Circulating cell-free DNA as predictor of pathological complete response in locally advanced rectal cancer patients undergoing preoperative chemoradiotherapy

•cfDNA could be a biomarker for tailored follow-up in locally advanced rectal cancer.•Circulating cell-free DNA can be quantified by a rapid, and feasible DFA method.•Low cfDNA levels at end of therapy were related to pathological complete response.•‘cfDNA responders’ with descending levels during therapy were associated with pCR.•We propose cfDNA as a complimentary tool for patient selection for a W&W strategy.