Imagine going to your doctor and getting a simple blood test that could tell you if you have cancer—even before you have symptoms. The test has the potential to catch cancer at the earliest stages when it is usually more treatable.
That is the idea behind multi-cancer detection tests, or MCD tests. These tests are still new. There are still more questions than answers.
You may have read about MCD tests in the news. LTFU Update wants to make sure you have the information you need to understand and make choices.
We spoke with Ruth Etzioni, PhD, a researcher at Fred Hutchinson Cancer Center, to help explain what these tests are, what they can and cannot do, and what childhood cancer survivors should keep in mind. Etzioni is a scientist who studies early screening and diagnostic tests.
What Is an MCD test?
MCD tests are blood tests that look for potential signs of cancer in your body, Etzioni says. The goal is to find cancer early—before it spreads or causes symptoms. The 2 main MCD tests available are Galleri® and Cancerguard™. Dozens of other companies are also developing tests.
At the time of this writing, MCD tests are not approved by the FDA to diagnose cancer.
MCD tests are expensive. Most insurance plans do not cover them. Galleri® costs $949. Cancerguard™ costs $689. That does not include the needed blood draws.
Do MCD tests work?
Etzioni says the science behind MCD tests make sense, but we do not yet know how useful they really are.
“We have not proved the worth of these tests,” she explains. “That is why researchers are doing large studies to find out if MCD tests actually help people live longer or avoid serious illness.”
The National Cancer Institute’s Cancer Screening Research Network has launched the Vanguard Study, a study of MCD tests. This study looks at whether the test works in the real world, in a variety of groups of people and locations.
What MCD test results mean
If an MCD test comes back positive for cancer, you might have cancer. You will need more tests to find out for sure. Your health care provider could recommend more tests such as a PET scan, CT scan, or an MRI.
But here is the catch: These tests can cost hundreds or thousands of dollars. Your insurance might not cover them. And even if you have further tests, it may be too early for them to find evidence of cancer.
Or test results could cause health care teams to take an overly aggressive approach to cancer. This lesson was learned from prostate cancer. Many men had their prostates removed when it would have been better for health care providers to watch them closely. Many prostate cancers grow so slowly that they would not have caused problems.
If an MCD test comes back “negative” for cancer, that does not mean you are cancer free. It means that the test results are not at the level needed to have a positive result for cancer. The currently available tests are designed to prevent “false positives,” or showing a positive result when you do not have cancer. So, your evidence of cancer would have to be at high level for the test to come back as positive for cancer.
Etzioni says it is important to ask questions before moving forward:
- How accurate is the follow-up test?
- Will my insurance cover it?
- What are the risks of doing more tests?
- What happens if the follow-up test does not find anything?
“You don’t want to end up with a big medical bill or go through stressful procedures unless you really need to,” Etzioni says. “Having tests and waiting on results causes anxiety.
And there is no guarantee you could do anything with the information right now. Plus, advanced imaging tests like MRIs and CT scans sometimes identify things that seem suspicious but turn out to be harmless.”
What else should childhood cancer survivors consider?
If you had cancer as a child, you want to catch problems early. But Etzioni says it is important to stay realistic.
Here are things to keep in mind:
- Talk to your doctor first. Do not buy a test online or go to a clinic without medical advice.
- Avoid company websites for information. They are trying to sell you something. They may make the test sound better than it really is.
- Look for trusted sources. The American Cancer Society has helpful information, and your survivorship care team can guide you.
- Be careful of copycat tests. Some tests say they are MCD but are not based on the latest science.
Putting it all in perspective
MCD tests are a promising idea, but they are still under study. They might help in the future. But right now, they are not a guaranteed way to find cancer early.
Etzioni says we need more information before we can know these tests are likely to be useful for large-scale screening. “I think this approach has potential for cancer survivors who we know have higher cancer risk than other groups,” Etzioni says. “But it is still early days.”
If you are interested in MCD tests, take your time. Ask questions. Talk to your health care provider. And remember—your health is about more than 1 test. Staying informed, keeping up with regular checkups, and knowing your body are all important parts of taking care of yourself.