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Are Multicancer Early Detection Tests Too Early for Primetime?

cancer screening galleri testing multicancer early detection tests Mar 27, 2024

With the recent diagnosis of cancer by Royalties- King Charles and Princess Catherine, it is evident that cancer is no respecter of persons. Early detection remains the best weapon in improving survival.

Among the promising developments in this area appears to be tests called multicancer early detection (MCED). These tests are designed to uncover various types of cancer early on, often before symptoms even manifest.

The question remains, however, "Are Multicancer Early Detection Tests too Early for Primetime?". Given my recent diagnosis of breast cancer, I have contemplated whether I wanted to add Mulitcancer Early Detection Testing as part of the offerings in my Direct Primary Care Practice.

This post delves into MCED tests, their benefits and potential drawbacks, and what the future might hold for the landscape of cancer detection and prevention.

What are Multicancer Early Detection (MCED) Tests?

We currently recommend screening for only five cancers: prostate, breast, colon, cervical, and lung. MCED tests utilize advanced technology to detect traces of cancer—such as DNA, RNA, and proteins—in the blood that might indicate the presence of cancer. Unlike traditional methods, which typically focus on a single type of cancer, MCED tests aim to identify multiple types simultaneously, offering a comprehensive screening approach.

The most popular MCED is the Galleri test. According to the website, Galleri checks more than 100,000 DNA regions and over a million specific DNA sites to screen for a signal shared by cancers that could be hiding. The Galleri test looks for cell-free DNA and identifies whether it comes from healthy or cancer cells. The DNA from cancer cells has specific methylation patterns that identify it as a cancer signal. Methylation patterns also contain information about the tissue type or organ associated with the cancer signal.

Current Clinical Trials Involving the Galleri Test

Although it is marketed as a tool for early cancer detection, it is unclear whether the Galleri test can be used for cancer screening. Clinical trials are looking into this, the largest of which is the NHS-Galleri test. This study has enrolled approximately 140,000 people in the United Kingdom aged 50 to 77 who had not been diagnosed or treated for cancer in the three years before enrollment. Unless diagnosed with cancer, participants in both arms will be returning for annual visits at approximately 12 and 24 months. All participants, whether test positive, test negative, or not tested, will be followed for cancer and associated outcomes via linkage to NHS routine datasets.

REFLECTION is a multi-center, prospective, non-interventional cohort study currently enrolling approximately 17,000 individuals who have opted to be screened with Galleri. The study aims to understand Galleri's real-world experience in clinical settings.

Patients prescribed the Galleri test as part of medical care by their healthcare provider will have the opportunity to consent to participate in this data collection study. Participants will be actively followed for 12 months from enrollment through data capture from electronic health records and periodic self-report questionnaires. Participants may be passively followed through linkages to cancer registries and other administrative health databases.

The PATHFINDER2  is also currently enrolling participants in North America.  This study aims to evaluate the safety and performance of GRAIL’s MCED test in individuals aged 50 years and older who are not actively being assessed or treated for cancer. Participants with a “cancer signal detected” test result will receive targeted diagnostic procedures based on the predicted cancer signal origin(s) to determine if cancer is present. The number and types of diagnostic procedures needed to achieve diagnostic resolution will be assessed. 


The Accuracy of the Galleri Test

According to a recent review in the Lancet, the overall sensitivity (true positive) for early-stage cancers (stage 1 and stage 2) is only 27.5%. The false positive rate is claimed to be 0.5%.


Drawbacks of the Galleri Test

At present, it is not clear that stage shifting- diagnosing a cancer at an earlier stage- actually translates into a lower mortality rate.

The Galleri test is not covered by insurance in the United States. The cost to consumers on the company's website is $949.00.

At present, the Galleri test is not FDA-approved in the United States. It was given the FDA's Breakthrough Devices Program in 2019. The Breakthrough Devices Program is a voluntary program for certain medical devices and device-led combination products that provide more effective treatment or diagnosis of life-threatening or irreversibly debilitating diseases or conditions.


Looking Ahead: The Future of Cancer Detection and Prevention

The journey towards perfecting MCED tests is ongoing, with research and trials to enhance their accuracy and reliability. These tests' potential to revolutionize cancer detection and treatment is immense, promising a future where cancer can be caught and treated earlier. But in my evaluation, they are not ready for primetime.





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