p53 and MIB-1 expression in gastrointestinal stromal tumor (GIST) of the stomach

Background/Aims: Routine clinical approaches for evaluating the risk of recurrence in patients with gastrointestinal stromal tumor (GIST) of the stomach have been limited. Some biomolecular markers may yield more useful information in identifying patients having a higher risk of recurrence. In the current retrospective study, we selected MIB-1 and p53 expression as markers to detect at-risk patients. Methodology: We enrolled 31 gastric GIST patients who underwent gastrectomy at Kagoshima University Hospital. Patients were classified into two groups based on mitosis and tumor diameter. p53 and MIB-1 expression in the primary tumor were detected immunohistochemically. Results: The patients were classified as having a malignant GIST (20 cases), a benign GIST (11 cases). MIB-1 labeling index (LI) varied from 1 to 32% (average 7.8%). The MIB-1 LI for malignant GISTs was 6.3 +/- 6.4%, which was significantly higher than the 3.2 +/- 2.5% observed for benign GISTs (p < 0.01). The 3 patients positive for p53 died as a result of GIST recurrence. Conclusions: In addition to routine pathological evaluation, expression of p53 and MIB-1 may provide more accurate information regarding the risk of GIST recurrence. Especially, p53 expression of the tumor may indicate patients having a high risk of recurrence.