Unveiling the Future of Cancer Detection: The Promise of Multi-Cancer Tests (MCTs)

Jul 24, 2024

Cancer, a leading cause of death worldwide, can often be treated more successfully when detected early. The earlier the diagnosis, the more treatment options are available, ultimately improving survival rates and quality of life for patients. Recent advances in medical technology, particularly in the realm of liquid biopsy, are revolutionizing the landscape of early cancer detection and diagnosis. These developments offer a paradigm shift in how we approach cancer screening, particularly through the advent of multi-cancer tests (MCTs).

 What Are Multi-Cancer Tests?

Multi-cancer tests (MCTs) are innovative tools designed to detect multiple types of cancer from a single sample, such as blood, urine, saliva, or stool. By analyzing these samples, MCTs look for markers indicative of cancer, such as fragments of cancer DNA, proteins, or other metabolites released by cancer cells. These tests employ sophisticated algorithms to interpret the data, estimating the risk of cancer presence and often pinpointing the probable location of the cancer within the body.

Examples of MCTs include the Galleri, Shield, and Delfi tests, which primarily focus on detecting cancer DNA in the blood. The versatility of these tests is what makes them so promising; they have the potential to screen for various cancers simultaneously, unlike traditional methods that target a single type of cancer.

Multi-Cancer Early Detection Tests (MCEDs): A Specialized Use

Among the potential applications of MCTs, using them for population-wide cancer screening is particularly exciting. For clarity, when we refer to MCTs used in this context, we call them multi-cancer early detection tests (MCEDs). The idea is to screen asymptomatic individuals—those who appear healthy—to catch cancers at their earliest, most treatable stages.

Current cancer screening programs typically focus on individual cancers. For instance, mammograms are used to detect breast cancer, and FIT tests are used for bowel cancer detection. While these programs have significantly reduced cancer mortality, they are limited in scope. MCEDs, however, could transform cancer screening by enabling the detection of multiple cancers, including rarer types that lack dedicated screening programs.

 Challenges and Considerations in Implementing MCEDs

Introducing MCEDs into population screening involves navigating several complex factors. Key among these is the need for high diagnostic accuracy. An ideal MCED must minimize false positives (incorrectly identifying healthy individuals as having cancer) and false negatives (failing to detect cancer in affected individuals). Moreover, it is crucial to avoid overdiagnosis—detecting cancers that would not cause harm if left untreated.

Screening trials play a vital role in assessing these factors. They are extensive and time-consuming, as they aim to balance the benefits of early detection against the potential harms of misdiagnosis and overdiagnosis. While promising, MCEDs still require robust evidence to demonstrate their efficacy and safety before they can be adopted on a large scale.

 The Path Forward

The global research community is actively exploring and refining various MCEDs. Despite the progress, it will be several years before these tests might be integrated into national screening programs. During this period, it is essential to establish rigorous evaluation frameworks to determine the most suitable tests and their appropriate use cases.