NBC News
The Food and Drug Administration on Monday approved Guardant Health’s Shield blood test for colon cancer. The test is not intended to replace colonoscopies, but it is generating excitement among doctors who believe it has the potential to improve the dismal rate of screening for the second-leading cause of cancer deaths in the United States.
Shield was already available as a screening method but at a cost of $895. Now, with FDA approval, it is much more likely that Medicare and private insurance companies will cover its cost, which would make it more accessible to patients.
Dr. Arvind Dasari, a professor of gastrointestinal and medical oncology at the University of Texas MD Anderson Cancer Center, called the approval a “welcome step forward” but cautioned: “We’ll have to wait and see what the impact will be in terms of improving the study and reducing mortality.”
The American Cancer Society estimates that more than 53,000 people die from colorectal cancer each year.
Research published in March showed Shield was 83% effective at detecting colorectal cancers by identifying DNA released into the bloodstream by tumors.
This makes it more effective at detecting cancers in advanced stages, when they release more DNA. According to this study, Shield only detected 13% of polyps in early stages.
The test must be done at least every three years, starting at age 45, the same age at which colorectal analysis is recommended.
A positive result does not necessarily mean a diagnosis of cancer. If the results indicate the presence of a tumor, a colonoscopy is still necessary so that doctors can see where it is and how far it has progressed.
“People need to understand that a positive test requires a colonoscopy to confirm that there is an advanced lesion or colorectal cancer, or that the results were false,” said Robert Smith, vice president of Cancer Early Detection Science at the American Cancer Society. “A test like that is not complete if it’s positive and you haven’t had a colonoscopy,” he said.
This is the second blood test to detect colon cancer; Epigenomics’ Epi proColon was approved in 2016, but it is rarely used, according to Smith, because of concerns about its accuracy. It is also not covered by Medicare or private insurance.
Since the mid-1990s, there has been a worrying rise in colon cancer in people under age 55, with rates increasing by 1% to 2% annually in that age group. Cases and deaths among adults age 60 and older have been declining, according to the American Cancer Society.
“What breaks my heart is that it is preventable,” said Dr. William Grady, a gastroenterologist at Fred Hutchinson Cancer Center in Seattle. “One of my greatest joys is when I do a colonoscopy and I can remove polyps” that, if undetected, would have turned into cancer, he added.
Colorectal cancer is one of the only cancers that can be prevented by screening, and colonoscopy is by far the most accurate way to detect it. But rates of these screenings are extraordinarily low. Less than 60% of eligible people have undergone the recommended screening.
“The biggest problem with colon cancer today is that a significant portion of the population is not being screened,” said Dr. Sapna Syngal, director of strategic planning for prevention and early detection at Dana-Farber Cancer Center in Boston. “If this test increases the number of people who are screened, it’s going to have a huge impact,” she said.
Grady, who led the March study of the Shield test, said it is often adults in their 40s and 50s who are least likely to comply with screening.
“These are working people, many of whom have families, so they have other life responsibilities that prevent them from taking care of themselves,” he added.
Colonoscopy is time-consuming and requires at least a day off work. Many people find the procedure unpleasant, in which a camera is inserted into the rectum to look for tumors or spots that might become cancerous. The camera needs a clear view of the colon, so patients have to take a strong dose of laxatives the day before.
“A lot of people don’t like the mess of dealing with stool and they really don’t like colonoscopy, especially the prep,” said Electra Paskett, deputy director of population sciences and community outreach at Ohio State University’s Comprehensive Cancer Center. “I think a blood test would be ideal for a lot of people,” she added.
Another method for detecting colon cancer is fecal occult blood testing, which can be a warning sign of colon polyps or cancer. FIT-DNA tests, such as Cologuard, are very effective at detecting cancer, but not as effective for precancerous polyps.
John Gormly, 77, of Newport Beach, California, had avoided a colonoscopy for years. When his doctor offered him the option of the Shield blood test, he took it.
“He called me the next day and said, ‘I don’t like the results at all. I’m going to send you for a colonoscopy,’” Gormly recalled. “It turned out I had stage 2 colon cancer.”
Surgeons were able to remove the entire tumor. “Thank God I had that blood test,” Gormly said, “I never felt anything, I never knew anything was wrong. Without that blood test, I don’t know how I would have ended up.”