TABLE 2.
Classification of Gastroenteropancreatic NETs (21)
| Differentiation | Grade | Ki-67 index | Proliferative rate | SSTR PET positivity |
| Well differentiated | Low grade (G1) | <3% | <2 mitoses/10 hpf | +++ |
| Intermediate grade (G2) | 3%–20% | 2–20 mitoses/10 hpf | ++ | |
| Poorly differentiated | High grade (G3) | >20% | >20 mitoses/20 hpf | Variable* |
hpf = high-power field.
*
In high-grade NETs, SSTR positivity is variable, and frequently 18F-FDG PET performs better as an imaging study in patients with these NETs. SSTR PET results may be positive for well-differentiated G3 tumors, and imaging may be helpful in finding patients who are candidates for PRRT.