To Örebro University

Introduction: Rectal cancer has historically been treated with resection surgery. (Chemo)radiotherapy results in a clinical complete response (cCR) in some patients, which enables a nonoperative management; “watch and wait”. Low Anterior Resection Syndrome (LARS) is a consequence after sphincter-preserving surgery, however similar symptoms can occur after treatment with (chemo) radiotherapy. The aim of this study was to report the prevalence of LARS in Swedish patients treated as watch and wait within a research protocol and to identify trends over time.

Method: The WoW study is a multicenter prospective national cohort study including patients with cCR after (chemo)radiotherapy for rectal cancer. The study population consists of 211 patients with stage I-III rectal cancer and cCR included between January 2017 and February 2023. LARS-score was analyzed at baseline, six months and one year.

Result: Demography and clinical characteristics are presented in the table. Questionnaires were available for 182 patients in total. LARS-score was possible to analyze for 170 patients at baseline, 136 at six months and 118 at one year, patients reporting a stoma wereexcluded. Major LARS was reported by 41 (24%) patients at baseline, 35 (26%) at 6 months and 26 (22%) at 12 months.

Discussion: One of four patients in this WoW-cohort reported major LARS and it is persistent after one year. Long-term follow-up is required to see if symptoms change over time to understand the functional outcome of the treatment offered to be able to provide adequate information about possible long-lasting life changes due to treatment.