Project 466919

Colorectal cancer is the second cause of cancer deaths and the third most common cancer worldwide. The main screening modality is colonoscopy, a procedure where the bowel is visualized with a camera and where pre-cancerous lesions can be removed. Such screening has been proven to reduce medical complications and deaths from colorectal cancer. After pre-cancerous lesions are removed, physicians refer to society guidelines to decide when patients should be seen again. For example, patients with a normal colonoscopy should be seen in seven to ten years. One of the pre-cancerous lesions that can be found is high-grade dysplasia. Guidelines suggest that a patient who has high-grade dysplasia should have a repeat colonoscopy in three years, based on expert consensus, but that the evidence to support this recommendation is of low to moderate quality. One study found that this pre-cancerous lesion increases the risk of future colorectal cancer while three studies found that it does not. The goal of my project is to determine if high-grade dysplasia increases the risk of future colorectal cancer and of future pre-cancerous lesions. Other goals of my project are to determine how certain factors can affect this risk, like sex, age, obesity, smoking, alcohol use or colorectal cancer in the family, and to determine if patients received appropriate follow-up. 1235 patients will be included in the study. This makes it the largest study on high-grade dysplasia to date. We hypothesize that high-grade dysplasia truly increases the risk of future pre-cancerous lesions and colorectal cancer. This study will allow us to significantly contribute to the knowledge that physicians have on this pre-cancerous lesion, to be able to deliver better care to patients undergoing a colonoscopy.