Is Lymph Node Metastasis an Event Indicating an Advanced Gastrointestinal Stromal Tumor?

754 Background: The clinicopathological features and prognosis of gastrointestinal stromal tumors (GISTs) with lymph node metastasis remain controversial owing to their low incidence. A multicenter retrospective cohort study was conducted to compare the clinicopathological features and oncologic outcomes of GIST with and without lymph node metastases. Methods: The medical records of patients with GISTs in 16 large medical centers in China from January 2014 to December 2020 were reviewed. Patients were divided into three groups: no metastasis, lymph node metastasis without distant metastasis, and distant metastasis without lymph node metastasis. Propensity score matching (PSM) was performed to reduce confounding factors. Results: A total of 1109 cases of primary GIST were included in this study, comprising 607 males (54.7%) and 502 females (45.3%), with a mean age of 56.6±11.9 years. There were 1024 patients (92.3%) with no lymph node metastasis after surgery, and 85 patients (7.7%) had lymph node metastasis. Compared to that in GIST without lymph node metastasis, the proportion of non-gastric GIST was higher in GIST with lymph node metastasis (52.9% vs. 40.7%) with a larger tumor diameter (>10 cm: 36.5% vs. 18.1%) and more patients with distant metastasis (11.8% vs. 3.5%). Tumor location not in the stomach, the largest tumor diameter, and distant metastasis were independent risk factors for GIST with lymph node metastasis (all P < 0.05). After PSM, 96, 48, 24 patients comprised no metastasis, lymph node metastasis without distant metastasis, and distant metastasis without lymph node metastasis, respectively. The relapse-free survival (RFS) of the lymph node metastasis group was comparable to that of the distant metastasis group without lymph node metastasis ( P = 0.368) and significantly inferior to that of no metastases ( P = 0.042). Conclusions: The prognosis of patients with GIST with lymph node metastasis was comparable to that of patients with distant metastasis and significantly worse than that of patients without metastasis. Lymph node metastasis may be an advanced event in GIST.