ctDNA responds to neoadjuvant treatment in locally advanced rectal cancer.

Background: Liquid biopsy is a minimally invasive procedure investigating tumor mutations.

Methods: In our retrospective study, we investigated whether molecular therapy monitoring of patients receiving neoadjuvant radio(chemo)therapy on a daily routine is possible in 17 patients with locally advanced rectal cancer. Six patients received short-course radiotherapy (5 × 5 Gy) with subsequent surgery, six patients were treated according RAPIDO protocol with short-course radiotherapy followed by chemotherapy (FOLFOX4) and subsequent surgery and five patients received conventional neoadjuvant radiochemotherapy with 5-FU followed by surgery.