Cancer Screening

Doctors consider a colonoscopy the “gold standard” or the best test for colorectal cancer prevention. However, most people try to avoid this procedure because of embarrassment, cost, discomfort, and the prep required to clean out the colon. Fortunately, anesthesia has made this process tolerable, and the Affordable Care Act (ACA), also commonly known as Obamacare,  requires insurance companies to pay for the procedure, which may cost between $2,000 - $5,000 otherwise.  Scientists have developed two other methods to help detect early colorectal cancer. These are  stool and blood tests. These are both easier to do, take less time, and have less risk of complications. The stool tests look for traces of blood and tumor DNA. The blood tests look for traces of tumor DNA and RNA. The stool tests are the least expensive option, up to $700,  and are usually covered under the ACA while the blood tests cost around $1,500 and are not always covered by insurance. While cost is important, the most important question is Are they as good as a colonoscopy?

To evaluate the effectiveness of these options, an article just published in the Annals of Internal Medicine by Dr. Uri Ladabaumⁱ compared a colonoscopy every 10 years, a stool test every year, or a blood test every 3 years vs no screening. Of those 3 main options to look for colorectal cancer, regular colonoscopies proved to be the most effective method in reducing the risk of getting colorectal cancers. This is because colonoscopies also detect and remove colon polyps before they turn into cancers.  More importantly, the risk of dying from colorectal cancer was reduced 81% with colonoscopies, about 74% with the stool tests, and 55% with the blood tests, when compared to not screening. Thus, whichever method you choose, they are all effective, with a colonoscopy still the best test.

While all 3 methods can detect cancer, only colonoscopies are recommended for people at high risk, such as Lynch syndrome. The main reason is effectiveness. As shown above, colonoscopies significantly reduce the death rate from colon cancer compared to the stool or blood tests. The second reason is the ability to remove precancerous lesions. And lastly, colorectal cancer with Lynch syndrome grows faster so it is important to identify and remove abnormalities as soon as possible.

Uri Ladabaum, Ajitha Mannalithara, Robert E. Schoen, et al. Projected Impact and Cost-Effectiveness of Novel Molecular Blood-Based or Stool-Based Screening Tests for Colorectal Cancer. Ann Intern Med. [Epub 29 October 2024]. doi:10.7326/ANNALS-24-00910