Reevaluation of prognostic factors in gastric leiomyosarcoma.

OBJECTIVES: The aim of our study was to reevaluate the prognostic factors in gastric leiomyosarcomas, particularly those under 6 cm, which, because of improved diagnostic techniques, make up a large proportion of this series, in contrast to previously published works.

METHODS: The clinicopathological features in 83 patients with gastric leiomyosarcoma were reviewed. Cox's proportional hazards regression analysis was used to determine the prognostic factors.

RESULTS: Sixty of 84 leiomyosarcomas (71.4%) were less than 6 cm in diameter. In univariate analysis, the following factors were considered to be unfavorable, with statistical significances: 1) presence of distant metastasis and/or direct invasion of adjacent structures at diagnosis (hazard ratio 36.60), 2) > or = 4 mitoses per 20 high-power fields (25.39), 3) severe nuclear atypia (16.74); 4) presence of ulceration of overlying gastric mucosa (12.57), and 5) diameter > or = 6 cm (5.57). Among these factors, mucosal ulceration has been identified as a new factor associated with poor prognosis. Histologically, the tumors with ulceration showed more severe nuclear atypia (p < 0.05), necrosis (p < 0.01), and a higher incidence of mitosis (p < 0.01), compared with tumors without ulceration. In multivariate analysis, factors 1, 2, and 3 were statistically significant, although neither size nor ulceration was significant.

CONCLUSIONS: The presence of distant metastasis and/or direct invasion, high mitotic rate, and severe nuclear atypia were confirmed to be unfavorable prognostic indicators. Mucosal ulceration, indicating high proliferative activity of the tumor, even if small, suggests a poor prognosis, although it was not significant in multivariate analysis.