Early detection of colorectal cancer: towards better surveillance

Abstract

Colorectal cancer (CRC) is a large health problem worldwide. In the Netherlands approximately 14.000 new cases are diagnosed each year. As such, colorectal cancer is the second most common type of cancer. The disease develops from precursor lesions, called polyps, which take an estimated 10 to 15 years to progress to cancer. During colonoscopy polyps can be detected and removed. If diagnosed in an early phase, colorectal cancer is often curable and the treatment burden limited. Those patients in whom colorectal cancer or advanced adenomas have previously been detected, are recommended to undergo regular follow-up colonoscopies. The monitoring of the increased risk population is called surveillance. In this thesis results have been generated that contribute to the improvement of the surveillance strategy for early detection of colorectal cancer. On the one hand, molecular changes have been studied that are associated with the progression from polyp to cancer. By understanding better which changes in a polyp will eventually lead to cancer, we may be able to better predict in the future who does and who does not need colonoscopies. On the other hand, alternative surveillance strategies have been tested in clinical practice. Instead of surveillance by colonoscopy, for example stool tests could be used to select patients with a high risk of colorectal cancer or advanced polyps. With the new insights presented, we will hopefully get closer to the implementation of new surveillance strategies that reduce the number of unnecessary colonoscopies and increase the cost-effectiveness of the surveillance programme.