Circulating Tumor DNA Guided Adjuvant Chemotherapy for Colon Cancer

The IDEA study classified stage III colon cancer into low-risk (T1-3/N1) and high-risk patients (T4 or N2) according to TNM stage. The results showed that for some low-risk patients, chemotherapy could be reduced without survival loss.

In recent years, circulating tumor DNA had achieved encouraging results in monitoring recurrence and metastasis after surgery, and has potential clinical application value. Postoperative ctDNA is also considered as a marker of increased risk of recurrence for stage I-III colon cancer and can provide predictive information for decision making on adjuvant treatment.

The results of GERCOR-PRODIGE, concomitant study of IDEA-FRANCE, showed that in the high-risk group, the patients with ctDNA positive and receiving adjuvant chemotherapy for 6 months had similar prognosis as the patients with ctDNA negative and receiving chemotherapy for 3 months; in the low-risk group, the patients with ctDNA positive but receiving chemotherapy for 3 months had worst prognosis, and the prognosis of patients with ctDNA negative chemotherapy for 3 months and 6 months and ctDNA positive chemotherapy for 6 months were similar. This indicates that risk stratification can be further performed according to the results of ctDNA after clinical pathological staging. Pathological staging is still an important decision-making factor for chemotherapy. It is not reliable to the chemotherapy decision making just based on ctDNA and abandoning clinical staging.

Therefore, a prospective, multicenter, open-label, randomized controlled clinical trial was designed aimed to investigate circulating tumor DNA guided adjuvant chemotherapy for colon cancer. In this study, all the patients are divided into high-risk group and low-risk group according to the postoperative pathology. Patients in each group were randomized to different treatment schedule according to the results of ctDNA.