Liquid Biopsy After Resection of Stage II Colon Cancer Reduced the Need for Adjuvant Chemotherapy

Patients with stage III (node-positive) colorectal cancer (CRC) benefit from adjuvant chemotherapy. Patients with stage II (invading muscularis propia or deeper and node-negative) CRC typically receive adjuvant chemotherapy if they have high-risk clinical pathologic features, particularly T4 disease.

In a randomized trial from Australia, 455 patients with stage II CRC were assigned to standard management that included decision-making for adjuvant chemotherapy based on clinical pathologic features versus management guided by circulating tumor DNA (ctDNA), in which blood samples taken at 4 weeks and 7 weeks were used to identify minimal residual disease and the need for adjuvant chemotherapy. 

Only 15% of patients in the ctDNA group received adjuvant chemotherapy versus 28% in the standard-management group. At 2 years, the ctDNA-guided management group had 93.5% recurrence-free survival compared with 92.4% in the standard-management group. Median time to chemotherapy initiation was longer in the ctDNA-guided group than in the standard-management group (83 vs 53 days). This was driven by time to wait for a ctDNA result, which required 2 weeks for turnaround, and ctDNA testing of specimens obtained at 4 and 7 weeks was not performed until the 7-week sample was drawn.