Many of you are asking about the new blood tests that are available for colon cancer screening vs colonoscopy. After all, who wants to have a time consuming, messy procedure when you could just have your blood drawn?
Great question!
Colonoscopy examines the entire colon using a fiberoptic device to look for signs of colon cancer, and precancerous polyps, as well as other diseases. I am very happy that I have seen the number of colon cancers decline over my professional career due to this type of screening. My maternal grandfather died from colon cancer, and I am at high risk because of my own history of polyps. So, I am really happy to know that there is a way to prevent this terrible disease.
The reason that colonoscopy PREVENTS colon cancer from happening is that when the endoscopist ( the doctor preforming the procedure) examines the colon, they biopsy visible polyps REMOVING precancerous polyps so that they never turn into cancer. Colon polyps usually change into cancer slowly, which is why screening every 5 years if you are at high risk, and every 10 years if you are at low risk is usually enough.
Cologuard which is a stool test screen for the DNA fragments present in cancerous and precancerous polyps. If the test comes back positive, you still need to have a colonoscopy to evaluate further. It is not as accurate as colonoscopy, but does screen for precancerous polyps.
The blood tests that are available currently only screen for colon cancer, not for the precancerous polyps. That means that you could have a precancerous polyp in your colon and still have a normal test. That means your test is positive WHEN you have colon cancer, not before.
Right now, based on the information we have today, I recommend colonoscopy as a gold standard test for people who are able to safely have the procedure. You should always have colonoscopy if:
You, your mother, father, sister or brother have had colon cancer or precancerous polyps before
You smoke, you use marijuana, you have other toxic exposures ( like agent orange)
Cologuard is probable a reasonable options for people without these risks. It also might be a good choice for people who might have higher risk associated with anesthesia.
Right now, I am not recommending the blood tests for colon cancer screening because it does not tell us if you have precancerous polyps, and we miss the chance to PREVENT cancer. This may change as the technology changes.
Colon cancer screening should start at age 40 if you are at high risk, 45 if you are at low risk. If you have questions you can call the New Creation office at (603)642-6700.
