A new study from the UK could change how we find cancer. The NHS-Galleri trial is the first of its kind. It may change how we think about cancer screening. Instead of looking for one cancer at a time, this trial tests a single blood test. This test can look for more than 50 types of cancer at once.

This article will explain the trial, its importance, and what it could mean for the future of cancer care.

The Problem with Today’s Screening

We have made progress in fighting cancer, but there is still work to do. Many people are diagnosed with cancer when it is already at a late stage. This is because we do not have good screening tests for most types of cancer.

Our current national screening programs only check for a few types of cancer, like breast, colon, and cervical cancer. These cancers are important, but they only cause about 17% of all cancer deaths in the UK. This means we often wait for symptoms to appear for most cancers before we can do anything.

When symptoms appear, the cancer has often spread. This makes it much harder to treat. The NHS-Galleri trial hopes to change this. It wants to see if a single blood test can find many cancers early. This is when treatment works best.

What is the Galleri Test?

The test in the study is called the Galleri test. It was created by a company called GRAIL. It is a liquid biopsy that looks for small bits of DNA from cancer cells. This DNA is called cell-free DNA (cfDNA). The Galleri test uses a special method to find DNA that has been changed in a way that is unique to cancer.

A great feature of this test is that it can not only find a cancer signal but also often find where the cancer is coming from. In early studies, the test correctly identified the location of the cancer in almost 89% of cases.

This is very helpful. If a doctor knows where to look, it makes follow-up tests and treatments much easier and faster.

But the test is not perfect. The study’s authors note that the Galleri test is more likely to find cancer when it is at a later stage. This is when there is more cancer DNA in the blood. For example, in earlier studies, the test found only about 17% of Stage I cancers.

However, it found a remarkable 90% of Stage IV cancers. Even so, the authors believe a test that finds just 20% of all early-stage cancers would be more helpful than one that finds 80% of a single type of cancer.

Why this Trial is Different

The NHS-Galleri trial started in August 2021. It is unique for two main reasons. First, it is the first double-blind cancer screening trial of its kind. This means that neither the participants nor the doctors knew who was getting the Galleri test. The only exception was if a person in the testing group had a positive result. At that point, they would be “unblinded” to get further care.

This is a crucial step. It ensures the results are not biased by people changing their behavior or doctors treating patients differently.

Second, the trial is not mainly looking at whether the test saves lives. Instead, it is seeing if it reduces the number of late-stage cancers (Stage III and IV). This is a big change from how most cancer screening trials are done.

Traditionally, a trial’s main goal is to show a decrease in cancer deaths. This can take a very long time, sometimes 10 to 15 years or more.

The study’s authors argue that using late-stage cancer as the main goal will give them results much faster, in about four years instead of seven to nine. This is important because technology is changing so quickly. A test that takes 15 years to prove itself might be old news by the time the results are in.

The researchers think that if a test can reduce late-stage cancers, it will likely reduce cancer deaths as well. They point to other studies that show a clear link between reducing advanced cancers and reducing cancer deaths.

The trial will still look at cancer deaths, but it will be a secondary outcome. This will be reported about two years after the primary results.

The Trial’s Big Questions

The NHS-Galleri trial wants to answer several important questions. The main one is, “Can a multi-cancer blood test actually provide real-world benefits?” It’s one thing for a test to find cancer in a lab. It’s another for it to be useful in a real screening program with millions of people.

One of the biggest worries about a multi-cancer test is the number of false positives. This is when a test says you might have cancer, but you don’t. A false positive can be very scary. It can also lead to unnecessary follow-up tests, like biopsies, which can be invasive and stressful.

The Galleri test has a high specificity of 99.5%. This means it is very good at not giving a positive result when no cancer is present. While this is a good number, in a country as big as the UK, a 0.5% false positive rate could still mean about 100,000 false alarms each year. This would happen if everyone between the ages of 50 and 77 were screened annually.

The authors put this into perspective. In England, there are already nearly 3 million urgent referrals for suspected cancer each year. 94% of these do not lead to a cancer diagnosis. The extra 100,000 false positives from the Galleri test would be a lot. But they would be less than 4% of the current total number of negative cancer investigations. If this small increase in false positives leads to a big drop in cancer deaths, the authors say it would be worth it.

Another concern is health equity. The study points out that people who are more disadvantaged or from certain ethnic minority groups are more likely to be diagnosed with late-stage cancer. A new screening test has the potential to help these groups the most.

However, these are often the same groups who are less likely to join traditional screening programs.

The authors say a new program would need to focus on reaching these communities. This would prevent making health inequalities worse. The NHS-Galleri trial has been praised for its success in getting a diverse group of people to participate.

This shows that it is possible.

A Look at the Results So Far

The trial has already completed its recruitment of 140,000 people. It has also finished the third round of blood sample collections.

The final results won’t be out until 2026. However, there was a limited “closed report” of the first year’s data.

This was not a full report of the main results. It did not include information on late-stage cancer cases or deaths.

Based on this limited data, NHS England decided not to move forward with a large-scale pilot program of the test just yet. The study’s authors explain that the first-year data from a screening trial is often not very telling.

Many of the cancers found in the first year are “prevalent” cancers. These were already present before the trial began. So, a major reduction in late-stage cancers is not expected right away.

The authors mention a well-known lung cancer screening trial. It also found no reduction in late-stage cancer in its first year. But it went on to show a clear benefit after three rounds of screening.

This is why the researchers think it is so important to see the trial all the way through. The real benefit, they say, will be seen after several rounds of annual screening. The trial is now in the follow-up phase.

The world is waiting to see the final results.

What’s Next?

The NHS-Galleri trial is an important first step. The authors say that if the trial shows a big reduction in advanced-stage cancer, it will be a “transformative” moment in cancer screening.

They predict that a test like Galleri could reduce cancer deaths by as much as 17% in people who get screened every year.

If this is true, it would save thousands of lives. It would be a huge step forward in the fight against cancer.

If the results are positive, the authors argue that we should not wait for the long-term mortality data to come in.

They believe that society could gain two years and save thousands of lives by starting a pilot program sooner. Historically, it has taken 10-15 years for a new screening program to be fully put in place after a successful trial.

The authors believe that in the case of a multi-cancer blood test, waiting could be a deadly mistake.

The trial’s design and the potential of the Galleri test show a new way of thinking about cancer.

By moving faster and looking for a different kind of evidence, the NHS-Galleri trial could be a model for future research.

This could lead to a future where a simple blood test is part of a regular health check. This would give doctors and patients a powerful new tool in the fight against cancer.

Source:

JNCI: Journal of the National Cancer Institute, djaf218, https://doi.org/10.1093/jnci/djaf218