SUBJ: colonoscopy0
https://nutritioninvestigator.org/colonoscopy/
SHORT NOTE:
Colonoscopies can be done with a variety of techniques. If you have concern, you should start at age 45. The standard colonoscopy involves drinking a liquid the night before that purges your colon through a lot of defecating. I did it once, but will not do it again. There is evidence it gives many false positive results requiring unnecessary surgery, and lots of false negative results where cancer is likely but detected. There is now an at-home test where you collect and mail in a fecal sample, and also a blood test that is possible.
LONG NOTE:
According to the American Cancer Society, colon cancer is an abnormal growth of cells in the colon or rectum that can invade nearby tissues or spread to other organs. Normally, colon cancer starts as a polyp (small growth) that gets larger over time. While not all polyps are cancerous, some do turn into cancer, which is why getting screened is so important.
The American Cancer Society recommends that people at average risk for colorectal cancer get their first colonoscopy at age 45. If no polyps are found, you should wait 10 years before getting another colonoscopy.
What kind of colonoscopy is useful as of 2024?
The type of colonoscopy you should get depends on your individual circumstances, such as your age, family history, and medical history. You should talk with your health care provider about which test is best for you. Here are some types of colonoscopies:
- Traditional colonoscopy
Involves inserting a scope into the colon. The day before, you’ll need to drink a liquid to empty your bowels.
- Virtual colonoscopy
Also known as a CT colonography, this procedure uses a CT scan to create images of the colon and rectum. It doesn’t require sedation or inserting a scope into the colon.
- At-home test
A quick and effective option if you can’t take time off work, are afraid of sedation, or are not at increased risk. However, at-home tests can produce false-positive and false-negative results.
[Note this was before the blood test for colon cancer was developed in 2024. Colon Cancer Screening Test – Colon Blood Sample Test]
The American Cancer Society recommends that most people start screening for colon cancer at age 50. If you have a family history of colon cancer or are at high risk, you may need to start screening earlier. Other types of colorectal cancer screening tests include flexible sigmoidoscopy and stool tests.
There has been a lot happening with colonoscopy technology, worth discussing with your doctor if they are experts.
Roc had a colonoscopy when he turned 50, a horrible ordeal. About 3 years ago (2004), he heard on NPR that traditional colonoscopies (COL) like that were no longer worth doing. They reported that 50% of COL give false positive results, requiring followup surgery for polyps that are not cancerous, and 50% of COL miss polyps that actually are cancerous. So he resolved not to have one again. He has relied on the stool sample at home method since then, even though his first cousin died of colon cancer.
Concern about my colonoscopy post from a reader: I hate to say this but I think your Point 1 summary [Blood test for colorectal cancer for those over 45 with average risk for disease more accurate than colonoscopy.] is inaccurate. If I am reading the article correctly, the blood test is more accurate than a stool sample, but not quite as good as a colonoscopy. See below excerpted from the article on the test. The reason I was so interested in it is my wife is extremely reluctant to get a colonoscopy. Hence, if there is something else out there that would be as good or better, we would be thrilled. I do hope all is well and that you keep this wonderful information coming!
Of the 7,861 people included in the NEJM report, 83.1% of the participants with colorectal cancer confirmed by colonoscopy had a positive blood test for ctDNA and 16.9% had a negative test — in which a colonoscopy showed colorectal cancer but the ctDNA test did not. The test was most sensitive for colorectal cancers, including early stage cancers, and was less sensitive for advanced precancerous lesions, which can turn into cancer over time.
Grady said that the sensitivity of the blood test for colorectal cancer is similar to stool-based tests and lower than that of colonoscopy, which he still considers the most accurate screening test for colorectal cancer.
“Colorectal cancer is common and very preventable with screening, but only about 50% to 60% of people who are eligible for screening actually take those tests,” said Grady, who is the medical director of Fred Hutch’s Gastrointestinal Cancer Prevention Program. “Getting people to be screened for cancer works best when we offer them screening options and then let them choose what works best for them.”
