With the introduction of the national screening program for colorectal cancer (CRC), the detection rate of early-stage CRC (T1 CRC) is expected to increase to approximately 40% of all screening detected cancers. The vast majority of patients with T1 CRC can potentially be curatively treated with endoscopic resection. However, 8-13% of patients have lymph node metastasis at time of diagnosis. These are the patients that benefit from (additional) surgery, which maintains a higher complication and mortaliy rate, and is associated with higher healthcare costs. However, it is difficult to identify these patients prior to major surgery. Current histological criteria have a positive predictive value of 15% and a negative predictive value of 100%, causing that 85% of patient undergo a resection without any benefit. In daily clinical practice it therefore remains difficult for both patients and doctors to make a decision for the appropriate treatment.

Due to lack of good evidence, current guidelines are not able to properly guide practice on diagnosis, choice of treatment modality, prognosis and personalized surveillance of patients with T1 CRC.

This has motivated a group of hospitals to collaborate to increase the quality of research on this topic. In 2014, the Dutch T1 CRC Working Group was founded. Currently, more then 20 hospitals participate in the Dutch T1 Working Group. With this multidisciplinary multicenter collaboration we aim to perform high-quality research concerning the detection, differentiation, choice of treatment and surveillance of T1 CRC in order to increase common knowledge and awareness and decrease the number of future patients that will be referred for surgery without any benefit.