The Galleri test can detect more than 50 kinds of cancer
By the end of 2022, according to the American Cancer Society, there will be an estimated 609,360 deaths caused by cancer in the United States. As the second leading cause of death in the U.S., it’s important that we catch, diagnose and treat cancer as early as possible. While there are standard screening tests for a handful of common cancers, most cancers, including rare cancers, don’t have any tests that allow for early detection. Now, thanks to the Galleri test, there’s a game-changing technique to catch more than 50 kinds of cancer in one simple blood test.
“Currently, we don’t detect the majority of cancers, including highly lethal ones, such as pancreatic or ovarian cancer, until symptoms are present,” says Dr. Klein. “But Galleri can find those cancers at a time when they’re in an earlier stage and before symptoms appear.”
Many cancers shed DNA into your bloodstream, known as cell-free DNA or circulating tumor DNA. This DNA is usually shed as cancer cells die. Using what’s called Next-Generation DNA Sequencing and machine learning, doctors are able to use a single blood draw (test) to look at various patterns in that DNA code and figure out two things: if a cancer signal is present, and from where the cancer likely started.
These patterns in your DNA are possible because of a biological process known as methylation. During this process, your body expresses certain genes but not others. You can picture it like a wall of light switches: for every switch you turn on, others might turn off, and different configurations produce different results. So, a skin cell will have one configuration, while a liver cell will have another. In the same way, healthy cells will have one configuration, while cancer cells will have a different one. And specific cancer types will have specific configurations different from other cancer types. If a cancer signal is detected, the Galleri test is able to identify which organ system the cancer is likely coming from with about 90% accuracy. If this happens, you would then have another test (like a blood test, CT scan or ultrasound of your kidneys, lungs, pancreas or other affected system) to verify the presence of cancer.
“Twelve cancers, including anal, bladder, colorectal, esophageal, head and neck, liver/bile-duct, lung, lymphoma, ovary, pancreatic, plasma-cell neoplasm and stomach cancer, account for about two-thirds of all cancer deaths in the U.S.,” says Dr. Klein. “For these 12, Galleri finds about 40% of stage I cancers, 67% of stage II cancers, 80% of stage III cancers and 95% of stage IV cancers.”
How accurate is the Galleri blood test?
Depending on the test, traditional screening tests have a false-positive rate of 10% to 40%. Galleri has a 0.5% false-positive rate, which means it’s highly accurate.
“It finds 51.5% of cancers,” points out Dr. Klein. “If you look at the 12 cancers that account for two-thirds of all deaths in the U.S., it actually finds 67% of those.”
And it’s 89% effective in predicting where the cancer started.
This is huge for cancer types such as #ovarian that are often either caught too late or misdiagnosed. There are currently no early detection tests for ovarian cancer unless you request a transvaginal ultrasound (which is not always easy due to insurance) and a CA-125 test. Also, ovarian cancer is usually misdiagnosed as GERD because many of the symptoms initially are GI related and patients are usually given antacids, self treat and/or women ignore them.
The CA-125 test is very limited and usually only given if a patient is showing symptoms and already in a later stage of the disease. The levels are also directional. For example, when my mom had ovarian cancer her levels fluctuated all over the place. While you wait and hope that they drop when you start treatment or after a debulking surgery a low CA-125 number does not automatically mean your treatment is working. You can have a low number and still be very staged out.
Because high CA-125 levels can be a sign of other conditions besides ovarian cancer, this test is not used to screen women at low risk for the disease. A CA-125 blood test is most often done on women already diagnosed with ovarian cancer. It can help find out if cancer treatment is working, or if your cancer has come back after you have finished treatment.
Currently, the Galleri test isn’t U.S. Food and Drug Administration (FDA) approved. For now, if you’re over the age of 50 and have a family history of cancer, are at higher risk for cancer or you’re immunocompromised and you’re interested in taking the Galleri test, you should talk to your healthcare provider. They can register with GRAIL and order the test (the healthcare company responsible for developing the Galleri test).