As reported in the Journal of Clinical Oncology by Taieb et al, a combined analysis of two phase III adjuvant trials (IDEA-France and IDEA-Greece) in stage III colon cancer showed that the presence of circulating tumor DNA (ctDNA) after surgery was prognostic for poorer outcomes and that Immunoscore (IS) provided prognostic information among patients without ctDNA.
Study Details
Samples were obtained after surgery and prior to the start of adjuvant therapy. Among the 554 patients with available ctDNA results, 445 (80.3%) had ctDNA-negative disease, and 109 (19.7%) had ctDNA-positiv disease. At baseline, T4/N2 disease and venous embolism, lymphatic invasion, and perineural invasion were more common in those with ctDNA-positive disease.
With a median follow-up of 6.7 years, the 2-year time to relapse rate was 43.5% (95% confidence interval [CI] = 34.1%–52.6%) among ctDNA-positive patients vs 88.1% (95% CI = 84.7%–90.8%) among ctDNA-negative patients (P < .0001).
On multivariate analysis, ctDNA was found to be an independent prognostic marker for time to relapse (adjusted hazard ratio [HR] = 5.21, 95% CI = 3.59–7.58, P < .001) and overall survival (adjusted HR = 4.84, 95% CI = 3.40–6.89, P < .001). ctDNA remained the most significant prognostic factor irrespective of disease stage, treatment duration, and IS results.
IS was not prognostic in ctDNA-positive patients. Among ctDNA-negative patients, IS-high remained prognostic for time to recurrence vs IS-intermediate and IS-low subgroups, with a statistically significant difference observed between IS-high and IS-low (HR = 3.67, 95% CI = 1.12–12.01, P = .02).
The investigators concluded: “In this combined analysis of two adjuvant trials dedicated to patients with stage III [colon cancer] after surgery, ctDNA was detectable in 19.7% of the patients and was confirmed as a major independent prognostic biomarker. IS seems to bring additional prognostic information in the 80.3% of patients who are ctDNA-negative.”
Julien Taieb, MD, PhD, of CARPEM Comprehensive Cancer Center, Georges-Pompidou European Hospital, Paris, is the corresponding author of the Journal of Clinical Oncology article.
Disclosure: The study was supported by the French INCa and Ministry of Health, Fondation ARC pour la recherche sur le Cancer, and others. For full disclosures of the study authors, visit ascopubs.org.
