Are there any side effects to the capsule sponge test?

As with any innovation, it’s important to understand potential risks. The capsule sponge has been designed to be easy and pain free to swallow and, so far, trials and pilots across more than 20,000 people haven’t shown any serious side effects. 

Results from a patient experience study showed high participant satisfaction, with 8 in 10 people willing to have the procedure again.

But some participants did report discomfort. There were no issues with the capsule in the stomach, but some found that the rough texture of the sponge could cause some gagging or a mild sore throat. The sore throat typically subsides after a few hours, but if pain persists it can easily be relieved with simple pain relief such as paracetamol.

There is a very small risk (less than 1 in 2000) that the sponge detaches from its string or that a nurse may not be able to remove it. In the unlikely event that this happens, the sponge can be safely removed through an endoscopy. 

We started funding BEST2, the second trial of the capsule sponge test in 2010, alongside the National Institute of Health and Care Research (NIHR) Cambridge Biomedical Research Centre.

The trial, which recruited 1,110 participants with Barrett's oesophagus or heartburn symptoms, was crucial for establishing the safety and accuracy of the capsule sponge test as a screening and monitoring tool.

We took the next step in 2017, when we began funding BEST3 alongside the NIHR.

This trial, which recruited 13,000 patients experiencing heartburn, went on to show that the test can pick up 10 times more cases of Barrett’s oesophagus than GP standard of care.  

Remarkably, it also picked up a number of early-stage cancers. 

“The great thing is if you find this disease [Barrett’s oesophagus] early, if it begins to change towards cancer, you can completely treat it and cure it,” says Fitzgerald.

“And the treatment is a super simple outpatient procedure carried out through the endoscope to remove the early cancer. So, there’s no removal of the oesophagus, which is what we have to do if the cancer is diagnosed at a more advanced stage.” 

Soon after BEST3, the COVID-19 pandemic began putting pressure on endoscopy services, leading to growing backlogs. But a silver lining emerged for the capsule sponge as the NHS began to pilot it in the wider health system. 

During this period, around 10,000 patients were able to receive the test, either for routine monitoring of Barrett’s oesophagus or to investigate chronic reflux symptoms. 

The results of the pilot were clear. The capsule sponge test demonstrated distinct advantages, proving to be simpler and more effective than endoscopies, with a faster turnaround for results – saving the NHS £127 per procedure. Analysis also shows that by enabling earlier cancer detection, the test has the potential to reduce broader health-care costs. 

We're now funding the final trial, BEST4, again alongside the NIHR. The trial is divided into two parts. One, BEST4 Surveillance, is looking to see if the capsule sponge test can accurately replace endoscopies as a way of detecting and monitoring people who have Barrett’s oesophagus. 

The second part, BEST4 Screening, could impact many more people. It’s the critical step for determining whether this tool could be used to screen people with heartburn for Barrett’s oesophagus and oesophageal cancer. 

“To get this out as a national screening programme then we have to show [that] not only does the test find more cases of Barrett's oesophagus but that we can actually reduce the need for people to have chemotherapy and surgery, and also stop people dying from oesophageal cancer," says Fitzgerald.

So far, over 5,000 people have taken the test as part of BEST4 Screening. In total, the trial is aiming to recruit over 120,000 patients over the age of 55 on long term treatment for heartburn, a third of whom will be selected to use the capsule sponge test. 

“We’ll get an idea of whether this is successful in around five years because we should see whether we’re starting to find more cases of early-stage cancer of the oesophagus, but it will be around 12 years before we get the full results,” Fitzgerald says. 

Still, we might not have to wait that long before people who aren’t on the trial could start benefitting. Fitzgerald has had promising conversations with funding agencies and policymakers about beginning to roll the test out sooner if the early results are strong enough. 

Though small in size, the capsule sponge test could be a mighty breakthrough in early cancer diagnosis. We already know that it provides doctors with an efficient means to detect Barrett’s oesophagus. Now we’re finding out if we can use it to save lives too.