A study published Wednesday showed positive results from a blood test for colon cancer and proposed a new type of screening method for the leading cause of cancer death.
This test looks for DNA fragments that have been shed by tumor cells or precancerous growths. It's already on sale in the U.S. for $895, but it hasn't been approved by the Food and Drug Administration and most insurance companies won't cover it. Guardant Health, the test's maker, expects an FDA decision later this year.
In this study, the test detected 83% of cancers, but colonoscopies found very few precancerous growths. Colorectal cancer screening. In addition to finding tumors, colonoscopies can also prevent disease by removing precancerous growths called polyps.
However, some people avoid exams because they don't want to take time off from work or because the preparations the day before require them to take strong laxatives to empty their bowels.
A convenient alternative is an annual stool test in which a stool sample is sent to a laboratory for analysis.
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“The best test is the one that someone actually completes,” said Dr. Douglas Corey, principal investigator at Kaiser Permanente in Northern California. He was not involved in this study. “Giving people a choice will increase the number of people getting tested.”
In the United States, screening tests are recommended for healthy adults ages 45 to 75 who are at average risk for colon cancer. Frequency varies depending on the test. Regular colonoscopies are performed on him every 10 years. Screening is progressing slowly, but it's still far short of the goal of screening 80% of eligible adults set by the American Cancer Society and other groups.
Guardant recommends a blood test called Shield every three years. As with stool tests, abnormal blood test results may require additional colonoscopies, which may increase your out-of-pocket costs.
This research was sponsored by Guardant. New England Medical Journal7,861 people in the United States underwent both a colonoscopy and a blood test.
Blood tests detected 83% of cancers found during colonoscopies, but missed 17%. This is equivalent to a stool-based test.
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There were also false alarms. For his 10% of people whose colonoscopies found nothing, blood tests incorrectly indicated they had possible colon cancer. That means a significant number of people face anxiety about follow-up colonoscopies.
Blood tests have been tailored to detect signs of colon cancer, but more research is needed to determine whether they can also detect other cancers and give misleading results, Corey said. said.
colorectal cancer Cancer is the second leading cause of death in the United States and the third leading cause of death worldwide. More than 153,000 new infections and 53,000 deaths are expected in the United States this year.
Dr. William Grady of the Fred Hutchinson Cancer Center in Seattle, a co-author of the study and a paid member of the Guardant Scientific Advisory Board, said more screening tests should reduce cancer deaths.
A separate study published Wednesday in the same journal found that an updated version of the Cologuard stool test that also detects DNA fragments appears to have better performance against false alarms, which could lead to fewer subsequent colonoscopies. . The study, which involved more than 20,000 participants, was sponsored by Exact Sciences, the company that developed the test.
“The more options patients have, the better,” said Dr. Nabil Mansour of Baylor College of Medicine, who was not involved in either study. He said he will continue to recommend colonoscopies to his patients, but is “excited to have some pretty good blood test options available.”
