Cancer can be detected early enough to save lives. Doctors recommend regular screening for a variety of common cancer types.
mammograms and colonoscopies screen for different types of cancer.
Getting all these tests done can be difficult and expensive. A single blood test could be used to screen for most cancer types at once.
MCEDs are multi cancer early detection tests. The Cancer Moonshot is a federal effort to reduce the cancer death rate and improve the quality of life of cancer survivors.
I believe that MCED tests are likely to transform cancer screening in the near future if they receive strong federal support.
When a cell in the body dies, it leaves a trail of genetic material in the bloodstream. The traces of tumor DNA in the bloodstream are looked for by MCED tests. The circulating "cell-free" DNA has information about what kind of tissue it came from and whether it is normal or cancer-causing.
It's not new for testing to look for circulating tumor DNA. Patients with advanced-stage cancer are already using these liquid biopsies.
Doctors use the blood tests to look for tumors with certain genetic changes. It's relatively easy to detect genetic changes in patients with late-stage cancer because they tend to have a large amount of tumor DNA circulating in the blood.
When there aren't that many tumors yet, MCED tests are different from liquid biopsies. Cancer cells can be difficult to detect early on because noncancer cells can also shed their genetic material.
It's like finding a needle in a haystack if you detect the presence of cancer DNA in the bloodstream.
Making things more difficult is the fact that blood cells can be confused for cancer DNA. It was difficult to develop MCED tests with too many false positives.
New tests are able to avoid blood cell interference by using a type of "molecular barcode" embedded in the cancer DNA that identifies the tissue it came from. The barcodes are a result of naturally existing modifications to the surface of DNA that vary for different types of tissue.
The lung has a different pattern of genes. Cancer cells have abnormal genes that correlate with cancer types. MCED tests can focus on the sections of DNA that distinguish between cancer and normal tissue if they are cataloged.
Several MCED tests are currently being developed. The MCED test is not approved by the FDA.
The first commercially available MCED test was launched by GRAIL. The test says it can detect over 50 different types of cancer. Several US and Chinese companies have tests in development.
Different cancer detection methods are used in some of the tests, such as looking for cancer-linked genes in blood.
Insurance usually doesn't cover MCED tests. The company has a payment plan for people who have to pay out of pocket. MCED tests that get FDA approval are covered by a bill in Congress.
It is unusual for Congress to consider legislation for a single lab test, and this highlights both the scale of the medical market for MCED and concerns about access without coverage for these expensive tests.
It will take a long time to figure out how MCED tests should be used.
Questions on who should be tested, at what age, and how past medical and family history should be taken into account are just beginning to be addressed. Guidelines for how doctors will evaluate positive MCED results is equally important.
Concerns have been raised that MCED tests may result in overdiagnosing low-risk cancer. This happened with a screening for the disease.
Guidelines used to recommend that all men in their 50s and 60s get blood tests to determine their levels of PSA. The recommendation is more nuanced and takes into account personal preferences.
Further testing to confirm positive MCED results will be costly and a burden to the medical system. The out-of-pocket cost for an magnetic resonance image can be thousands of dollars.
Patients who get a positive MCED result but are unable to confirm the presence of cancer after extensive scans and other follow-up tests may develop lifelong anxiety about a potentially missed diagnosis.
Early studies show promise. 26 of 134 women with a positive MCED test were confirmed to have cancer, according to a 2020 study.
Half of the patients with a known cancer diagnosis had a positive MCED test, and only a small percentage had a false positive. About 17 percent of the patients who had very- early-stage disease were detected by the test.
The way clinicians approach cancer screening could be changed by MCED tests. Is the health care system prepared for them?
The School of Medicine at the University of Washington has a Professor.
Under a Creative Commons license, this article is re-posted. The original article is worth a read.
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