Small intestinal neuroendocrine tumours (Si-NET) are grouped according to their proliferation index (Ki-67) into grade 1 (G1, Ki-67 <3%), grade 2 (G2, Ki-67 3–20%) and grade 3 (G3, Ki-67 >20%) (Klimstra et al. 2019). This evidence concerns the gene MKI67 and small intestine neuroendocrine neoplasm.