In pursuit of alternative strategies to completion surgery for high-risk T1 colorectal carcinoma

Colorectal cancer (colorectal carcinoma) is being detected at an early stage (T1) more frequently, mainly due to the introduction of population screening programs. In most cases, the tumor can be removed by an endoscopic procedure. Previously, in the presence of risk factors, the advice was to perform additional bowel surgery – a major operation with risks for the patient. However, in 85-90% of patients, no residual tumor tissue was found. In this thesis, we have explored both how to predict who needs this surgery and alternative approaches when we cannot predict this reliably.
This thesis shows that we cannot rely on biopsies from the scar of the endoscopic excision to determine if there is residual tumor tissue. However, we have demonstrated that the margin for assessing the completeness of the removal can be narrowed, thereby reducing the number of patients undergoing unnecessary surgery. For patients with uncertainty regarding the risk of residual tumor tissue, an additional local removal of the scar can be performed. If no residual tumor is detected under the microscope, surgery can be avoided. For patients at higher risk of lymph node metastasis, who refrain from additional surgery after weighing the risks, the follow-up with endoscopy and scans showed significant variation. A uniform protocol has been created for this situation. Finally, this thesis shows that, looking back at a large group of patients who previously chose not to undergo surgery, compared to a group who did undergo additional surgery, the five-year survival rate is equal.