Table 1.
Clinicopathological characteristics and prognosis of neuroendocrine neoplasias of the stomach [9, 12, 16, 18, 19]
| Gastric NET G1 (carcinoids) and NET G2 |
Poorly differentiated NE gastric cancer (type 4): gastric NEC G3 | |||
|---|---|---|---|---|
| type 1 | type 2 | type 3 | ||
| Relative frequency, % | 70–80 | 5–6 | 14–25 | 6–8 |
| Features | mostly small (≤1 cm) and multiple | mostly small (≤1 cm) and multiple | often >2 cm, solitary | mostly >2 cm, solitary |
| Associated conditions | CAG | MEN1/ZES | no | no |
| Histology | well-differentiated G1/G2a | well-differentiated G1/G2a | well/moderately differentiated G1/G2b | G3 |
| Serum gastrin | (very) high | (very) high | normal | (mostly) normal |
| Gastric pH | anacidic | hyperacidic | normal | (mostly) normal |
| Metastases, % | <10 | 10–30 | 30–80 | 80–100 |
| Tumor-related deaths, % | no | >10 | 25–30 | >50 |
a
Most type 1 and type 2 gastric NET G2 show a Ki-67 expression of ≤5%.
b
Some type 3 gastric NET, though well-differentiated, show a Ki-67 index of >20% (NET G3).
CAG = Chronic atrophic gastritis; MEN1 = multiple endocrine neoplasia type 1; ZES = Zollinger-Ellison syndrome; MEN1/ZES = ZES associated with MEN1; G1 and G2 = well-differentiated; G3 = poorly differentiated (Ki-67 index of 0–2%: G1; Ki-67 index of 3–20%: G2; Ki-67 index of >20%: G3); NE = neuroendocrine; NET = neuroendocrine tumor; NEC = neuroendocrine carcinoma.