A Clinical Trial That Could Lead to the Future of Cancer Screening

Megan Slocum, PA is a specialty care physician assistant at Inova Schar Cancer Institute.

The math is not complex.

Today, there are only five types of cancer that medical professionals routinely screen for: breast, cervical, prostate, lung and colon cancer. However, there are more than 100 types of cancer.

We know that cancer screening – and early detection of cancer – saves lives.

Developing new methods to reliably screen for additional cancers has the potential to significantly reduce cancer deaths. That’s why the Inova Saville Cancer Screening and Prevention Center is participating in a new clinical trial to test the effectiveness of liquid biopsy screening.

A liquid biopsy is a test run on a blood sample that looks for cancer DNA or cancer proteins that can be signals of an early-growing cancer in the body. The trial the Saville Center is joining is called Pathfinder 2. It’s the second phase of a trial that is evaluating the performance of the liquid biopsy test developed by California-based healthcare company GRAIL. Its Galleri test has the potential to identify more than 50 types of cancer.

Along with Saville Center Executive Director Rebecca Kaltman, MD, I will be enrolling patients and seeing them as Pathfinder 2 progresses. The trial, which will be run at multiple medical centers across the country, has a goal of enrolling approximately 20,000 patients in all. 

Specifically, Pathfinder 2 will be enrolling patients ages 50 and older who have not had a cancer diagnosis in the past three years.

I am excited to be a part of this effort. I believe – and many of my colleagues do as well – that this is the future of cancer screening.

Although Pathfinder 2’s primary goal is evaluating the performance of the Galleri test as an adjunct to routine cancer screening, the trial will also evaluate the psychosocial effects that this type of test has on individuals and their anxiety levels. Additionally, while anyone who is 50 or older and has not had a cancer diagnosis in the past three years can enroll, Pathfinder 2 is aiming to recruit an ethnically and racially diverse patient population. That should help ensure the results are broadly applicable to the general population.

A risk assessment, a blood test and a one-year follow-up

Patients interested in enrolling in Pathfinder 2 can enroll through the Saville Center. Once enrolled, they will receive the liquid biopsy and, shortly thereafter, their results. If a signal indicating the possibility of cancer is detected, we will investigate further via diagnostic tests, such as imaging, and, if needed, a biopsy.

The initial assessment also gives us a chance to see if a patient is eligible for additional screening based on their risk factors. That screening could include genetic testing or other, expanded cancer screening tests for high-risk individuals. If a cancer signal is not detected, patients will fill out a questionnaire after one year to see if a cancer not detected by the Galleri test has developed.

At its most basic level, the results from this clinical trial will help us understand how effective the Galleri test is at identifying early cancers. Based on what is known about the Galleri test from previous testing, it will not catch every cancer and is meant to be an adjunct to routine cancer screening. It is important that individuals participating in the Pathfinder 2 trial and other trials involving liquid biopsy tests understand that these tests, at least in their current state of development, will not eliminate the need for routine screening tests such as mammography, colonoscopy and pap smears.

Pathfinder 2 is part of an effort to expand and improve liquid biopsy testing. Galleri is one of several similar types of tests that are in development to provide the opportunity to detect cancers for which there is currently no optimal screening. Those cancers typically present at later stages when they are often incurable.

As a provider in the Saville Center participating in the Pathfinder 2 study, I know it will be incredibly rewarding to be able to identify a cancer in an individual that would otherwise have been undetected and likely caught at a much later and possibly less treatable stage.

The future: trials focused on high-risk patients?  

Pathfinder 2 is just one component of a growing research program at the Saville Center, which is aimed at using new technology to help with cancer early detection. In addition to other liquid biopsy trials, there are additional tools the Saville Center is studying such as nasal swabs and oral swabs that can predict one’s risk of developing lung and head and neck cancer, respectively. These new technologies are especially important because they are more easily deployed in rural and urban settings where access to healthcare is a concern.

In addition, we are focused on using these new tools in those whose cancer risk is higher than the general population, such as those with hereditary cancer syndromes (e.g., BRCA1 or BRCA2) or those with environmental exposures including firefighters or military personnel exposed to burn pits.

These initiatives are part of a larger mission at the Saville Center. We’re determined to use new technologies to perform more cancer screenings and to make those screenings more effective. As we do that, we will work to ensure that everyone has equal opportunity and access to our cancer screening and prevention services.

As I noted above, we’re participating in a trial that could lead us to the future of cancer screening. It is one of serval areas where we’re seeing encouraging developments in cancer prevention. I’m thrilled to be a part of it.


  1. Rogelio on February 2, 2023 at 9:35 am

    you did not include information on how to participate.

  2. Christine on February 2, 2023 at 10:39 am

    This is very promising. So glad to see some new techniques in cancer detection. It’s very much needed.

  3. Mary on March 13, 2023 at 11:20 am

    I would like to be contacted to be part of this study. I am out 7 years from my stage 4 pancreatic ca. I would love to see if this study can help me stay this way. I am also BRACA2 +,

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