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. 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 (Chapter 37, Learning Objective 9).
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 histologic 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.
Full Answer Section
Histologically, adenomatous polyps can be classified into different types, including tubular adenomas, villous adenomas, and tubulovillous adenomas. Tubular adenomas are the most common type and are generally considered less likely to progress to cancer. Villous adenomas, on the other hand, have a higher risk of malignant transformation.
Pseudopolyps vs. Adenomatous Polyps
Pseudopolyps are inflammatory polyps that can develop in the colon of individuals with ulcerative colitis. Unlike adenomatous polyps, they are not precancerous lesions. They are formed as a result of chronic inflammation and ulceration of the colonic mucosa. While pseudopolyps can be associated with an increased risk of colorectal cancer, their pathogenesis is different from that of adenomatous polyps.
Fecal Occult Blood Test
A fecal occult blood test (FOBT) is a simple screening test for colorectal cancer. It detects hidden blood in the stool, which may indicate the presence of polyps or cancer.
Procedure:
- Stool Collection: The patient collects a small sample of stool on a special card provided by the healthcare provider.
- Guaiac Test: The stool sample is mixed with a chemical reagent that turns blue if blood is present.
- Interpretation: A positive test result indicates the presence of blood in the stool, which may warrant further investigation, such as colonoscopy.
Regular screening with FOBT is recommended for individuals over the age of 50 to detect colorectal cancer early, when it is most treatable.
Sample Answer
Dietary Factors Contributing to Colorectal Cancer
Marcee's dietary habits may have contributed to her risk of developing colorectal cancer. A diet high in processed foods and low in fiber can increase the risk of colon cancer. Her reliance on vending machine snacks and pre-packaged meals likely limited her intake of fruits, vegetables, and whole grains, which are essential for maintaining a healthy gut.
Development and Histologic Features of Adenomatous Polyps
Adenomatous polyps are benign growths in the colon or rectum that can develop into cancer over time. They arise from abnormal cell growth in the lining of the colon. The progression of adenomatous polyps to cancer involves a series of genetic mutations that lead to uncontrolled cell proliferation.