ABSTRACT
Protective factors against colorectal cancer include the following:
l Increased dietary fiber l Reduced animal fat intake l Supplements of vitamin D l Folate and antioxidants such as vitamin E
Histopathology Most colorectal cancers are moderately well differentiated gland-forming adenocarcinomas. Less common cell types include signet ring adenocarcinoma (see “Linitis Plastica” in “Pitfalls of MRI” section), adenosquamous carcinoma, squamous cell carcinoma, small cell carcinoma, choriocarcinoma, and medullary cell carcinoma. Colorectal carcinoid tumors occasionally occur (more commonly in the rectum) and arise in the submucosa. Sarcomas (usually leiomyosarcoma) are rarer, comprising up to 0.3% of colorectal tumors.
