MRI predicts increased eligibility for sphincter preservation after CRT in low rectal cancer

•MRIs were evaluated in rectal cancer patients assessing the feasibility of sphincter preservation.•Chemoradiation increases tumour distance to the anorectal junction.•Chemoradiation increases eligibility for sphincter preserving surgery in 21–25% patients.•MRI is valuable in the decision making for sphincter preservation after chemoradiation. Chemoradiation increases the eligibility for sphincter preservation in low rectal cancer, as assessed by MRI. We evaluated whether MRI can predict sphincter preservation after chemoradiation (CRT), and whether the feasibility of sphincter preservation increases after CRT, when compared with MRI before neoadjuvant treatment. 85 patients with low rectal tumour (≤5 cm from anorectal junction (ARJ)) were included. Radiologist and a surgeon measured the tumour distance to ARJ, and assigned confidence level scores (CLS) for the feasibility of sphincter preserving surgery on MRI. Reference standard was the type of surgery, sphincter preserving vs. non-preserving. Tumour distance from the ARJ increased after CRT by 9 mm (p