PAEA Surgery End Of Rotation (EOR) Practice Exam

Colorectal carcinoma is most commonly found in which part of the colon?

1. Ascending and transverse colon

2. Descending and sigmoid colon

3. Cecum and rectum

4. Rectum only

The correct answer is: Descending and sigmoid colon

Colorectal carcinoma typically manifests most frequently in the descending and sigmoid colon. These areas are particularly common sites for the development of cancers due to factors such as higher exposure to carcinogenic substances in feces, the slower transit time of stool in these regions, and the abundant presence of lymphoid tissue which can be involved in oncogenesis. The descending colon, which transitions from the transverse colon to the sigmoid colon, and the sigmoid colon itself, which leads to the rectum, are frequently implicated in the formation of adenomatous polyps, which are precursors to colorectal cancer. While colorectal cancer can indeed develop in various segments of the colon, the prevalence in the descending and sigmoid areas is established through epidemiological studies. The cecum and rectum are also common sites but are not as prevalent collectively as the sigmoid and descending colon when considering overall occurrences.