Proliferating-cell nuclear antigen immunocytochemistry in the evaluation of gastrointestinal smooth-muscle tumors.

Current methods do not provide a way always to distinguish benign from malignant gastrointestinal smooth-muscle tumors. We compared immunocytochemical assessment of proliferating-cell nuclear antigen expression with flow cytometry and mitotic figure-counting as a prognostic marker in 85 gastrointestinal smooth-muscle tumors. Although proliferating-cell nuclear antigen expression was associated with poor prognosis in univariate statistical analysis, it was not significant in multivariate proportional hazards models that included either the mitotic index or aneuploidy of the flow-cytometric G2M peak. We conclude that proliferating cell nuclear antigen assessment is not warranted in the routine evaluation of gastrointestinal smooth-muscle tumors.