The proliferation index, Ki-67, which is of importance for the malignant potential in neuroendocrine tumors, has been studied thoroughly in a study by Tang et al. They categorized GCC patients in 3 groups according to histology; group A, B, and C, respectively, and showed that the average Ki-67 index increases within the groups, and that the survival rate is significantly reduced with increasing Ki67 index [12]. Here, MKI67 is linked to neuroendocrine neoplasm.