Circulating tumor DNA analysis detects minimal residual disease and predicts recurrence in patients with stage II colon cancer
Detection of circulating tumor DNA in patients with resected stage II colon cancer provides evidence of residual disease. Footprints of persistent cancer Stage II colon cancer, which has spread through the wall of the colon but has not metastasized to the lymph nodes, can present a therapeutic dilemma. On one hand, these tumors can usually be completely removed by surgery, and the majority does not recur even without chemotherapy. On the other hand, it is difficult to determine which of these tumors will recur and to identify patients who would benefit from adjuvant chemotherapy after surgery. Tie et al. show that the presence of circulating tumor DNA in a patient's blood after surgery is a sign of persistent tumor and a greatly increased risk of relapse, suggesting that this group of patients may require chemotherapy to prevent recurrence. Detection of circulating tumor DNA (ctDNA) after resection of stage II colon cancer may identify patients at the highest risk of recurrence and help inform adjuvant treatment decisions. We used massively parallel sequencing based assays to evaluate the ability of ctDNA to detect minimal residual disease in 1046 plasma samples from a prospective cohort of 230 patients with resected stage II colon cancer. In patients not treated with adjuvant chemotherapy, ctDNA was detected postoperatively in 14 of 178 (7.9% patients, 11 (79% of whom had recurred at a median follow up of 27 months; recurrence occurred in only 16 (9.8 of 164 patients with negative ctDNA [hazard ratio (HR) 18; 95% confidence interval (CI) 7.9 to 40; P 0.001] In patients treated with chemotherapy, the presence of ctDNA after completion of chemotherapy was also associated with an inferior recurrence free survival (HR, 11; 95% CI, 1.8 to 68; P 0.001) ctDNA detection after stage II colon cancer resection provides direct evidence of residual disease and identifies patients at very high risk of recurrence.
Science Translational Medicine