ObjectiveTo detect level of circulating tumor cells (CTCs) in peripheral venous blood of fasting patients with gastric cancer (GC) and to analyze relationships between CTCs and clinicopathologic features and prognosis of patients with GC.MethodsOne hundred patients with GC were selected (GC group), who underwent the surgery and confirmed by the histopathology in the 940 Hospital of Joint Service of PLA, from August 2015 to December 2016. Thirty-eight patients with gastric benign lesions who were treated in this hospital at the same time were selected as the control group. The 7 mL peripheral venous blood of the elbow in the morning was taken from the fasting patients and the CTCs were detected by the immunomagnetic microparticle negative enrichment combined with immunofluorescence in situ hybridization within 24 h. The positive rate of CTCs was calculated and its relationships with the clinicopathologic features (tumor location, tumor invasion depth, degree of differentiation, TNM stage, lymph node metastasis, and vascular tumor thrombus) and the progression-free survival of the patients with GC were analyzed.ResultsThe positive rate of peripheral venous blood CTCs in the GC group was 89.0% (89/100), which was higher than that in the control group (10.5%, 4/38), and the difference was statistically significant (P<0.001). The levels of CTCs in the patients with GC were significantly correlated with the tumor invasion depth (P=0.017), lymph node metastasis (P=0.038), and TNM stage (P=0.016), which were not associated with the age, gender, tumor location, degree of differentiation, and vascular tumor thrombus (P>0.050). The predictive value of CTCs for the diagnosis of GC was significantly superior to that of the tumor markers CEA, CA19-9, or CA125. The progression-free survival of patients with low CTCs expression was significantly longer than that in the patients with high CTCs expression (χ2=5.172, P=0.023).ConclusionsDetecting CTCs of patients with GC by immunomagnetic particle negative enrichment combined with immunofluorescence in situ hybridization has a high sensitivity. And it can improve early diagnosis of patients with GC. Preoperative CTCs detection has a certain value in guiding staging of GC and predicting prognosis of patients with GC.