March is National Colon Cancer Awareness Month. Also called colorectal cancer, this is a cancer that begins in the colon (large intestine) or the rectum. Colorectal cancer is the third most common cancer in the United States and the second leading cause of cancer-related deaths. Most colorectal cancers start as abnormal growths in the lining of the colon or rectum called polyps. Over time, some polyps can turn into cancer.
“Colorectal cancer is a largely a preventable type of cancer,” says Brennan Scott, M.D., Chair of Gastroenterology at the Palo Alto Medical Foundation. “We have tests that detect many different types of cancer, but colon cancer can be prevented by doing a screening test to find polyps and removing them before they have a chance to become cancerous.”
According to the Centers for Disease Control and Prevention (CDC), at least 60 percent of deaths from colorectal cancer could be avoided by regular screening tests. At PAMF, the odds may be even better. New outcomes studies show that Dr. Scott and his team have surpassed national benchmarks for early tumor detection.
In this blog post, Dr. Scott answers common questions about colorectal cancer and explains how you can reduce your risk.
Who is at risk?
Colorectal cancer is most common in people over the age of 50 and the risk increases with age. Because of this, regular screening tests are recommended for average-risk people starting at age 50. People with a personal or family history of colorectal cancer or polyps, inflammatory bowel disease, or certain inherited genetic mutations may be at higher risk and should begin screening earlier. If you fit this description, talk to your doctor about when and how often to be tested, and what type of test is best for you.
What are the symptoms of colorectal cancer?
Precancerous polyps and the early stages of colorectal cancer often have no symptoms at all. This is why screening tests are so important. Signs and symptoms of later-stage colorectal cancer include:
- Altered bowel habits – including a change in stool consistency or frequency
- Blood in the stool
- Unexplained abdominal pain
- Unexplained weight loss
- Loss of appetite
- Anemia
What are the most common screening tests and how do they differ?
There are two general categories of screening tests: preventive tests that find both polyps and cancer and detection tests that primarily find cancer that has already formed.
Preventive tests include:
- Colonoscopy: The doctor uses a thin, flexible tube with a camera to examine the entire colon and remove any polyps that are detected. The procedure (which takes about 30 minutes) is usually performed under moderate sedation. Because colon must be empty so the doctor can see well, patients must “prep” by drinking a laxative before the test. The prep is generally considered the most unpleasant part of the test. However, if no polyps are found, colonoscopy typically needs to be performed only once every ten years.
- Sigmoidoscopy: Similar to a colonoscopy, but the doctor examines the only rectum and the lower third of the colon. Some bowel prep is required, and sedation is not routinely needed. It is used in conjunction with stool blood testing.
- CT Colonography: Also called a virtual colonoscopy, this a special type of CT scan. This test can detect larger polyps as well as cancer, although it may not detect smaller polyps. It is non-invasive, but a bowel prep must be still performed before the test, and the patient is exposed to some radiation.
Detection tests include:
- Stool Blood Tests: These tests look for tiny amounts of blood shed by colon tumors or large precancerous polyps. There are two types, one that uses a chemical to detect blood (FOBT or fecal occult blood test), and one that uses antibodies (FIT or fecal immunochemical test). Both tests work on stool samples taken at home, and no prep is required. However, they need to be repeated yearly, and can miss many polyps and some cancers.
- Stool DNA Test. This test looks for genetic material shed by cancer or polyp cells. It should be repeated every three years, and also can miss many polyps and some cancers.
How do I know which screening test is right for me?
A colonoscopy is the only test that can detect and remove the abnormal growths and has been proven to prevent colon cancer. However, if you have concerns, your gastroenterologist may individualize a screening program for you that may combine several testing methods. If any of those tests indicate the presence of polyps or cancer, your doctor will schedule a colonoscopy.
Is there anything I can do to reduce my risk of colorectal cancer?
The most effective way to reduce your risk is by having regular screening tests. However, certain lifestyle factors may also help decrease your risk, such as:
- Be physically active
- Maintain a healthy weight
- Eat a diet that is high in fiber and low in fat, especially animal fat
- Avoid tobacco and limit alcohol consumption.
The CDC estimates that as many as one-third of adults age 50 or older have not been screened as recommended. Colon cancer is a cancer you can prevent. Talk to your doctor today about high quality colonoscopy screening at PAMF.
Brennan Scott, M.D., is Chair of Gastroenterology at the Palo Alto Medical Foundation.
