectively), and between patients who had received ≥ 3 vs ≤ 2 therapeutic approaches before sunitinib (median PFS 9 months and 10 months, respectively).
Applying the WHO 2010 grading system to whole NENs originating in the gastroenteropancreatic system, R-NENs are classified as Well-Differentiated Neuroendocrine Tumors (WD-NET), which contain NET G1 and NET G2, and Poorly-Differentiated Carcinomas (PD-NEC) enclosing only G3 neoplasms for which the term carcinoma is applied.
We identified 414 patients with GI-NENs, 250 cases were diagnosed as neuroendocrine tumor G1 (NET G1), 25 as neuroendocrine tumor G2 (NET G2), 53 as neuroendocrine tumor G3 (NET G3), 55 as neuroendocrine carcinoma G3 (NEC G3), and 31 as mixed adenoneuroendocrine carcinoma (MANEC); the overall survival (OS) rate at three years were 94.9%, 91.7%, 74.3%, 62.7% and 38.1%, respectively.
At histological examination, 81 patients had a gastric neuroendocrine neoplasia (42 patients had a NET G1 and 33 a NET G2).The median Ki67 index was 2.0 %.