Detection CancerIt is possible to save your life by catching it early enough before it spreads throughout your body. Doctors do this because they know how to save lives. We recommend that you have regular screeningsA variety of techniques can be used to treat common types of cancer.
For example, colonoscopies can screen for cancer while mammograms look for breast cancer.
Although these tests are important, they can prove difficult, costly, and uncomfortable for patients. What if one blood test could be all it takes to screen for the most common types of cancer?
This is because of the promise of multicancer earlier detection tests (MCEDs). President Joe Biden made this a priority in his year by naming the development of MCED test tests as a priority. Moonshot for CancerA federal effort of US$1.8billion to reduce cancer deaths and improve quality of life for people living with and surviving cancer.
As a lab medicine Doctor and researcherI am a molecular test developer for cancer. I believe MCED tests will revolutionize cancer screening, especially if they are supported by the federal government.
How MCED exams work
All cells in the body, tumor cells included. Transmit your DNA to the bloodstreamWhen they die. MCED tests check for trace amounts of cancer DNA in the bloodstream. This “cell-free” DNA is a sample of DNA that has been circulated and contains information about the tissue from which it was taken. It also includes information about whether or not it is cancerous.
The blood test to detect circulating tumor DNA is not new. These liquid biopsies – a fancy way of saying blood tests – are already widely used for patients with advanced-stage cancer.
These blood tests help doctors identify any mutations in the tumor genome that can be used to guide treatment. It’s easy to spot genetic changes in patients with advanced cancer.
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MCED testing is different than existing liquid biopsies. They are able to detect early stage cancer when there aren’t many tumor cells. Because non-cancer cells also shed DNA, it can be difficult early on to identify these cancerous cells.
Because most of the DNA in bloodstream is from noncancer cells it’s easy to detect the presence of cancer DNA.
This makes things more complicated because blood cells naturally shed abnormal DNA with aging. These DNA strands can be confused with circulating cancer DNA. This phenomenon is called Clonal hematopoiesisMCED testing was not well-received in the beginning, and there were many false positives.
There are newer tests that can help. Blood cell interference is not to be allowedBy focusing on a type “molecular-barcode” embedded within the cancer DNA, which identifies the source tissue of the cancer. These barcodes are the result of DNA methylationThere are naturally occurring modifications to DNA’s surface that can be used for different types of tissues in the body.
Lung tissue, for example, has a different DNA-methylation pattern to breast tissue. A cancer cell’s abnormal DNA methylation pattern can correlate with its type. MCED tests are able to pinpoint the source of cancer by cataloguing the different DNA methylation pattern.
Test options
Currently, there are several MCED test in development. Clinical trials. No MCED testingCurrently FDA-approved.
GRAIL, a biotech firm, released the first commercially-available MCED test in America in 2021. It is Galleri testIt claims that it can detect more than 50 types of cancer. Two other US-based companies are also involved. Exact Sciences & Freenome, and one Chinese firm Singlera GenomicsTests are currently being developed.
These tests may use other cancer detection methods, including circulating tumor DNA and looking for cancer-associated protein in blood.
MCED tests aren’t covered by insurance. GRAIL’s Galleri Test is currently Prices starting at $949The company offers a payment option for those who can’t pay cash. Legislators Introduced a bill in CongressMedicare coverage will be provided for MCED testing that have been approved by the FDA.
It is rare for Congress to consider legislation devoted solely to a single laboratory test. This highlights the size of the medical market for MCED as well as concerns about access to these costly tests without coverage.
What should MCED testing be used for?
It will take years to figure out how MCED testing should be used in the clinic.
Clinicians and researchers are only beginning to answer questions about who should be tested and at what age. Setting guidelinesIt is equally important to know how doctors will further assess positive MCED results.
There is also concern about MCED testing causing overdiagnosis. Asymptomatic, low-risk cancers better left undetected. This is what happened to Screening for prostate cancer.
In the past, guidelines suggested that all men between 55 and 69 should have regular blood tests to assess their levels PSA. PSA is a protein made by non-cancerous and cancerous prostate tissue. However, the recommendations are more nuanced now that screening is recommended on an individual basis. This takes into consideration personal preferences.
There is also the concern that additional testing to confirm positive MCED results could prove costly and burdensome for the medical system, especially if a full-body scan needs to be done. An estimate of the out-of-pocket expense MRIFor example, you can Thousands of dollars.
Patients who receive a positive MCED but cannot confirm that they have cancer may experience lifelong anxiety and continue to undergo expensive scans in vain to find a tumor.
These concerns aside, early clinical trials show promise. There are many other benefits. 2020 StudyOut of more than 10,000 women who were previously not diagnosed, 26 of the 134 women who had a positive MCED tested were found to have cancer.
A GRAIL sponsored 2021 StudyThe MCED test was positive in half of the 2,800 patients who had a confirmed cancer diagnosis. Only 0.5 percent of those people with a negative test result had a false-positive test. This test was most effective for patients with advanced cancers, but it did not detect patients with very-early stage disease.
The MCED test could soon change the way that clinicians approach cancer screening. The question is whether the system of health care is ready for them.
Colin PritchardProfessor of Laboratory Medicine & Pathology, School of Medicine University of Washington
This article has been republished from The ConversationUnder a Creative Commons License Learn more Original article.
