How MCEDS Are Changing the Game in Cancer Detection

Promising advances in the fight against cancer are emerging with the development of minimally invasive early cancer detection tests, or MCEDs. Due to their non-invasive nature, MCEDs are seen as a relatively accessible option for cancer detection, allowing for earlier intervention and a better chance of recovery. These tests have spurred interest among cancer researchers, patients, and clinicians alike, but many challenges remain in their practical usage.

Overcoming challenges with cancer diagnostics

MCEDs are a recent advancement in cancer detection that work by analyzing blood samples for circulating tumor DNA (ctDNA), tiny fragments of DNA shed by cancer cells that can be detected in the bloodstream before any cancer symptoms appear. By detecting ctDNA, MCEDs can provide an early warning sign of cancer and enable patients to receive treatment before the disease has a chance to progress.

These tests are not meant to replace current screening tests but rather supplement them and help find cancers for which there are no proven testing methods. However, many unanswered questions remain about MCED tests’ accuracy, utility, and potential risks.

One important question is the accuracy of MCED tests in detecting cancer, especially for specific cancer types. Since MCED tests target multiple cancers, the accuracy for each cancer type might differ. Additionally, if MCED tests accurately find a specific cancer, they need to detect it early enough to improve treatment outcomes.

Another critical question is whether MCED tests can save lives and how much earlier they can identify cancer compared to when they would be detected after symptoms develop.

Experts tackling issues with MCEDs

Many of the critical issues associated with MCEDs were addressed by Phillip Febbo, Chief Medical Officer at Illumina, in a presentation at the recent American Association for Cancer Research (AACR) meeting held in Orlando, FL. There, he emphasized MCEDs’ potential to improve cancer outcomes globally.

In his talk “Improving cancer outcomes through equitable access to cfDNA tests,” Febbo stated that screening is one of the best ways to improve cancer outcomes and he highlighted the potential of MCEDs in early cancer detection. For example, he mentioned the success of using liquid biopsies to help children with Burkitt's Lymphoma in Sub-Saharan Africa. He also stressed the importance of accessibility and diversity in genomics analysis to better understand global populations and have more precise prevention screening.

Febbo noted that European ancestry comprises only 11% of the global population, yet takes up over 70% of ancestry backgrounds in published gene-associated studies. He stressed that we need more diversity in our genomics analysis data to understand worldwide demographics better and have more precise prevention screening.

One of the challenges in the fight against cancer is the low positive predictive value (PPV) of current cancer screening tests, meaning that many people go through diagnosis without actually having the disease. Febbo emphasized the need to tackle this challenge and encouraged researchers and scientists to pursue screening for additional forms of cancer as soon as possible.

Unlocking MCEDs’ full potential

There are numerous MCEDs being developed, but the Grail Galleri MCED test is highly anticipated as it can detect over 50 types of cancer through a simple blood draw. With this test, even cancers that are not generally screened for can be identified early on, potentially before symptoms arise. While this test has not yet been approved by the FDA, studies have shown that, when cancer signals were detected, the Galleri test localized those signals with high accuracy, helping inform the next steps to diagnosis (Liu et al., 2020).

Despite the potential of MCEDs, certain barriers to access for various groups of people have led to low adoption rates of cancer screening tests. An AACR cancer disparities report in 2022 found that adoption rates of various cancer screenings were relatively low. Additionally, even if everyone followed screening, there would still be a large portion of patients who may die due to cancers without available screening, including but not limited to pancreas, liver, bladder, brain, esophageal, kidney, ovarian, and more.

Febbo’s talk was just one of the presentations at the 2023 AACR conference that highlighted MCEDs’ potential to improve cancer outcomes with more precise risk assessment and screening approaches. Although MCEDs have advanced rapidly, in order to be successful clinical validity and utility must be established and patient acceptance evaluated. We look forward to more on those topics at next year’s meeting.

References

1. Liu MC, Oxnard GR, Klein EA, Swanton C, Seiden MV; CCGA Consortium. Sensitive and specific multi-cancer detection and localization using methylation signatures in cell-free DNA. Ann Oncol. 2020 Jun;31(6):745-759. doi: 10.1016/j.annonc.2020.02.011. Epub 2020 Mar 30. PMID: 33506766; PMCID: PMC8274402.