COLORECTAL CANCER   29A

A 54-year-old man presents to the clinic for a routine checkup. He is well with no physical complaints. The history is remarkable only for a father with colon cancer at age 55 years. Physical examination findings are normal. Cancer screening is discussed, and the patient is sent home with fecal occult blood testing supplies. The fecal occult blood test results are positive. Subsequent colonoscopy reveals a villous adenoma as well as a 2-cm carcinoma.

What are the salient features of this patient’s problem? How do you think through his problem?

Salient features: Family history of colon cancer at similar age; routine screening after age 50 years; positive fecal occult blood test result; subsequent colonoscopy with both an adenoma and a carcinoma

How to think through: What are the recommended colon cancer screening modalities? When does screening start for a patient with no family history of polyposis or colon cancer? When should screening have begun for the patient in this case? (10 years earlier than the age at which his father was diagnosed.) What pathological characteristics of polyps found on colonoscopy are considered high risk for progression to cancer? (Tubular adenoma, villous adenoma.) In addition to family history, what are the other known risk factors for colon cancer? (Inflammatory bowel disease; diets low in fiber and high in red meat and fat; black > white race.) How does right-sided colon cancer present? How does left-sided colon cancer present? What is the next step for this patient? (Computed tomography [CT] scan of the chest, abdomen, and pelvis for preoperative staging.) For which stages of colon cancer is chemotherapy a recommended part of the treatment?

COLORECTAL CANCER   29B

What are the essentials of diagnosis and general considerations regarding colorectal cancer?

Essentials of Diagnosis

Personal or family history of adenomatous polyps or colorectal cancer are important risk factors

Symptoms or signs depend on tumor location; proximal colon cancer causes fecal occult blood and anemia, distal colon cancer causes change in bowel habits and hematochezia

Diagnosis established with colonoscopy

General Considerations

Second leading cause of death from malignancy in the United States

Many adenocarcinomas (∼50%) occur within reach of detection by flexible sigmoidoscopy

Most colorectal cancers arise from malignant transformation of an adenomatous polyp (tubular, tubulovillous, or villous adenoma) or serrated polyp (traditional serrated adenoma, or sessile serrated adenoma)

Up to 5% are caused by polyposis syndromes or hereditary nonpolyposis colorectal cancer

Risk factors include older age, personal or family history, inflammatory bowel disease (ulcerative colitis and Crohn colitis), high-fat and red meat diets, and race (blacks > whites)

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