Cancer is the second-leading cause of death in the U.S., behind heart disease. This is in part because research shows that roughly 50 percent of cancers are diagnosed once they've already reached an advanced stage. However, according to the Centers for Disease Control and Prevention (CDC), "Approximately 30% to 50% of cancers diagnosed today could be prevented by reducing exposure to tobacco smoke and other environmental carcinogens, maintaining healthy body weight, and receiving recommended cancer screenings and vaccinations."
Now, researchers have found that a simple blood test could detect some cancers up to three years before a diagnosis, a groundbreaking discovery that has the potential to drastically improve survival rates.
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Doctors detect tumors in the bloodstream three years before diagnosis.
In a new study published in the journal Cancer Discovery, researchers detected genetic material shed by tumors in the bloodstream three years before a cancer diagnosis.
"Three years earlier provides time for intervention," said lead study author Yuxuan Wang, MD, PhD, an assistant professor of oncology at the Johns Hopkins University School of Medicine, in a press release. "The tumors are likely to be much less advanced and more likely to be curable."
To arrive at these findings, the researchers used "highly accurate and sensitive sequencing techniques" to analyze the blood samples of 52 participants, half of whom were diagnosed with cancer within six months of the blood draw and half of whom were not.
Sequencing, also referred to as genomic sequencing or DNA sequencing, is an umbrella term for the scientific process of extracting the "biological information that cells use to develop and operate," as the National Human Genome Research Institute explains. This can detect cellular changes that can indicate disease such as cancer.
At the time of the blood sample collection, sequencing showed that eight study participants scored positively on a multicancer early detection (MCED) laboratory test. Four months later, all eight were diagnosed with cancer. Moreover, six of these participants showed "tumor-derived mutations" in blood samples that were collected roughly three years before diagnosis. Four showed mutations even earlier.
"These results demonstrate that it is possible to detect circulating tumor DNA more than three years prior to clinical diagnosis, and provide benchmark sensitivities required for this purpose," states the study.
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Will MCED tests become widely available?
"Detecting cancers years before their clinical diagnosis could help provide management with a more favorable outcome," stated senior study author Nickolas Papadopoulos, PhD, professor of oncology at the Ludwig Center. "Of course, we need to determine the appropriate clinical follow-up after a positive test for such cancers."
To his point, the American Cancer Society notes that MCED tests are still being studied and have not yet received approval from the U.S. Food & Drug Administration (FDA) for use in patients.
Generally speaking, MCED tests "check blood samples for signs of cancer, such as pieces of DNA, RNA, or proteins from abnormal (cancer) cells," explains the Society. "Some MCED tests may suggest where in the body the cancer started. Others may only show that cancer could be present, without identifying the type or location."
However, it's important to understand that MCED tests do not diagnose cancer. If a test is positive, a patient would need additional testing to "confirm whether cancer is present, what type it is, and where it’s located," they add.
Currently, a blood-based MCED test called the GRAIL Galleri test is available via the Clinical Laboratory Improvement Act (CLIA), which allows doctors to order the test since it's done in a central lab. According to the test's official website, it can detect more than 50 types of cancer, including colon and rectal cancers, Leukemia, prostate cancer, and breast cancer.
But the American Cancer Society notes that the GRAIL Galleri test is often not covered by insurance and may provide false negative or positive results.
As for the current study and others like it, research is ongoing.
