Is Galleri (multi-cancer early detection) testing recommended?

Galleri Testing is Not Currently Recommended for General Population Cancer Screening

The Galleri test (multi-cancer early detection test) is not currently recommended for routine clinical use or general population screening as it remains investigational and has not yet demonstrated reduction in cancer mortality.1

Understanding Cancer Screening Principles

The American Cancer Society (ACS) has established clear principles for recommending cancer screening tests:

• A screening test must be able to detect the majority of cancers at the time of testing
• The benefits must outweigh the risks, including false positives that may lead to unnecessary procedures
• Testing must be practical, feasible, and cost-effective for widespread implementation2

The ACS only recommends screening tests when scientific evidence has shown they will:

1. Reduce deaths and suffering from cancer
2. Help more people than they harm2

Current Status of Galleri Testing

The Galleri test represents an emerging approach to cancer screening that aims to detect multiple types of cancer through a blood test. However:

• It is still considered investigational and not yet recommended for routine clinical use1
• It has not yet demonstrated reduction in cancer mortality, which is the gold standard for screening test efficacy1
• Its clinical utility for population screening is still being evaluated in ongoing trials3, 4

Evidence on Multi-Cancer Early Detection Tests

Recent systematic reviews have found:

• Diagnostic accuracy of currently available multi-cancer early detection tests varies substantially
• For Galleri specifically, sensitivity ranges from 20.8-66.3% with specificity of 98.4-99.5%5
• Sensitivity is generally lower for detecting earlier-stage cancers (stages I-II) compared to later-stage cancers (stages III-IV)5
• There are no completed randomized controlled trials demonstrating mortality benefit5

Ongoing Research

The NHS-Galleri trial is currently underway, aiming to establish whether this MCED test can reduce late-stage cancer incidence in asymptomatic individuals. This large randomized controlled trial has enrolled over 140,000 participants from the general population in England.4 Results from this trial will help determine the clinical utility of population screening with the Galleri test.

Established Cancer Screening Methods

In contrast to emerging technologies like Galleri, traditional screening tests have:

• Undergone decades of validation and refinement
• Proven efficacy in reducing both cancer incidence and mortality for specific cancer types1

The ACS currently recommends established screening methods for specific cancers, including:

• Mammography for breast cancer
• Colonoscopy and other methods for colorectal cancer
• Pap tests for cervical cancer2

Potential Pitfalls of New Screening Tests

When evaluating new screening technologies, important considerations include:

• False positives leading to unnecessary procedures, anxiety, and potential harm2
• Overdiagnosis of indolent cancers that would never cause symptoms6
• Lead-time and length-time biases that can make screening appear beneficial even when it doesn't improve outcomes6

Conclusion

While multi-cancer early detection tests like Galleri show promise, they require further validation before being incorporated into general population cancer screening. Patients should continue to follow established screening guidelines and consult with their healthcare providers about appropriate cancer screening based on their individual risk factors.