Towards minimal invasive treatment of T1 colorectal cancer

The widespread implementation of CRC screening programs has led to an increase in the detection of T1 CRCs. For decades, oncologic surgery has been the cornerstone of treatment for T1 CRC. About 7-12% of T1 CRCs harbor lymph node metastasis (LNM). Oncologic surgery enables resection of the draining lymph nodes, hereby aiming to prevent potential further spread of LNM to distant organs. However, colorectal surgery is associated with a considerable morbidity and mortality risk. Moreover, even after surgery there is still a risk that the patient will develop metastasis. Growing evidence, mostly from Asian studies, shows that minimal invasive endoscopic resection might be an alternative treatment for a subset of T1 CRCs. These endoscopic resection methods are associated with a considerable lower complication and mortality rate, and substantially lower healthcare costs. However, no good prediction rule exists to adequately determine the risk for LNM in T1 CRC. Moreover, as a result of diagnostic difficulties in optical diagnosis as well as the technical challenges of achieving an en-bloc resection, to date only approximately 19-25% of patients with T1 CRC are treated with endoscopic resection. The multidisciplinary research reported in this thesis aims to increase knowledge on the diagnosis and treatment of patients with T1 CRC, with the goal to decrease the high proportion of T1 CRC patients currently referred for surgery whereas they could have been treated with local minimal invasive resection