[Flow cytometric quantitation of p53 protein expression in gastrointestinal smooth muscle tumors: clinicopathological correlation and prognostic significance].

Quantitative analysis of p53 protein expression was performed on paraffin-embedded tissues from 55 smooth muscle tumors of the gastrointestinal tract by using immunofluorescence and flow cytometry. No positive expression was found in normal smooth muscle tissues of the gastrointestinal tract. Overexpression of p53 gene was found in a significantly higher proportion in leiomyosarcomas (90%) and potential malignant smooth muscle tumors (75%) compared to leiomyomas (14%) (P < 0.005). The quantitation of p53 expression was found to be progressively enhanced in the sequence from leiomyoma through potential malignant smooth muscle tumor to leiomyosarcoma (P < 0.005). It was also overexpressed when mitotic counts were more than 1/10HPF or the mild cytologic atypia was found (P < 0.005). Five year survival rate was significantly higher in the patients with p53 lower expression compared to the patients with over-expression (P < 0.005). These results suggested that p53 overexpression might be associated with the transformation of leiomyoma into leiomyosarcoma, and could be used as an objective parameter in distinguishing malignants from benigns and predicting prognosis of the patients with smooth muscle tumors of the gastrointestinal tract.