Colorectal cancer is a cancer that develops in the large intestine or rectum. In New Hampshire, about 35 out of 100,000 people develop this cancer each year. Both the incidence and mortality from this cancer have decreased 3% over the last decade. Around 75% of 50 to 75 year old people in New Hampshire are up to date with getting screened. Catching the cancer early means less extensive treatment is needed. Even better, detecting precancerous polyps can prevent the development of colon cancer.
Symptoms of colorectal cancer include bright red rectal bleeding, black tarry stools, unexplained anemia, abdominal pain, weight loss, change in bowel habits (diarrhea or constipation, change in size or caliber of stools), tenesmus (feeling of incomplete emptying) and rectal pain.
All adults should undergo colon cancer screening starting at age 50 or earlier, depending on their risk of developing this cancer. The optimal screening depends on your preferences and risk of developing colon cancer. Let’s review the types of screening tests available.
The simplest, least invasive, least expensive, but not necessarily the most effective, test is screening the stool for blood. These stool cards (called guiaic tests) are designed to detect microscopic amounts of blood in the stool. Once a year guiaic testing reduces the risk of dying from colorectal cancer by up to one-third. But, because polyps seldom bleed, they are not likely to pick them up. Also, only 2 to 5% of people with a positive stool test actually have colon cancer. A positive guiaic test should be followed by a colonoscopy to check for cancer or polyps.
Colonscopy involves using a thin, lighted tube to directly see the lining of the rectum and large bowel. Your colon needs to be “cleaned out”, ie, prepped, by consuming medication that causes diarrhea. You receive a mild sedative drug before the procedure. Polyps and some cancers can be removed during the procedure. Colonoscopy detects most small polyps and all large polyps and cancers, and greatly reduces your risk of developing and dying from colon cancer. Disadvantages are the cost, the inconvenience of the prep, and the small risk of having serious bleeding or a tear in the colon wall during the procedure. Because the procedure requires sedation, you will need someone to drive you home afterwards, and you should not plan to return to work the day of the test.
What about virtual colonoscopy – will this test save you from the discomfort of having colonscopy? This test uses a CT scanner to take images of the entire bowel, and the 2- and 3-D images allow the radiologist to see if polyps or cancer is present. Its advantages are that it does not require sedation, is noninvasive, the entire bowel can be checked, and polyps are found about as well as with regular colonoscopy. But, you have to “prep” your bowel just like for the regular test, and it exposes you to radiation that may have long term effects. If abnormal areas are seen, you will need to have “real” colonoscopy to check them out and take a tissue sample (biopsy). Virtual colonscopy may also find abnormalities other than polyps or cancer, and these may require further testing. Also, not all insurance companies cover this test. So, virtual colonscopy may not be the answer to your prayers to avoid regular colonscopy.
People with an average risk of colon cancer should begin screening at age 50. Colonscopy can be done every 10 years, unless something is found that requires follow up sooner. “Virtual” colonscopy can be performed every 5 years. Stool testing every year is your other options.
For those at increased risk of colorectal cancer, screening may need to start at an earlier age, occur more frequently, and include colonoscopy as a higher priority test. People with a first degree relative (parent, sibling or child) with colorectal cancer or adenomatous polyps before the age of 60 should begin screening at age 40 or 10 years younger than when their relative was diagnosed. Colonoscopy, repeated every 5 years, is recommended. Some families have genetically based colon cancer syndromes , such as familial adenomatous polyposis (FAP) or hereditary nonpolyposis colon cancer (HNPCC or Lynch syndrome). People with this family history need aggressive screening and are best managed by a physician with clinical expertise in these syndromes. People with inflammatory bowel disease (ulcerative colitis or Crohn’s disease) also are at increased risk, with screening dependent on how much of the bowel is involved and how long they have had the disease.
So, remember that everyone who has a colon is at risk of colorectal cancer and get screened!
Dr. Diane Arsenault, MD, FAAFP, HPM, HMDC
Family Medicine, Mid-State Health Center