Marcee is a 52-year-old woman who worked at a reception desk at a company head office. She took some time off when she was treated for colorectal cancer

Question

The Dukes classification was stage I, and the treatment protocol involved surgery and radiation therapy. No one in her family had a history of the disease. Marcee does not drink or smoke, but she does not pay close attention to her diet. At work, her meals consisted mainly of the foods she got from vending machines at the cafeteria. At home, she preferred to heat up frozen dinners or any prepackaged food that required minimal preparation time.

Review Marcee's diet. What factors in her dietary choices might contribute to the development of colorectal cancer?

Colorectal cancer often arises from adenomatous polyps. What are the development and histological features of these polyps?

Colorectal cancer may be a complication in individuals with ulcerative colitis. How are the "pseudopolyps" seen in this disease different from the polyps discussed above?

Why is a fecal occult blood test used as one of the screening tools for colorectal cancer? Explain the procedure for administering the test.

Answer 1

Marcee's diet is high in refined foods. It is likely these food choices are low in the antioxidant vitamins A, C, and E that are necessary for neutralizing free radicals in the body. These foods are typically low in fiber, which acts to bulk up stool volume and assist in removing potential carcinogens from the bowel. A diet high in refined sugar encourages the proliferation of intestinal bacteria that are responsible for converting bile acids to carcinogens. Refined foods that are high in fat stimulate the increased synthesis of bile acids in the liver, providing a greater means for the production of carcinogens by bacteria.

Adenomatous polyps arise when the crypt cells of the intestinal epithelium proliferate in excess of what is needed to replace the cells that normally are shed from the mucosal surface. The cells that produce polyps proliferate in the base of the crypt, continue to replicate at the crypt surfaces (instead of becoming senescent), and express altered apoptosis after arriving at the surface of the epithelium. The changes in cellular differentiation can lead to dysplasia and the development of colorectal cancer.

In ulcerative colitis, inflammatory lesions develop in the crypts of Lieberkühn. Focal hemorrhages emerge that in turn suppurate to form crypt abscesses. The abscesses undergo necrosis and ulcerate. The inflammatory progression eventually produces projections of mucosal tissue that, because they resemble polyps, are termed pseudopolyps.

Because colorectal cancer causes intermittent intestinal bleeding, a fecal occult blood test may be used in conjunction with other screening tests to determine the presence of cancer. The patient is instructed to avoid vitamin C supplements, citrus fruits, and red meat for 3 days before the test to reduce the risk of false-positive results. NSAID use is halted 7 days before administering the test. The process using the guaiac-based test involves the preparation of two fecal slides from three consecutive bowel movements. The results are easy to obtain and can be assessed at the site of the health care provider.