MKI67 and gastrointestinal stromal tumor: In line with these observations, most GISTs in our series presented at an advanced local stage (predominantly pT3–pT4), and their Ki-67 index, although lower than in non-GIST tumors, increased with tumor size, contributing to the overall positive correlation between size and proliferative activity (ρ = 0.42, p = 0.018).