CEACAM5 and colorectal cancer: Only a few studies to date have reported on combined analysis of pTN, ctDNA, and CEA for the prognosis of colorectal cancer.8,12,13 In surveillance strategies, a combination of CEA and imaging has been reported as efficient as ctDNA in detecting relapses.13 In a Danish and Spanish study evaluating ctDNA follow-up in 168 patients with stage 3 cancers, positive ctDNA was reported as the main prognostic factor.