Background: Ki67 index is one of the most important immunocytochemical markers of proliferation in tumors, but the criterion of Ki67 index in GISTs was not well-defined yet. Our study aims to fully evaluate the prognostic value of Ki67 index in GIST patients and efficiency of imatinib adjuvant therapy.
Methods: Clinicopathological data were confirmed by pathological diagnosis and clinical recorders. Recurrence-free survivals (RFS) were evaluated in 418 GIST patients (370 cases only taken the surgery and 48 high-risks taken imatinib adjuvant therapy after R0 resection).
Results: Two cutoff levels of Ki67 index (>5 and >8%) were established in our study through statistical analysis. Ki67 index (≤5, 6-8 and >8%) is an independent prognostic factor for RFS of GIST patients. Ki67 index>8% can precisely sub-divide high-risk GISTs effectively with different outcomes, and high-risk patients with Ki67 index>8% showed a poorer prognosis even with imatinib adjuvant therapy.
Conclusion: Ki67 index is an effective complementation of modified NIH criteria in predicting the prognosis of GISTs, and Ki67 index>8% may act as an unfavorable factor for imatinib adjuvant therapy.
Keywords: Gastrointestinal stromal tumor; Ki67; prognosis; targeted therapy.