Sensitivity and specificity of folate receptor α-positive circulating tumour cells in gastric cancer

Abstract Purpose We aimed to investigate whether folate receptor α (FRα)-positive circulating tumour cells (CTCs) could be used as a noninvasive liquid biopsy approach in gastric cancer (GC). Methods Tissue microarray and bioinformatic analyses were used to evaluate FRα expression in GC. Patients with FRα-positive CTC examinations at our institute between July 2021 and May 2022 were retrospectively evaluated. Receiver operating characteristic curves were used to evaluate the diagnostic performance of FRα-positive CTCs in GC. Results FRα was highly expressed and associated with poor prognosis in GC based on public database. Data for 163 patients (20 with benign disease and 143 with GC) were retrospectively collected. FRα-positive CTC levels were significantly higher in the GC group than in the benign disease group (12.15 ± 1.47 FU/3 ml vs. 10.47 ± 1.63 FU/3 ml, P < 0.01). FRα-positive CTC levels were also elevated in GC patients with vessel/neuron invasion or extra-nodal tumour deposits (12.31 ± 1.47 FU/3 ml vs. 11.77 ± 1.38 FU/3 ml, P = 0.037). Areas under the curve of FRα-positive CTC levels for GC and early GC were 0.774 (P < 0.001) and 0.736 (P = 0.005). With a cut-off value of 10.95 FU/3 ml, the Youden indexes for GC and early GC were 0.502 (sensitivity = 85.2% and specificity = 65.0%) and 0.450 (sensitivity = 80.0% and specificity = 65.0%), respectively. Conclusion FRα-positive CTC detection by noninvasive liquid biopsy is a useful and effective approach for screening of patients with GC. Key messages What is already known on this topic Early detection is important in the treatment of gastric cancer. However, noninvasive diagnostic techniques with adequate sensitivity are lacking. What this study adds The diagnostic performance of folate receptor-positive circulating tumour cells was better than that of carcinoembryonic antigen. With the optimal cut-off values, the sensitivities of folate receptor-positive circulating tumour cells in the diagnosis of gastric cancer and early gastric cancer were 85.2% and 80.0%, respectively. How this study might affect research, practice, or policy Folate receptor-positive circulating tumour cell examination is a promising noninvasive approach for the screening of patients with gastric cancer.