In a trial, an innovative Galleri blood test found multiple cancers, most of which have no routine screening available.
Healthcare company GRAIL announced the final results from the PATHFINDER study, which evaluated multi-cancer early detection (MCED) screening using the Galleri test, which looks for cancer DNA in blood, and the clinical care pathways.
The study involved 6,662 individuals aged 50 years or older, an age group at elevated risk for cancer. Using the Galleri blood test, a cancer signal was found in 92 participants.
Following the detection of cancer signals, participants underwent various imaging and invasive procedures to confirm or reject the diagnosis. Of those 92, 35 participants were diagnosed with 36 cancers, nearly half in early stages — Stage I or II.
Among the confirmed cancers, 71% (25/35) of participants had cancer types with no routine screening available.
The cancer signal prediction had 97% accuracy and directed physician clinical workup, leading to resolution of the cancer diagnosis in less than three months for most participants with a true positive signal (73%) and in less than two months for half of them.
The developer of the Galleri test, which is not yet approved by the US Food and Drug Administration (FDA), says that it detects the cancer signal across more than 50 types of cancer, including those that are difficult to detect early, such as oesophageal or pancreatic cancer.
In 2020, England’s National Health System (NHS) announced a major Galleri test trial involving 165,000 people aged 50 to 77 who had not been diagnosed or treated for cancer in the last three years. The results of the trial are expected next year.
Excessive risks related to tests
Miglė Janeliūnienė, a laboratory medicine physician at Vilnius University Hospital Santaros Klinikos, who was not involved in the study, says that the PATHFINDER research design and conclusions look reliable.
“Researchers say that 71% of cancers would not have been detected with usual screening methods. Moreover, most cancers were detected at an early stage. And that is associated with a greater chance of successful treatment. However, the key challenges to the wide use of the method might be its complexity, the price of the test and the following additional testing, as well as the risks of false-positive results for a patient,” she said to Healthnews.
According to Janeliūnienė, MD, patients who received false-positive cancer signals could have possibly faced excessive risks related to radiology tests, such as radiation in computed tomography, and invasive tests, such as endoscopy and biopsy, involving risks of bleeding and risks related to anesthesia.
“Impact of psychological stress is also important. A patient who was not diagnosed with cancer might still wonder why their signal was positive, i.e., most likely, there is a change in their DNA methylation level. And that is related not only to the risk of cancer but also the risk of other illnesses, such as heart diseases.
On the one hand, it can encourage the patient to get carefully screened; on the other hand, it can contribute to developing anxiety and depression,” Janeliūnienė said.
She says that currently, in clinical practice, there is no blood test that can generally detect a cancerous process in the organism. However, certain blood tests are used in diagnosing the disease.
For example, the number of white blood cells, an erythrocyte sedimentation rate, or a lactate dehydrogenase in the blood tests allow one to suspect cancer but does not confirm the diagnosis.
Janeliūnienė says tumor marker tests can be used to detect certain types of cancer, as they look for specific substances related to particular cancers. However, the results of tumor markers tests are evaluated only in combination with those of other tests, such as biopsy or radiology.
According to the American Cancer Society, 1 in 2 men and 1 in 3 women will be diagnosed with cancer in their lifetime.
The recent report from the American Association for Cancer Research (AACR) reveals that more people than ever are living longer and more fulfilling lives after cancer diagnosis in the US, as the number of cancer survivors exceeded 18 million this year. And yet, an estimated 600,000 American lives will be lost to cancer in 2022.
NHS England. Galleri Trial.
AACR. Cancer Progress Report 2022.