Correlation between tumor volume doubling time and histologic findings in gastric smooth muscle tumors: clinical implications of tumor volume doubling time.

To assess the clinical implications of the tumor volume doubling time of gastric smooth muscle tumors based on a comparison with the histologic findings, seven tumors (four leiomyomas and three leiomyosarcomas) were followed up by consecutive upper gastrointestinal studies between March 1985 and December 1993. The patients were four men and three women with an average age of 58 years (range: 50-71 years). The observation period ranged from 6 to 51 months, with an average of 35 months. All tumors were surgically resected and the histologic diagnosis was confirmed. The following microscopic features were evaluated: 1) mitotic rate, 2) nuclear atypia, and 3) cellularity. Each tumor was also evaluated for the presence or absence of necrosis, hemorrhage, and degeneration. The doubling time ranged from 5 to 27 months with a mean of 16 months. There was a strong negative correlation between the mitotic rate and the doubling time (r = -0.935, P = 0.0019). The doubling time was also significantly related to nuclear atypia, but the number of tumors studied was so small that its reliability was questionable. The doubling time was not related to any other histologic findings. This study shows that the doubling time is useful for estimating the malignant potential of gastric smooth muscle tumors, and that tumors with a doubling time of 16 months or less should be considered as malignant.