Circulating tumor DNA analysis for prediction of prognosis and molecular insights in patients with resectable gastric cancer: results from a prospective study

This study aimed to evaluate the prognostic value of plasma circulating tumor DNA (ctDNA) level in patients with resectable gastric cancer (GC). A total of 59 patients were prospectively enrolled, with their ctDNA detected and paired tumor tissue collected at various peri-operative time points. Patients with higher 1-month post-operative ctDNA levels demonstrated shorter overall survival status (hazard ratio [HR] = 5.30, p = 0.0022) and a higher risk of recurrence (HR = 3.85, p = 0.011). The model combining ctDNA with conventional serum tumor markers for GC, including carcinoembryonic antigen, carbohydrate antigen 19-9, and CA72-4, shows high predictive effectiveness for GC prognosis with an area under the curve of 0.940 (p = 0.002), which is higher than net ctDNA and other models without ctDNA. Patients with lower ctDNA levels were more likely to have positive stromal programmed cell death ligand 1 expression (p = 0.046). Additionally, DCAF4L2 mutation was identified as the crucial gene mutation in ctDNA suggesting poor prognosis of patients with GC. Overall, this study highlights that post-operative ctDNA can serve as an effective biomarker for prognostic prediction and recurrence surveillance in resectable GC.