Long-term course of gastric submucosal tumors: growth speed and size-increasing factors

Gastric submucosal tumors (SMTs) are treated or monitored according to GI stromal tumor guidelines, but the adequacy of the guidelines has not been thoroughly examined. We investigated the long-term course of gastric SMTs to determine the validity of guideline-based follow-up methods and the factors contributing to their size increase.

This study included gastric SMTs diagnosed as GI mesenchymal tumors (GIMTs) by using EUS and followed up with EUS. The percentage and speed of GIMT enlargement and factors associated with the enlargement were investigated by using the Cox proportional hazards model.

From January 1994 to May 2022, a total of 925 gastric SMTs were evaluated with EGD, and 231 SMTs were diagnosed as GIMTs. Of the 231 GIMTs, 145 were examined by EUS more than twice and were followed up for >6 months. The mean ± standard deviation follow-up period was 5.20 ± 4.04 years (range, 0.5-17.3 years), with 39 (26.9%) of 145 GIMTs increasing in size with a mean doubling time of 3.60 ± 3.37 years. A multivariate analysis of factors influencing tumor growth revealed that irregular extraluminal borders were an increasing factor (hazard ratio, 3.65; 95% confidence interval, 1.26-10.52), initial tumor size ≤9.5 mm (hazard ratio, .23; 95% confidence interval, 0.07-0.77) was a nonincreasing factor, and GIMTs with calcification (n = 13) did not increase in size.

Tumor growth in gastric GIMTs <9.5 mm in diameter and/or with calcification is rare. Follow-up intervals for these lesions could be extended.