Colorectal cancer is the third most common type of non-skin cancer for both men (after prostrate and lung) and women (after breast and lung cancer). It is the second leading cause of cancer death in the United States after lung cancer. The cancer society estimates that in 2018, more than 97,000 Americans will be diagnosed with colon cancer and more than 43,000 will be diagnosed with rectal cancer. About 50,000 people are expected to die of colorectal cancer this year.
The rates of new colorectal cancer cases and deaths among adults aged 50 years or older are decreasing in this country due to an increase in screening and changes in some risk factors, such as a decline in smoking. However, incidence is increasing among younger adults for reasons that are not known. Since 1994, there has been a 51% increase in the rate of the disease among those younger than 50. Researchers predict that by 2030, based on current U.S. trends, colon cancer incidence rates will increase by 90% for people aged 20 to 34 years and by 28% for people aged 35 to 49 years, whereas they will decrease by 38% for people aged 50 to 74 years and by 45% for those 75 years or older.A recent analysis found that adults born around 1990 have twice the risk of colon cancer and four times the risk of rectal cancer, compared with adults born around 1950. As they age, younger adults will continue to have an elevated risk, compared with previous generations, studies suggest. The American Cancer Society, responding to a rise in colorectal cancer rates among younger people, now recommends that adults undergo screening for the disease beginning at age 45 rather than 50. It is believed the rise in colorectal cancer is possibly due to increasing rates of obesity, a lack of exercise, and the consumption of processed foods. The organization announced the change in its guidelines in June of this year after extensive analysis showed that lowering the starting age for screening would save lives. The recommendations apply to adults who are at average risk of the disease; this includes most people in the United States.
There is adequate evidence that moderate dairy consumption, reduced red meat consumption, increased physical activity, and decreased body mass index all decrease the risk of colorectal cancer and adenomatous polyps. Increased alcohol intake and tobacco use are associated with an increased risk of colorectal cancer. Anyone experiencing persistent and concerning gastrointestinal symptoms should seek out medical care. Signs of colorectal cancer may include a change in bowel habits, such as diarrhea or constipation, that lasts more than a few days, rectal bleeding, cramping, or abdominal pain.
The best way to detect and find cancers early is through screening tests. Tests are used to look for a disease when a person doesn’t have symptoms. Diagnostic tests are used when symptoms are present. Colorectal cancer almost always develops from precancerous polyps (abnormal growths) in the colon or rectum. Screening tests can find these polyp’s so they can be removed before becoming cancerous, when treatment works best. According to the CDC, those at higher risk for colorectal cancers require earlier screening tests. If any of the following factors are true for you, reach out to your provider:
• You or a close relative have had colorectal polyps or colorectal cancer.
• You have an inflammatory bowed disease such as Crohn’s disease or ulcerative colitis.
• You have a genetic syndrome such as familial adenomatous polyposis (FAP) or hereditary non-polyposis colorectal cancer (Lynch syndrome).
According to the National Institute for Health (NIH) screening tests include:
High-sensitivity fecal occult blood tests (FOBT): Both polyps and colorectal cancers can bleed, and FOBT checks for tiny amounts of blood in stool that cannot be visually detected (Blood in stool may also indicate the presence of conditions that are not cancer, such as hemorrhoids.). Studies have shown that FOBT, when performed every year in people aged 50 to 80 years, can help reduce the number of deaths due to colorectal cancer by 15 to 33%.
Stool DNA test (FIT-DNA): Currently the only stool DNA test approved by the FDA, Cologuard®, is a multitarget test that detects tiny amounts of blood in the stool as well as nine DNA bio markers in three genes that have been found in colorectal cancer and precancerous advanced adenomas. People who have a positive finding with this test are advised to have a colonoscopy. In one study of those at average risk of developing colon cancer and had no symptoms of colon problems, this test detected more cancers and adenomas than the above fecal occult blood test. However, the FIT-DNA test also was more likely to identify an abnormality when none was actually present. The American Cancer Society recommends testing every 3 years.
Sigmoidoscopy: In this test, the rectum and sigmoid colon are examined using a sigmoidoscope. The lower colon must be cleared of stool before sigmoidoscopy, but the preparation is less extensive than that required for colonoscopy. People are usually not sedated for this test. Studies have shown that people who have regular screening with sigmoidoscopy after age 50 years have a 60 to 70% lower risk of death due to cancer of the rectum and lower colon than people who do not have screening. One clinical trial found that even just one sigmoidoscopy screening between 55 and 64 years of age can substantially reduce colorectal cancer incidence and mortality. Experts generally recommend sigmoidoscopy every 5 years for people at average risk who have had negative test results.
Standard (or optical) colonoscopy: This is where the rectum and entire colon are examined after a thorough cleansing of the colon. Most patients receive some form of sedation during the test. Studies suggest that colonoscopy reduces deaths from colorectal cancer by about 60 to 70%. Experts recommend colonoscopy every 10 years for people at average risk as long as their test results are negative.
Virtual colonoscopy: This screening method uses a CAT scan to produce a series of pictures of the colon and the rectum from outside the body. A computer then assembles these pictures into detailed images that can show polyps and other abnormalities. Virtual colonoscopy is less invasive than standard colonoscopy and does not require sedation. As with standard colonoscopy, a thorough cleansing of the colon is necessary before this test. The accuracy of virtual colonoscopy is similar to that of standard colonoscopy, and virtual colonoscopy has a lower risk of complications. If polyps or other abnormal growths are found, then a standard colonoscopy is performed to remove them. Whether virtual colonoscopy can help reduce deaths from colorectal cancer is not yet known. Medicare and some insurance companies currently do not pay for the costs of this procedure. Studies are ongoing to compare virtual colonoscopy with other screening methods.
Double contrast barium enema: This is another method of visualizing the colon from outside the body. In DCBE, a series of x-ray images of the entire colon and rectum is taken after the patient is given an enema with a barium solution. The barium helps to outline the colon and the rectum on the images. This screening is rarely used because it is less sensitive than colonoscopy in detecting small polyps and cancers. However, it may be used for people who cannot undergo standard colonoscopy because they are at particular risk for complications.
Whatever screening method you choose, the results are indisputable- screening will pick up cancers early and save lives.
Main image courtesy of livescience.com