Final answer:
Colorectal carcinoma is most common in the sigmoid and rectum regions of the colon. Adenocarcinoma accounts for 95% of primary colon cancers.
Step-by-step explanation:
Colorectal carcinoma is most common in the sigmoid and rectum regions of the colon. The sigmoid colon is the S-shaped part of the large intestine that connects to the rectum. It is the most common site for colorectal cancer. Adenocarcinoma accounts for 95% of primary colon cancers. Adenocarcinoma is a type of cancer that starts in the cells that line the inside of the colon and rectum.