Postoperative circulating tumor DNA detection predicts recurrence and guides adjuvant chemotherapy duration in high-risk stage III colorectal cancer

Figure 1 Circulating tumor DNA mutation spectrum in high-risk stage III colorectal cancer patients (all 50 enrolled patients). The bar chart illustrates the mutation frequencies of key oncogenes and tumor suppressor genes detected in circulating tumor DNA among 50 enrolled high-risk stage III colorectal cancer patients. KRAS exhibited the highest mutation frequency (42.3%), followed by TP53 (23.8%), APC (19.0%), and NRAS (14.3%). PIK3CA and BRAF showed intermediate frequencies (9.5% and 9.3%, respectively), while ERBB2, RET, and NTRK were the least frequently mutated genes (4.0% each). These findings indicate that KRAS and TP53 mutations are the predominant somatic alterations identified in the circulating tumor DNA of this patient cohort.

Figure 2 Kaplan-Meier analysis of recurrence-free survival according to postoperative circulating tumor DNA status and adjuvant chemotherapy duration. A: Kaplan-Meier curves for recurrence-free survival (RFS) stratified by postoperative circulating tumor DNA (ctDNA) status. The curves represent ctDNA-positive and ctDNA-negative patients (Log-rank P = 0.026); B: Kaplan-Meier curves for RFS in ctDNA-positive patients stratified by chemotherapy duration. The curves represent the 3-month and 6-month capecitabine plus oxaliplatin (CapOX) chemotherapy subgroups (Log-rank P = 0.689); C: Kaplan-Meier curves for RFS in ctDNA-negative patients stratified by chemotherapy duration. The legend represents the 3-month and 6-month CapOX chemotherapy subgroups (Log-rank P = 0.512); D: Kaplan-Meier curves for RFS comparing ctDNA-positive patients receiving 3 months of CapOX chemotherapy and ctDNA-negative patients receiving 6 months of CapOX chemotherapy (Log-rank P = 0.038). ctDNA: Circulating tumor DNA; CapoX: Capecitabine plus oxaliplatin.

Figure 3 Time to recurrence analysis by circulating tumor DNA status and chemotherapy duration. Box plots showing the distribution of time to recurrence. A: Comparison between circulating tumor DNA (ctDNA)-positive (n = 10) and ctDNA-negative (n = 5) patients. ctDNA-positive patients had significantly shorter median time to recurrence (11.0 months vs 18.0 months, P = 0.041, Mann-Whitney U test); B: Comparison between 3-month (n = 6) and 6-month (n = 4) chemotherapy durations in ctDNA-positive patients. No significant difference was observed (9.5 months vs 14.0 months, P = 0.167). Box plots display the median (horizontal line), mean (diamond), interquartile range (box), and range (whiskers). ctDNA: Circulating tumor DNA; NS: Not significant.