Researchers have developed a blood test that may revolutionize cancer testing. It can identify over 50 types of cancer, often long before symptoms develop.
Imagine being a woman concerned about a lump in your your breast, or a man worried about possible symptoms of prostate cancer. Or consider the plight of people who have no idea that what they and their doctors often assume is chronic indigestion is actually pancreatic cancer — a malignancy with a high fatality rate because it’s very hard to diagnose early.
These and countless other scenarios might play out in the not too distant future with less worry and better outcomes, thanks to a breakthrough in cancer screening.
The results of a study, published in Annals of Oncology, showed for the first time a blood test can accurately detect more than 50 types of cancer. What’s more, the test can also be used to pinpoint the tissue where the malignancy started, often long before there are obvious signs or symptoms of the disease.
Although advances in cancer treatment save many lives, cancer remains a top killer of Americans. In fact, the National Cancer Institute reports cancer is responsible for the death of over 600,000 people yearly in the U.S. Obviously, finding an easy way to screen for malignancies is key to better detection and early treatment (which can be less extensive and traumatic if a cancer is caught before It has spread).
“This is a landmark study and a first step toward the development of easy-to-perform screening tools,” said Fabrice André MD, PhD, director of research at the Gustave Roussy Cancer Institute in Villejuif, France, and editor-in-chief of Annals of Oncology. “Earlier detection of more than fifty percent of cancers could save millions of lives every year worldwide and could dramatically reduce morbidity induced by aggressive treatments. “
How a blood test can spot cancer using AI
The investigation into finding a blood test to diagnose cancer is part of the ongoing international Circulating Cell-free Genome Atlas (CCGA) study, involving 15,000 participants from 142 clinics in North America.
For this arm of the CCGA research, an international team (including scientists from Mayo Clinic, the Dana Farber Cancer Institute, Cleveland Clinic, and the University College London Cancer Institute) used high-tech DNA analyses to study the blood of over 4,000 study participants, about equal numbers with and without cancer.
They searched for specific markers related to changes in DNA. Tumors are known to shed DNA into the blood, contributing to what’s called cell-free DNA (cfDNA). But cfDNA doesn’t all come from cancer cells, so it can’t be used alone to pinpoint if cfDNA is the result of a malignancy.
That’s why the scientists zeroed in on analyzing chemical changes to DNA called "methylation," which mostly control gene expression. Abnormal methylation patterns that make changes in gene expression can contribute to the development of tumors. So, the research team looked for signals in cfDNA indicating abnormal methylation, to see if they could be used to detect cancer.
They used a blood test, targeting about one million of the 30 million methylation sites in the human genome, and artificial intelligence (AI) in the form of a machine-learning classifier (an algorithm) that analyzed and predicted the presence of cancer and the type of malignancy, based on the patterns of methylation in the cfDNA shed from tumors.
The AI classifier was “trained” using what’s believed to be the world’s largest methylation database of cancer and non-cancer signals in cfDNA (the database is owned by GRAIL, Inc., a company involved in funding the research).
Bottom line: Results so far are extremely accurate
The results of the test turned out to be remarkably accurate in detecting more than 50 types of cancer and identifying in which tissue the cancer originated. The false positives for cancer were only .7 percent — which means if the blood test was used on patients, less than one percent would be told, wrongly, they had cancer. Current methods of diagnosing cancer can result in far higher false positives. For example, about 10 percent of women who are screened with mammograms are incorrectly identified as having cancer, the researchers noted.
While more research is needed, the results so far indicate screening for cancer with a blood test could become a reality. It would likely be a game changer in the diagnosis and treatment of 12 types of cancer that are currently the most deadly because they are often found late — anal, bladder, bowel, esophageal, stomach, head and neck, liver and bile duct, lung, ovarian and pancreatic cancers, lymphoma, and cancers of white blood cells such as multiple myeloma.
"These data support the ability of this targeted methylation test to meet what we believe are the fundamental requirements for a multi-cancer early detection blood test that could be used for population-level screening: the ability to detect multiple deadly cancer types with a single test that has a very low false positive rate, and the ability to identify where in the body the cancer is located with high accuracy to help healthcare providers to direct next steps for diagnosis and care, “ said Michael Seiden, MD, PhD, president of the U.S. Oncology Network and senior author of the study.
"Considering the burden of cancer in our society, it is important that we continue to explore the possibility that this test might intercept cancers at an earlier stage and, by extension, potentially reduce deaths from cancers for which screening is either not available or has poor adherence. To our knowledge, this is the largest clinical genomics study, in participants with and without cancer, to develop and validate a blood test for early detection of multiple cancers."
April 17, 2020
Janet O'Dell, RN