Elevated (≥10%) MIB-1 proliferative index correlates with poor outcome in gastric stromal tumor patients:: A study of 35 cases

Mitotic activity and tumor size are currently regarded as the most powerful prognostic indicators for patients with gastrointestinal stromal tumor (GIST). This retrospective study evaluated the prognostic accuracy of MIB-1 proliferative index (PI) in combination with these two indicators in 35 GIST patients. Within a high-risk group, determined initially by tumor size and mitotic count, overall survival was significantly shorter for patients whose tumors had PI greater than or equal to 10% MIB-1 positive cells. When tumor location (gastric versus small intestine) was taken into account, a combination of tumor size, mitotic count, and PI greater than or equal to 10% identified a subgroup of patients with significantly shorter survival for gastric (but not small intestinal) GIST. Based on our results, MIB-1 immunostaining, when used in combination with tumor size and mitotic count, appears to be a powerful tool for identifying patients, especially those with gastric tumors, at high risk of recurrence and early tumor-related death.