Capsule sponge testing and oesophageal cancer diagnosis

If you are a searching for information as a patient/carer, you may want to consider visiting our public facing information about capsule sponge testing.

What is capsule sponge testing?

Capsule sponge testing, sometimes called the ‘pill on a thread’, is a simple test used to help detect oesophageal cancer and its pre-cursor condition, Barrett’s Oesophagus, earlier. It has been tested in clinical trials funded by Cancer Research UK.

Oesophageal cancer is often diagnosed late. Earlier diagnosis improves the chances of survival. For example, around 75% of people diagnosed at stage 1 survive for 5 years or more, compared to just 6% when diagnosed at stage 4¹.

Capsule sponge testing is one approach that could support earlier detection and diagnosis. It works by collecting cells from the lining of the oesophagus, which can then be tested for abnormal changes. The capsule sponge devices most commonly used in the UK is Endosign and Cytosponge. Studies are underway across the UK to understand how this test can be used in different settings to support earlier diagnosis.

Want to learn more about recognising and referring oesophageal cancer? Read our two-page guide for health professionals in England and Wales.

How do capsule sponge tests work?

The test kit includes a small capsule containing a compressed sponge attached to a surgical thread. The test is usually carried out by a nurse, taking the following steps:

1. The patient swallows the capsule with water, which dissolves in their stomach releasing the sponge.

2. The sponge is retrieved after a few minutes by gently pulling on the thread.

3. As the sponge moves up through the oesophagus, it collects cells from the oesophageal lining

4. These cells are sent for analysis for markers of Barrett’s oesophagus or oesophageal cancer

Find out how the test is performed in this video:

Use cases for capsule sponge

The capsule sponge is being used, piloted and evaluated in a range of settings. Current and potential applications include:

• Triaging patients with reflux symptoms waiting for gastroscopy to prioritise those at higher risk of Barrett’s oesophagus and oesophageal cancer

• Surveillance in people with Barrett’s oesophagus to detect early signs of oesophageal cancer

• Targeted or proactive case-finding of Barrett’s oesophagus and oesophageal cancer in people at high risk in a primary or community care setting

In any of the use cases, if a positive result is found, gastroscopy will be required to confirm the diagnosis and disease severity.

The image below shows these uses across the diagnostic pathway for oesophageal cancer.

Capsule sponge pilot studies and national evaluations across the UK

Open the accordions below to find out more about different evaluations of capsule sponge testing across the UK. Information on implementation can be found in our 'What’s next for capsule sponge?' section.

Advantages and disadvantages of capsule sponge

Advantages

• Capsule sponge testing may improve patient experience, which could reduce did not attend (DNA) rates along the pathway

• The test is less invasive and quicker than gastroscopy

• The test does not require sedation and it can be performed in a community setting by different types of health professionals, including nurses

• High levels of patient and clinical acceptability have been reported¹⁵¹⁶¹⁷

• It has been proven to reduce endoscopy workload - by identifying and removing those at low risk of Barrett's Oesophagus or oesophageal cancer from endoscopy wait lists

• It has shown potential cost savings vs standard care in evaluations²³¹²

Disadvantages and limitations

• Barrett’s oesophagus, as a known precursor to oesophageal cancer, can be missed. Evidence shows around 19-27% of cases are not detected by capsule sponge¹⁵¹⁸, although this is reduced to around 10% in patients with a repeat test [18]). Therefore, safety netting patients with a negative capsule sponge result but concerning symptoms is vital

• The device is only validated for oesophageal pathology detection, so other investigations are required if gastric pathology is suspected.

• Evidence is still developing on the capsule sponges’ impact on improving longer-term oesophageal cancer outcomes

• Some tests may need to be repeated if swallowing is incomplete

• The most common side effect is a sore throat (also a side effect from gastroscopy)

• In very rare cases (less than 1 in 5,000)⁴, the sponge can detach from the string and remain the stomach. If this happens, it needs to be removed via an endoscopy

What’s next for capsule sponge?

Capsule sponge testing is at different stages of adoption across the UK, with ongoing research and evaluation continuing to shape how and where it is used in practice.

• Capsule sponge for triaging patients with reflux is already in routine practice in many parts of the UK. Health systems across the UK are still working through adapting pathways for full adoption across use cases.

• Capsule sponge is available nationally in Scotland and Wales. In England, the test is available via national supply routes with funding in place. A defined implementation pathway is not yet established in Northern Ireland.

• The BEST4 trial (2022-2035), jointly funded by Cancer Research UK and the National Institute for Health and Care Research, is assessing capsule sponge in people taking long-term medication for heartburn¹⁹. It is assessing whether screening using the capsule sponge can prevent deaths from oesophageal cancer and reduce morbidity from chemotherapy and surgery to remove the oesophagus as a result of earlier diagnosis.

• The trials is also aiming to establish optimal intervals for use in Barrett’s surveillance and whether people with low-risk Barrett's can be monitored by serial capsule sponge testing.

• For both triage and surveillance use cases, a NICE technology appraisal will conclude in 2027.

Preparing health systems

As evidence and guidance continue to develop, there are several practical steps health systems can take to prepare for wider use:

Innovation

Emerging research is exploring how artificial intelligence (AI) could support analysis of capsule sponge samples. This has the potential to reduce demand on pathology services and improve efficiency^20212223. Further research is needed to understand the role AI could play in detecting Barrett’s oesophagus and oesophageal cancer.

Other resources

• Health professional guide to diagnosing oesophageal cancer earlier (England and Wales)(PDF, 150 KB) (June 2025)

• Barrett’s Esophagus evidence overview (Fitzgerald RC. New England Journal of Medicine, 2026)

• Public facing information about capsule sponge testing.