Reevaluation of prognostic factors in gastric leiomyosarcoma

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.

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

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.

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.