Straight from the expert: how to understand your risk for colorectal cancer
Among adults, colorectal cancer is the third most common cancer in the United States. It is also the second most common cause of cancer-related deaths every year.
Fortunately, the overall prognosis, or likely outcome, is quite favorable if colorectal cancer is discovered early. Up to 90 percent of patients whose colorectal cancer is diagnosed and treated in the early stages can be cured.
Most colon and rectal cancers begin as adenomas, or small polyps, that can progress over time and invade the wall of the bowel. In their later stages, colon and rectal cancer cells can spread to other parts of the body.
Risk factors for colorectal cancer
Roughly 75 percent of colorectal cancers occur in people who have an average risk of developing the disease. This means they aren’t suffering from any gastrointestinal conditions or have a family history of colorectal cancer, but may have certain lifestyle risk factors. The following factors have been identified to increase risk.
- Age: Most people diagnosed with colorectal cancer are over the age of 50. However, in recent years there has been an increase in the number of people under 50 being diagnosed.
- Alcohol use: Moderate to heavy alcohol use has been linked to colorectal cancer. For people who drink alcohol, suggested limits are two drinks per day for men and one drink per day for women.
- Smoking: People who smoke have increased risk for developing both colorectal cancer and colon polyps.
- Personal history: People with a history of colorectal polyps or colorectal cancer (even if it was completely removed) have a higher risk of developing colon or rectal cancer.
- Inflammatory bowel disease (IBD): Chronic inflammatory diseases of the colon, such as ulcerative colitis or Crohn's disease, can increase the risk of colorectal cancer.
- Family history of colorectal cancer: First-degree relatives of people with colorectal cancer are at increased risk of developing cancer themselves. This is why it's important to know your family history.
- Inherited colorectal cancer syndromes: Genetic syndromes, such as familial adenomatous polyposis (FAP) and hereditary nonpolyposis colon cancer (HNPCC), are present in some families and can increase the risk of colon cancer.
- Racial/ethnic background: Black Americans have a higher incidence of colorectal cancer compared to other groups in the United States.
- Lifestyle factors: A diet high in fat and low in fiber, as well as obesity, can increase the risk for colorectal cancer.
Types of colorectal cancer screening tests
Since the early 1980s, the death rate from colorectal cancer has decreased steadily in the United States. In large part, these declines can be attributed to increased awareness and screening. However, recent data show that one in three adults between the ages of 45 and 75 is not up to date on recommended colorectal cancer screening.
There are several different types of screenings available for people of average risk. Be sure to ask your health-care provider which type might be right for you.
Colonoscopy
Colonoscopies are perhaps the most common procedure for colorectal cancer screening. A colonoscopy is typically performed by a gastroenterologist using a slender, flexible tube with a light and a video camera on the end that allows the doctor to review the entire colon. The procedure is painless and typically takes about a half hour. It is recommended every 10 years and traditionally for adults starting at age 45. However, if you are known to be at risk for colon cancer, your doctor may want you to consider a colonoscopy at a younger age.
CT colonography
Also known as a virtual colonoscopy, a CT colonography uses a series of X-rays to provide a detailed view of the inside of the colon. It requires the same bowel preparation as a colonoscopy and, if used, is recommended every five years.
Stool-based tests
- High-sensitivity guaiac fecal occult blood test (gFOBT) checks for blood in three consecutive stool samples. Recommended annually and often performed at home.
- Fecal immunochemical test (FIT) uses antibodies to detect blood in the stool. Recommended annually and only requires one stool sample.
- Stool DNA test (sDNA-FIT) detects altered DNA (blood) in the stool. Recommended every one to three years.
Flexible sigmoidoscopy
Flexible sigmoidoscopy is an exam that evaluates the lower part of the colon using a flexible tube with a tiny video camera at the tip. If necessary, the doctor may also perform a biopsy during this procedure. This exam is recommended every five years.
No matter what screening method you choose—with guidance from your health-care provider—early detection is key when it comes to colorectal cancer. And most importantly, it could save your life.