The Shield blood test accurately detects colorectal cancer around 83% of the time and can spot precancerous lesions about 13% of the time. Despite being available for $895, it hasn’t received FDA approval yet.
Main Points:
The Shield blood test accurately identifies colorectal cancer approximately 83% of the time and can detect precancerous lesions around 13% of the time. Although available for $895, the test is not yet FDA-approved.
– The Shield blood test accurately detects colorectal cancer around 83% of the time.
– It can identify precancerous lesions about 13% of the time.
– The test is currently available for $895 but lacks FDA approval.
A recent study published in the New England Journal of Medicine on March 14 highlights a new blood test that demonstrates a remarkable accuracy in detecting colorectal cancer. The Shield blood test can identify 5 out of 6 cases of colorectal cancer, offering a promising advancement in cancer screening. This test, which requires less preparation and fewer steps compared to current methods, is anticipated to undergo review by the U.S. Food and Drug Administration (FDA) in the coming week.
According to William M. Grady, MD, a gastroenterologist at Fred Hutch Cancer Center in Seattle and the corresponding author of the study, the accuracy rate of this blood test is comparable to that of at-home stool tests commonly used for early detection of colorectal cancer. Dr. Grady suggests that the simplicity and efficiency of the blood-based test could make it a preferable option for patients who are reluctant to undergo current screening methods.
Sean Langenfeld, MD, a colorectal surgeon at Nebraska Medicine in Omaha, who was not part of the study, expresses optimism about the addition of this new screening option. He acknowledges the importance of providing patients with a variety of screening methods, potentially increasing participation and early detection rates, which ultimately improves outcomes for those at risk of colorectal cancer.
“Colorectal cancer is common, deadly, and preventable. It’s the third most common cancer and the second leading cause of cancer-related death,” he said. Despite this, only around 60 percent of the public actually get the proper screening that they need, Dr. Langenfeld said.
Early Detection Could Save Your Life
Over the last few decades, there has been a consistent decline in the incidence of colorectal cancer, though this decline hasn’t extended to younger adults. In fact, the number of individuals under 55 being diagnosed with colorectal cancer has almost doubled in the last 30 years.
When colorectal cancer is detected early, before it metastasizes, the five-year relative survival rate stands at 91 percent. However, if the cancer has already spread to distant parts of the body, the survival rate plummets to just 13 percent. This underlines the critical importance of early detection and intervention in improving survival outcomes for colorectal cancer patients.
“Having a blood-based screening test available will lead to more patients agreeing to undergo screening and hopefully improve screening rates, as they see it as less invasive,” Langenfeld said.
Blood Test Accuracy Measured and Compared with ‘Gold Standard’ Colonoscopy
To assess the efficacy of a blood test as a potential alternative to colonoscopy, the established gold standard for colorectal cancer screening, a research endeavor recruited close to 8,000 individuals aged between 45 and 84 years. With an average age of 60, and a gender distribution of 54 percent women, the cohort was demographically representative, mirroring the racial and ethnic composition of the 2020 U.S. Census data. The majority, 78.5 percent, identified as white, followed by 12 percent Black and 7 percent Asian, with approximately 13 percent identifying as Hispanic or Latino.
The study’s criteria mandated that participants belonged to the “average risk” category for colorectal cancer, meaning they lacked a family history of the disease, personal cancer history, and inflammatory bowel disease or significant polyps. Among those screened, 7,861 individuals met these criteria, undergoing both a colonoscopy and the blood test.
Of the 65 cases of colorectal cancer detected through colonoscopy, the blood test correctly identified 54, yielding a sensitivity rate of 83 percent. However, the blood test exhibited greater efficacy in detecting colorectal cancers, even at early stages, yet demonstrated reduced accuracy in identifying advanced precancerous lesions, which harbor the potential to progress to cancer over time.
The Shield Test Vs. Current Available Methods
A colonoscopy stands as the gold standard for detecting polyps and colorectal cancer, offering a high level of reliability. However, it involves several preparatory steps. Firstly, you need to adhere to a specialized diet, then cleanse your bowels using laxatives. Following this, the procedure itself requires sedation, anesthesia, or pain medication, and necessitates arranging transportation for the journey home.
If the colonoscopy reveals nothing unusual, it’s recommended only once every ten years. This procedure is not only crucial for early detection but also potentially life-saving, as it can identify and remove precancerous polyps before they develop into cancer.
In addition to the Shield blood test, there are two main at-home tests for colorectal cancer:
- The FIT (fecal immunochemical test) is approximately 79% accurate in detecting colon cancer. This test comes as a kit, with instructions and materials for safely collecting a small amount of fecal matter to be sent to the lab for analysis. It’s recommended to repeat the test every 1 to 2 years.
- Cologuard (fecal DNA testing) has a 92% accuracy rate. Like the FIT, it involves collecting a sample and mailing it off, but this test should be repeated every 3 years.
Langenfeld states that the accuracy of the Shield blood test in detecting colorectal cancer is quite comparable to current stool-based tests, such as FIT, but slightly lower in sensitivity compared to fecal DNA testing like Cologuard. He adds that it boasts a specificity of 90 percent, indicating few false alarms are triggered by this test.
It’s advised that the Shield test be repeated every 3 years. If a person receives a positive result, it’s recommended they undergo a colonoscopy to confirm whether the result is a true positive or a false positive.
Blood-Based Screening Technology Researched for Breast and Lung Cancer
The Shield test identifies signals of colorectal cancer in the blood, which come from DNA shed by tumors, known as circulating tumor DNA (ctDNA). Grady states that this technology shows great promise and is currently under study for screening other types of cancer such as breast and lung cancer.
Users for Colorectal Cancer Test
“This test is most appropriate for patients unable or unwilling to undergo colonoscopy — that’s who I would recommend it to. Since it is fast, easy, and noninvasive, it will seem like less of a commitment, and will hopefully lead to people undergoing screening who would have otherwise continued to put it off for the foreseeable future,” Langenfeld said.
That being said, the test still wasn’t as effective in spotting precancerous lesions. In fact, it was only able to identify 13 percent of the time. “I will still recommend screening colonoscopy for most patients,” he added.
Polyps are frequently found in older adults, and the majority of them are noncancerous, or benign. However, over time, some polyps may develop into cancer. Langenfeld highlights that one advantage of a colonoscopy is the ability to remove precancerous polyps during the procedure.
Grady suggests discussing with your healthcare provider to determine the best option for you. Currently, nearly half of individuals offered a choice between a stool-based test or a colonoscopy for colorectal cancer screening opt for neither, he noted.
Shield Seeking Both FDA Approval and Medicare Coverage
The Shield test, introduced in May 2022, requires a doctor’s prescription for access. Since its launch, it has been utilized by over 20,000 individuals. According to a recent press release, the company stated that these results potentially pave the way for the first FDA-approved blood test for colorectal cancer screening to meet Medicare coverage requirements.
Guardant Health, the manufacturer of the Shield test, submitted the final paperwork for premarket approval in March of the previous year, and the FDA is expected to make a decision soon.
Until FDA approval, most individuals will likely have to pay out-of-pocket for the Shield test, which is priced at $895, as reported by USA Today.
When to Get Screened for Colorectal Cancer
Both the American Cancer Society and the U.S. Preventive Services Task Force advise individuals with average risk to begin colorectal cancer screening at age 45. If you have health insurance, you might not have to cover any deductible or copay for these screenings. For further details, explore the Centers for Disease Control and Prevention’s webpage dedicated to colorectal cancer screening.
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