PURPOSE: The present study was undertaken to investigate the possibility of determining a prognosis for gastrointestinal tract leiomyosarcoma with the use of DNA analysis and MIB-1 staining.SUBJECTS AND METHODS: Malignant tumors originating in smooth muscle of the gastrointestinal tract, surgically excised from 23 lesions in 17 patients (stomach; 8 cases, 12 lesions; small intestine: 6 cases, 8 lesions; colon: 3 cases, 3 lesions) and embedded in paraffin, were examined. DNA was analyzed using flow cytometry to produce a DNA histogram, and aneuploidy and diploidy were found. MIB-1 staining was done in conformity with the ABC method.RESULTS: 1. An investigation of prognoses using the Kaplan-Meier method revealed a tendency for more favorable prognoses in patients determined to be aneuploid through DNA analysis. However, this was not significantly better than those exhibiting diploidy. 2. All patients who died had a MIB-1 staining positivity rate of over 10%, while all patients who had no recurrence within one year or survived had a MIB-1 staining positivity of less than 10%. 3. No consistent trends were observed between MIB-1 positivity rate and DNA analysis, MIB-1 positivity rate and size of tumor, or DNA analysis and size of tumor. 4. The MIB-1 positivity rate of patients with remote metastases was significantly greater than that of patients with no remote metastases.CONCLUSION: From the fact that patients with MIB-1 positivity rates of greater than 10% had a poor prognosis, while those with rates of less than 10% had a favorable prognosis, we conclude that a MIB-1 positivity rate of 10% is an important value in determining the prognosis of patients with gastrointestinal tract leiomyosarcomas.
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