BACKGROUND/AIMS: Assessment of malignant potential in gastrointestinal stromal tumor (GIST) is still problematic. The maximum tumor diameter and the mitotic index are generally used as an index of malignancy of GISTs. The Ki-67 labeling index has recently been used as an index of cell growth. The aim of this study was to investigate the prognostic value of Ki-67 in GIST. METHODS: We retrospectively reviewed the medical records of 32 patients with GIST who underwent surgical resection at Inje University Seoul Paik Hospital. We analyzed their Ki-67 expression, histologic finding, and prognosis. RESULTS: According to the tumor size and mitotic count, 4 patients were classified as very low risk, 9 patients as low risk, 14 patients as intermediate risk and 5 patients as high risk. The average Ki-67 index was 5.56+/-4.48%. The median follow-up duration was 35.72+/-29.04 months, and local/distant recurrences were observed in 6 (18.7%) patients. The overall cumulative disease free survival rates in patients with Ki-67 index < or =5% at 1 year, 2 years, and 5 years were 100%, 100%, and 86%, respectively. The overall cumulative disease free survival rates in patients with Ki-67 index >5% were at 1 year, 2 years, and 5 years were 82.1%, 70.3%, and 46.9%, respectively. There was significant relationship between elevated Ki-67 and disease free survival rate (p=0.007). CONCLUSIONS: Our study suggests that Ki-67 index >5% confers a higher risk of relapse in patients with GIST. Future work should focus on standardization of Ki-67 assessment and specification of its role in making treatment decisions.
Adult ; Aged ; Disease-Free Survival ; Female ; Gastrointestinal Neoplasms/*diagnosis/mortality/pathology ; Gastrointestinal Stromal Tumors/*diagnosis/mortality/pathology ; Humans ; Immunohistochemistry ; Kaplan-Meier Estimate ; Ki-67 Antigen/*metabolism ; Linear Models ; Male ; Middle Aged ; Neoplasm Recurrence, Local ; Prognosis ; Retrospective Studies

This study investigated the expression and clinicopathological significance of CD9 in gastrointestinal stromal tumor (GIST). Immunohistochemistry staining for CD9 was performed on tumor tissues from 74 GIST patients. The correlation with clinicopathological features, risk classification and prognosis was analyzed. CD9-positive staining comprised 59.5% (44/74) of the GIST patients. The CD9-positive expression rate of the sample was significantly associated with diameter (P = 0.028), mitotic counts (P = 0.035), risk classification (P = 0.018) and three-year recurrence-free survival (RFS) (P < 0.001). Cox proportional hazards regression (HR = 0.352; P = 0.015) showed that CD9 is an independent factor for post-operative RFS. The subgroup analysis showed that CD9 expression in gastric stromal tumor (GST) is significantly associated with diameter (P = 0.031), risk classification (P = 0.023) and three-year RFS (P = 0.001). The Cox proportional hazards regression (HR = 0.104; P = 0.006) also showed that CD9 is an independent factor for RFS of GST. However, CD9 expression does not have a statistically significant correlation with clinicopathological features, risk classification, and prognosis in non-GST. In conclusion, CD9 expression in GIST appears to be associated with the recurrence and/or metastasis of GIST patients, especially in GST, which may indicate the important role of CD9 in the malignant biological behavior and prognosis of GST.
Adult ; Aged ; Aged, 80 and over ; Antigens, CD9/*genetics/*metabolism ; Disease-Free Survival ; Female ; Gastrointestinal Neoplasms/metabolism/mortality/*pathology ; Gastrointestinal Stromal Tumors/metabolism/mortality/*pathology ; *Gene Expression Regulation, Neoplastic ; Humans ; Immunohistochemistry ; Kaplan-Meier Estimate ; Male ; Middle Aged ; Prognosis ; Proportional Hazards Models ; Risk Factors