Top doctors have warned against tests that claim to detect dozens of types of cancer, urging Americans that “we don’t have the evidence” and to stick to regular screenings.
Multiple cancer screening (MCD) has emerged as potential alternatives to invasive tests such as colonoscopies and mammograms. These tools, which primarily consist of blood draws, are intended to detect abnormal proteins and other cells consistent with cancer.
Like the full-body MRIs promoted by Kim Kardashian and Gwyneth Paltrow, many MCDs also claim to detect the disease before symptoms begin, meaning cancer is detected at earlier stages.
However, researchers presenting at the American Society of Clinical Oncology meeting in Chicago this weekend said that while the early studies are compelling, they would not recommend them to their patients and they are “not quite ready” to be widely prescribed.
They also warned that MCDs risk giving false positives, which could lead to patients undergoing a battery of unnecessary tests.
And these tools are not covered by insurance, and a single test costs more than $1,000.
The Guardant’s Shield blood test claims to detect colorectal cancers. While the FDA has deemed it safe, agency researchers said there is still more research to be done on MCDs.
The warnings come as health officials lower age guidelines for colorectal and breast cancer screening to combat a rise in the number of young people with the disease.
Dr. Chyke Doubeni, a family physician at Ohio State University, said in a presentation Friday: “We don’t have the evidence.” I believe these tests are not currently ready for prime time.’
“The risk of potential harm exists no matter how you look at it.”
Several recent reports on DCMs have shown promise, including two trials from the University of Oxford. In the first study, the team compared how proteins in blood samples from Britons diagnosed with cancer differed from those from those who did not have the disease.
They found 182 different proteins on average three years before cancer diagnosis.
In the second study, 40 proteins in the blood were found to influence a person’s risk of nine different types of cancer: bladder, breast, endometrium, head and neck, lung, ovarian, pancreas, kidney and malignant non-melanoma.
Additionally, research published earlier this year found that the Galleri test, which claims to detect 50 types of cancer and is being tested by the NHS in the UK, detected 18 types of early-stage cancers and claimed to be 93% accurate. percent.
However, at the time Paul Pharoah, a professor of cancer epidemiology at Cedars-Sinai Medical Center, said the “holy grail” for early detection was still far away, as more in-depth research was needed.
‘Many tests of this type have been developed or are being developed. “This paper reports initial results from the development of one of these tests,” he said. “Although the results are promising, it is too early to be confident that this test will be useful for early cancer detection.”
Dr. Robert A. Smith, an oncology researcher with the American Cancer Society, said in the presentation that a potential benefit of MCDs is that they could detect cancers at earlier stages.
“It would mean detecting the disease at an earlier stage in its natural history compared to symptoms, suggesting that the prognosis would be better,” he said.
However, he also noted that these “should not replace regular exams.”
The graph above shows the change in cancer case rates around the world.
MCDs also carry the risk of false positive results. “Although the false positive rate is low, the target audience is hundreds of millions of people,” Dr. Brewer said.
This could lead to patients having to undergo a battery of unnecessary, expensive and invasive tests, such as biopsies, to obtain a negative diagnosis.
said Dr. Ernest Hawk, vice president of Cancer Prevention and Population Sciences at MD Anderson Cancer Center in Texas, at a hospital. blog post: ‘Any positive blood test requires further diagnostic evaluation.’
‘Endoscopy, radiological imaging and biopsies require additional time, add costs and may pose additional risks due to the procedures themselves.
“We need to make sure that with this cancer prevention test we reduce incidents of cancer or improve cancer-specific survival,” Dr. Brewer said.
Dr. Brewer even suggested that the FDA and other agencies could begin to more strictly monitor tests and put limits on them before they hit shelves.
Earlier this month, the agency showed its support for the Guardant Health Shield test, which is designed to detect colorectal cancer, with a majority voting it safe.
However, Dr. Charity J. Morgan, a member of the FDA committee, said that while the test was “better than nothing for patients who receive nothing,” it is “no better than a colonoscopy.”
Dr. Jonathan M. Marron, a pediatric oncologist at Boston Children’s Hospital, said in the presentation that the research so far is going in a positive direction and, along with caution, optimism is key.
“MCDs may have value now and in the future, but their value remains to be clearly demonstrated.”
“There remains a great deal of uncertainty.”