The choice to test both the G and the Ki67 value in parallel derives from the fact that the cut-off to differentiate G1 from G2 p-NETs from a prognostic point of view is controversial [3,35], particularly for G2 sub-category which includes a too-wide range of tumors, ranging from benign tumors, which benefit from more conservative management, to malignant tumors which have a much more aggressive behavior. This evidence concerns the gene MKI67 and cancer.