Among cancers that affect both men and women, colorectal cancer is the second leading cause of cancer deaths in the United States. Dr. Brooks Cash, professor of internal medicine at the University of South Alabama College of Medicine and a gastroenterologist with USA Physicians Group, said it doesn’t have to be.
“The primary messages that we need to communicate with regard to colon cancer are that colon cancer screenings save lives, average risk screening begins at age 50, and a menu of options in terms of colorectal screening tests is increasing.” Dr. Cash said.
A screening test is one that is used to look for a disease when a person does not have signs or symptoms. Colorectal cancer almost always develops from precancerous polyps (abnormal growths) in the colon or rectum. Screening tests can find precancerous polyps so that they can be removed before they become cancerous. Screening tests can also find colorectal cancer early, when treatment works best.
“Everybody should be screened for colon cancer, and early detection is key,” Dr. Cash said. “The earlier we find colon cancer, the better the likelihood is that somebody will actually be able to have the colon cancer successfully treated.”
When colon cancer is discovered early, the five-year mortality rate can be driven down to less than 5 percent, according to Dr. Cash. When colon cancer is discovered late – after it has spread to other organs of the body – the five-year survival is “quite dismal.”
“Our goal in screening is not to find cancer, though that does occasionally occur, but rather the goal of screening is to find and remove precancerous polyps before they can develop into cancer,” Dr. Cash said. “We want to prevent the cancer. That’s why colonoscopy, especially, is considered the gold standard among the various recommended tests for colon cancer screening and prevention.”
Colonoscopy is a procedure in which a trained specialist uses a flexible, narrow tube with a light and tiny camera on one end, called a colonoscope, to look inside your rectum and colon.
If you are 50 or older, Dr. Cash said you should be talking to your primary care provider about colon cancer screening. If you have a family history of colon cancer or if you have any symptoms – such as unintentional weight loss, abdominal pain, changes in bowel habits or if you notice blood in your bowel movements – then you should speak to your primary care physician even earlier.
Dr. Cash said colon cancer risk is broken down into high risk individuals and low risk or average risk individuals, with the average risk of developing colon cancer during one’s lifetime (without screening) of about 6 percent. However, there are individuals who are at an increased risk. That includes people who have a family history of colon cancer – such as a first-degree relative (a sibling or parent) or multiple second-degree relatives (grandparent or uncle). Screening with colonoscopy has been estimated to dramatically reduce the risk of developing colon cancer, perhaps by as much as 75-80 percent.
The other area of increased risk is in patients who have a genetic colon cancer syndrome, which accounts for approximately 5 percent of colon cancers. This includes conditions such as Lynch syndrome and familial adenomatous polyposis (FAP). Those with FAP are recommended for a screening as early as the adolescent years, and individuals with lynch syndrome are recommended for screening in the mid-20s.
Those with inflammatory bowel diseases such as ulcerative colitis and Crohn’s disease also carry a higher risk of colon cancer due to chronic inflammation. Dr. Cash said these patients are recommended to undergo colonoscopy earlier and more frequently than average risk patients.
According to Dr. Cash, there are lifestyle modifications that may reduce the risk of developing colon cancer. “It is important to maintain an ideal body weight by increasing physical activity, to limit alcohol consumption and to avoid tobacco use,” Dr. Cash said. Research is underway to find out if changes in diet can reduce the risk of colorectal cancer. There is also data that suggests that certain medicines and supplements – including low-dose aspirin, calcium and vitamin D – may reduce the risk of colon cancer.
Exactly how these supplements might reduce the risk of colon cancer remains poorly understood, and the data that supports the use of such supplements suggests only a modest degree of protection after several decades of use. “I certainly endorse the use of aspirin, calcium, and vitamin D when clinically appropriate for general health maintenance,” Dr. Cash said, “but I would recommend against relying on these therapies to result in a clinically meaningful reduction in colon cancer risk. They should not be used as a substitute for a high quality screening examination.”
In addition, Dr. Cash said there is equivocal data regarding the benefit of fiber for reducing the risk of colorectal cancer. “While there is little downside to a high fiber diet, it should not be relied upon to meaningfully reduce the risk of colon cancer,” he said. “The best form of fiber is soluble fiber, such as psyllium, as opposed to crude fiber such as bran. One of the most common side effects to fiber is bloating.”
Overall, Dr. Cash emphasized that the most effective way to reduce your risk of colorectal cancer is by having regular colorectal cancer screening tests beginning at age 50, or sooner if you have an increased risk. While the most widely recommended screening test is colonoscopy, other less invasive options exist. These include testing the stool for blood, evaluating the DNA in stool to detect abnormal genes and proteins associated with colon cancer, a radiologic test known as “virtual colonoscopy,” and most recently a swallowed camera housed within a capsule that is designed to examine the colon as it moves through the gastrointestinal tract.
“These latter two tests are currently indicated for patients who are unable to tolerate or complete a colonoscopy,” Dr. Cash said, “but they have great promise for the future. The Gastroenterology Division at USA recently acquired the Colon Capsule device, and we work closely with our radiology colleagues on the virtual colonoscopy. We are expecting these colonoscopy alternatives to play a larger role in our screening efforts in the future.”
Dr. Cash said it is important to realize that these alternative tests, if positive, should result in referral for colonoscopy in order to determine why they were positive.
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