Accurate blood-based clinical laboratory testing for cancer promises to encourage more people to undergo early screening for deadly diseases
One holy grail in diagnostics is to develop less-invasive specimen types when screening or testing for different cancers. This is the motivation behind the creation of a new assay for colorectal (colon) cancer that uses a blood sample and that could be offered by clinical laboratories. The data on this assay and its performance was featured in a recent issue of the New England Journal of Medicine(NEJM).
The company developing this new test recognized that more than 50,000 people will die in 2024 from colon cancer, according to the American Cancer Society. That’s primarily because people do not like colonoscopies even though the procedure can detect cancer in its early stages. Similarly, patients tend to find collecting their own fecal samples for colon cancer screening tests to be unpleasant.
But the clinical laboratory blood test for cancer screening developed by Guardant Health may make diagnosing the deadly disease less invasive and save lives. The test “detects 83% of people with colorectal cancer with specificity of 90%,” a company press release noted.
“Early detection could prevent more than 90% of colorectal cancer-related deaths, yet more than one third of the screening-eligible population is not up to date with screening despite multiple available tests. A blood-based test has the potential to improve screening adherence, detect colorectal cancer earlier, and reduce colorectal cancer-related mortality,” the study authors wrote in the NEJM.
As noted above, this is the latest example of test developers working to develop clinical laboratory tests that are less invasive for patients, while equaling or exceeding the sensitivity and specificity of existing diagnostic assays for certain health conditions.
“I do think having a blood draw versus undergoing an invasive test will reach more people, My hope is that with more tools we can reach more people,” Barbara H. Jung, MD (above), President of the American Gastroenterological Association, told NPR. Clinical laboratory blood tests for cancer may encourage people who do not like colonoscopies to get regular screening. (Photo copyright: American Gastroenterology Association.)
Developing the Shield Blood Test
Colorectal cancer is the “third most common cancer among men and women in the US,” according to the American Gastrological Association (AGA). And yet, millions of people do not get regular screening for the disease.
To prove their Shield blood test, Guardant Health, a precision oncology company based in Redwood City, Calif., enrolled more than 20,000 patients between the ages of 45-84 from across the US in a prospective, multi-site registrational study called ECLIPSE (Evaluation of ctDNA LUNAR Assay In an Average Patient Screening Episode).
“We assessed the performance characteristics of a cell-free DNA (cfDNA) blood-based test in a population eligible for colorectal cancer screening. The coprimary outcomes were sensitivity for colorectal cancer and specificity for advanced neoplasia (colorectal cancer or advanced precancerous lesions) relative to screening colonoscopy. The secondary outcome was sensitivity to detect advanced precancerous lesions,” the study authors wrote in the NEJM.
In March, Guardant completed clinical trials of its Shield blood test for detecting colorectal cancer (CRC) in men and women. According to the company press release, the test demonstrated:
- 83% sensitivity in detecting individuals with CRC.
- 88% sensitivity in detecting pathology-confirmed Stages I-III.
Additionally, the Shield test showed sensitivity by stage of:
- 65% for pathology-confirmed Stage I,
- 55% for clinical Stage I,
- 100% for Stage II, and
- 100% for Stage III.
“The results of the study are a promising step toward developing more convenient tools to detect colorectal cancer early while it is more easily treated,” said molecular biologist and gastroenterologist William M. Grady, MD, Medical Director, Gastrointestinal Cancer Prevention Program at Fred Hutchinson Cancer Center and corresponding author of the ECLIPSE study in the press release. “The test, which has an accuracy rate for colon cancer detection similar to stool tests used for early detection of cancer, could offer an alternative for patients who may otherwise decline current screening options.”
Are Colonoscopies Still Needed?
“More than three out of four Americans who die from colorectal cancer are not up to date with their recommended screening, highlighting the need for a more convenient and less invasive screening method that can overcome barriers associated with traditional options,” Daniel Chung, MD, gastroenterologist at Massachusetts General Hospital and Professor of Medicine at Harvard Medical School, said in the Guardant press release.
Barbara H. Jung, MD, President of the American Gastroenterological Association, says that even if Guardant’s Shield test makes it to the public the “dreaded colonoscopy” will still be needed because the procedure is used to locate and test polyps. “And when you find those you can also remove them, which in turn prevents the cancer from forming,” she told NPR.
There is hope that less invasive clinical laboratory testing will encourage more individuals to get screened for cancer earlier and regularly, and that the shift will result in a reduction in cancer rates.
“Colorectal cancer is highly treatable if caught in the early stages,” said Chris Evans, President of the Colon Cancer Coalition, in the Guardant press release.
Guardant Health’s ECLIPSE study is a prime example of the push clinical laboratory test developers are making to create user-friendly test options that make it easier for patients to follow through with regular screening for early detection of diseases. It echoes a larger effort in the medical community to think outside the box and come up with creative solutions to reach wider audiences in the name of prevention.
—Kristin Althea O’Connor
Related Information:
A Cell-free DNA Blood-Based Test for Colorectal Cancer Screening
A Simple Blood Test Can Detect Colorectal Cancer Early, Study Finds
Key Statistics for Colorectal Cancer