Introduction
Japanese gastrointestinal stromal tumor (GIST) guidelines recommend that gastric submucosal tumors (SMT) < 2 cm should be followed up once or twice a year if asymptomatic and without malignant findings (ulceration, irregular border, and/or tumor growth), and SMT with malignant findings or a pathological diagnosis of GIST are relative indications for surgery1. However, this management policy for SMT < 2 cm has not been fully evaluated.
Aims & Methods
This study aimed to clarify the long-term outcomes of patients with endoscopically diagnosed gastric SMT < 2 cm managed according to the guidelines. Patients with endoscopically diagnosed gastric gastrointestinal mesenchymal tumors (eGIMT) < 2 cm, including GIST, leiomyomas, and schwannomas, at our institution between September 2002 and December 2020 were included in this study. eGIMT was defined as an SMT with the same color as the surrounding mucosa, negative cushion sign, and mobility by biopsy forceps and/or a hypoechoic mass arising from the fourth layer of the gastric wall on endoscopic ultrasonography (EUS). The success rates of histological diagnosis by biopsy and EUS-guided fine needle aspiration biopsy (EUS–FNAB), rate of eGIMT with tumor growth during the endoscopic follow-up period, predictive factors of tumor growth, disease-specific survival (DSS), and overall survival (OS) rate were retrospectively evaluated. Tumor growth was defined as an increase in tumor size of approximately ≥ 5 mm compared to the initial tumor size, as measured by endoscopy. Factors associated with tumor growth like age, sex, number of lesions, stomach location, atrophic gastritis, and initial tumor size were considered for predictive analysis.
Results
A total of 1,519 patients with 1,632 eGIMTs were enrolled in this study. The median age at the initial diagnosis of eGIMT was 66 years (range, 28–90 years), and 60% of the patients were males. The percentage of patients who underwent EUS was 16%. The tumor locations were upper in 71%, middle in 20%, and lower in 9%, with the median initial tumor size being 5 mm and 24% were ≥ 1 cm. The success rates of histological diagnosis using biopsy and EUS-FNAB for eGIMT were 12% and 87%, respectively. Among the 927 patients with 995 eGIMTs examined at least twice by endoscopy and followed up endoscopically for at least 1 year, tumor growth was observed in 3.8% (median endoscopic follow-up period, 5.3 years). Of these, 33 patients underwent surgery or endoscopic resection, and the final pathological diagnoses of eGIMT were 4 high-risk GISTs, 1 intermediate-risk GISTs, 15 low-risk GISTs, 9 very low-risk GISTs, and 3 schwannomas. In univariate analysis, the only predictive factor of tumor growth was initial tumor size (< 1 cm: 1% vs. ≥ 1 cm: 14%, p < 0.0001). The 5–year DSS and 5–year OS rates of all patients with an eGIMT < 2 cm were 100% and 86%, respectively (median follow-up period, 5.2 years).
Conclusion
The long-term outcomes of patients with an eGIMT < 2 cm managed according to the current guidelines were favorable. Tumor growth in patients with an eGIMT < 1 cm is rare and may allow for extended follow-up intervals.
References
1. Nishida T, Hirota S, Yanagisawa A, et al. Clinical practice guidelines for gastrointestinal stromal tumor (GIST) in Japan: English version. Int J Clin Oncol 2008;13:416-30.
