How to Diagnose and Treat Colon Cancer for the Physician Assistant Exam
Colon cancer is a topic you’ll surely be asked about on the Physician Assistant Exam (PANCE), because colorectal cancer is the third most commonly diagnosed cancer in males and the second in females, especially in developed countries.
Watch for risk factors
Risk factors for colon cancer include a low-fiber Western diet, inflammatory bowel disease, and heredity. A big hereditary condition that you should be aware of is familial adenomatous polyposis (FAP). With this condition, you see many polyps throughout the colon, and the incidence of cancer is very high. Most people with familial adenomatous polyposis will develop colon cancer before age 40. The treatment for FAP is a colectomy.
Signs, symptoms, and treatment of colon cancer
Signs and symptoms of colon cancer can include bleeding and abnormalities of bowel habits, including constipation and diarrhea. If the tumor is large enough and much of the colonic lumen is obstructed, then symptoms of obstruction, including abdominal pain, distention, nausea, and vomiting, may be present.
On a colonoscopy, you may see a polyp. Different types and different characteristics of polyps can imply a benign or a malignant prognosis. For example, hamartomatous polyps are completely benign.
If the polyp is a tubular adenoma, it has a low risk of malignancy, but it still has a malignancy risk. If a villous adenoma is present, it has a very high malignancy potential. Any polyp with a sessile base has a higher risk of developing into cancer.
Here are three essential points about colon cancer:
The most common site of metastasis is the liver.
Therapy can include surgery and chemotherapy. Common chemotherapeutic agents used in the treatment of colon cancer include 5-fluorouracil (5-FU) and certain platinum-based compounds, including oxaliplatin. A main side effect of 5-FU is diarrhea — very significant diarrhea.
After the colon cancer is diagnosed, you use the carcinoembryonic antigen (CEA) level to monitor recurrence and response to therapy.
Screening for colon cancer
The PANCE is likely to ask about when someone should be screened as well as risk factors for colon cancer. This is a big topic, so expect big questions. Someone who has no family history of colon cancer should begin the following screening tests for colon cancer at age 50 (note that the current guidelines talk about screening until age 75):
A colonoscopy every 10 years
A sigmoidoscopy every 5 years (Barry considers this to be “colonoscopy light”)
Annual fecal occult blood testing (FOBT)