Colon cancer is a malignant growth on the lining of the large intestine that if left undetected or untreated can lead to cancer cell invasion of other vital organs.
Colon cancer is the 4th most commonly diagnosed cancer and the 2nd leading cause of cancer-related deaths in the United States. Each year 140,000 individuals are diagnosed with colon cancer and 50,000 will die from it.
Most colon cancers develop from adenomatous polyps. Screening for polyps in asymptomatic individuals and removing them leads to the prevention of colon cancer. A screening colonoscopy is now considered the preferred modality to search for polyps, early cancers or advanced cancers.
A colonoscopy offers the advantage of visualization of the entire colonic lining, and the ability of removing polyps or early malignant lesions. Currently, a screening colonoscopy is recommended every ten years for individuals over the age of 50 that are asymptomatic, with no family history of colon polyps or cancer.
When a patient comes to me and says "my father had colon cancer; when should I start my screening?" I ask my patient about the age of his father when he had the colon cancer. If the father was above the age of 60, I would recommend a colonoscopy every 10 years starting at the age of 40. But if my patient's father had "advanced adenoma" or colon cancer before the age of 60, I would recommend a colonoscopy every 5 years beginning at the age of 40 or 10 years younger than the age of diagnosis of the youngest affected relative.
What if two first-degree relatives had colon cancer or advanced adenoma? This indicates that the patient is high risk as well, and a colonoscopy should be done every 5 years beginning at the age of 40, or 10 years younger than the age of diagnosis of the youngest affected relative.
Let me mention briefly about the rule of 3:2:1. If 3 immediate relatives were found to have colon cancer that has spread over 2 generations, with one of the affected individuals being under the age of 50, this raises a big red flag that we are possibly dealing with an inherited form of colon cancer which requires earlier and much more frequent screenings as well as genetic testing.
Recent guidelines also recommend that the age of initial screening for African-American patients is 45 rather than 50.
Smoking and being overweight cause patients to be at high risk for colon polyps and colon cancer. However, recent guidelines do not recommend starting the screening before the age of 50.
Alternative screening strategies for patients who decline or are unable to have a colonoscopy include: Annual high-sensitivity fecal occult blood testing, or flexible Sigmoidoscopy every 5 years along with fecal occult blood testing of the stool every 2-3 years, and lastly Virtual colonoscopy every 5 years.