Newsman: The Food and Drug Administration (FDA) on Monday approved Guardant Health’s blood test, called Shield, to screen for colon cancer. The test is generating enthusiasm among doctors who say it has the potential to boost the dismal rate of screenings for the cause of cancer. But it doesn’t mean to replace colonoscopies. Study says, colon cancer is the second-highest cause of cancer death in the United States.
The American Cancer Society estimates that more than 53,000 people will die of colorectal cancer this year.
Research published in March showed Shield was 83% effective in finding colorectal cancers. It works by detecting the DNA that cancerous tumors release into the bloodstream.
It’s most effective in finding later-stage cancers, when tumors release more of that DNA. The study found that Shield only detected 13% of earlier-stage polyps.
The test would need to be given at least every three years, starting at age 45 — the same age it’s recommended to begin colorectal screening.
A positive test isn’t necessarily a diagnosis. If the results indicate cancer is present, patients would still need a colonoscopy so doctors can see where tumors are and how far they’ve progressed.
Since the mid-1990s there’s been a troubling rise in colon cancer in people younger than 55, with rates increase increasing by 1% to 2% per year among that age group. At the same time, cases and deaths among adults 60 and older have been declining, according to the American Cancer Society.
Shield has previously been available to doctors as a screening tool, at an out-of-pocket cost of $895. With the FDA approval, Medicare and private insurance companies are much more likely to cover the cost of the blood test, making it more widely accessible for patients.
Colorectal cancer is one of the only cancers that can be prevented with screening, and colonoscopy is, by far, the most accurate way to detect it. But screening rates are extraordinarily low. Fewer than 60% of people who are eligible have had their recommended screening.
Another colon cancer screening method includes fecal occult blood tests that detect blood in the stool, which can be a warning sign of colon polyps or cancer. The FIT-DNA tests, such as Cologuard, are very effective at detecting cancer, but are less effective at detecting precancerous polyps.
This is the second blood test to screen for colon cancer; Epigenomics’ Epi proColon was approved in 2016. But it’s rarely used.
