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Pill-size camera may make cancer diagnosis easier

Monday 14 January 2013

Recent news coverage has heralded the arrival of a new “camera you can swallow” that “could help detect early stages of cancer of the oesophagus”.

The high-tech device, about the size of a large vitamin pill, uses optical lasers to photograph the insides of the stomach and oesophagus in detail. It is hoped that this new investigative technique may help spot early signs of cancers of the digestive system, such as oesophageal cancer (also known as cancer of the gullet). The researchers suggest the cancer camera is a quick, simple and pain free imaging method that patients may prefer to endoscopy – the current method of investigating the lining of the digestive system – where a thin tube with a camera and a light source at the end is passed down into the oesophagus.

Endoscopies have a number of practical disadvantages, including:

  • they are often performed under sedation, so they can be time-consuming
  • they require specially-trained staff, so they can be expensive to carry out (specialist staff usually want specialist pay rates)

Because of these disadvantages, diagnosing oesophageal cancers can place a strain on resources.

However, if this new technology is proved to be quick, safe and effective (and that is a very big ‘if’) then the diagnosis process may become a lot easier.

Another advantage is that the camera can provide more detailed images than current investigative methods such as endoscopy.

New technologies are an integral part of medical advances. However, it appears the camera was only tested in a very small number of patients with a specific disease, so it will need to be far more thoroughly tested for safety and effectiveness before it can potentially be adopted in the UK.

What is the basis for these current reports?

A short technical description of the new technology was produced by researchers from Harvard Medical School and was published today in the peer reviewed scientific journal Nature Medicine.

The research was funded in part by grants from the US National Institutes for Health.

What is the cancer camera?

The cancer camera is a new way of investigating the lining of the gastrointestinal tract for signs of diseases such as cancer, or abnormal cells that are likely to go on to become cancerous.

The cancer camera, or “optomechanically engineered pill”, is a small (12.8mm by 24.8mm) high-tech pill-shaped laser camera that is attached to a thin string-like wire, called a tether. The pill, which is swallowed, captures microscopic images of the lining of the oesophagus and gut at high resolution as it travels naturally through the digestive tract. The wire also allows an operator to control the position of the pill in the digestive tract to look at specific areas of interest.

Once the pill has got to the area of interest (such as the base of the throat – to investigate problems such as dysphagia) it can be pulled back slowly by the tether. On its way back out the body the camera continues to take images. Multiple swallows and retrievals can be used to build up a detailed and comprehensive picture. All the visual information is fed back to a processing console that builds the information into a detailed 3D image that a doctor can review for signs of disease such as oesophageal or stomach cancer.

How does it work?

The camera uses a near infra-red laser that rotates at high speed to take 360 degree high definition images of the surrounding tissue. The images can be transmitted back to a monitor in real time and can also be pieced together after the procedures for further scrutiny by medical professionals.

After the procedure, the pill can be disinfected and used on other people.

Why is this new technology needed?

Diseases of the gastrointestinal tract (such as oesophageal cancer) are currently commonly diagnosed by endoscopy. This involves a doctor passing a thin, flexible tube with a camera on the end (endoscope) down your throat to your stomach looking for abnormalities along the way. The doctor can also pass instruments down the centre of the tube to extract a small amount of tissue from areas that appear abnormal. These cells are then analysed in a laboratory to see if they are cancerous.

While endoscopy is a very useful tool, it is not perfect. For most procedures the subjects are sedated, requiring a specialist setting, equipment and medical staff to monitor for adverse reactions; this makes endoscopy relatively time consuming and costly. In addition, the endoscope can only visualise the most superficial layer of cells at the sides of the oesophagus and is unable to detect less obvious or slightly more hidden abnormal cells.

Advantages and disadvantages?

The researchers indicate that the main advantages of the camera over endoscopy are that:

  • using the camera does not require highly trained staff
  • the procedure is relatively quick
  • the patient does not need any sedation

Furthermore, the image produced by the camera is more detailed than that obtained through endoscopy, which could allow it to detect things that endoscopy might miss.

The obvious disadvantage of this approach is that if the camera identifies an abnormal area, there is no way of taking a small sample of the tissue (biopsy) to confirm this, which can be done using endoscopy.

Therefore, if an abnormal area of cells was detected by the cancer camera, the chances are that the patient would then need an endoscopy and biopsy as the next step of the investigation.

Has it been tried in people?

The publication suggests that the new technology has only been tested in 13 people. It will need to be tested in more people to prove that it is safe and useful before it can be adopted for widespread use in this medical field.

The small study of 13 subjects included seven healthy volunteers and six volunteers with known Barrett's oesophagus. This is a disease where the cells of the lining of the oesophagus are damaged and changed by acid reflux from the stomach. While the damaged cells are not cancerous in patients with this disease, there is a heightened risk they could develop into cancer cells.

Researchers found that the average transit time for imaging a 15cm length of oesophagus was just under a minute (58s). For four imaging passes (two up and two down), resulting in four complete data sets, the entire procedure lasted an average of approximately six minutes (6min, 18s) from capsule insertion to extraction. There were no complications reported.

After the procedure, the majority (12/13) of the subjects reported that they would prefer tethered capsule endomicroscopy to conventional endoscopy.

The researchers concluded this was a quick and effective method of detecting pre-cancerous cell abnormalities, such as those present in people with Barrett’s oesophagus.

What are the implications?

The main reason that this device made the news is that it potentially offers a quicker and cheaper method of investigating or screening for diseases of the gastrointestinal tract, such as Barrett’s oesophagus.

Currently, most countries don’t screen healthy individuals for these types of diseases as the current method, usually endoscopy, is not cost effective as part of a national screening program.

This is also because the diseases are usually relatively rare so you would have to screen a large number of people (potentially causing harm through the investigation) to detect just one person with the disease.

This may do more harm than good for the majority of people.

However, any new technological alternatives that appears safer, cheaper, or quicker attracts a lot of interest as it may swing the balance in favour of a national screening program.

The more likely option is that such as test could be used to investigate suspected disease in symptomatic people rather than used to mass screen healthy individuals.

Great news as the new device is, it is important to remember that this technology is very much in the early days of development and needs to be properly and thoroughly tested in larger groups of people to ensure it is actually more cost effective and safe compared to current techniques. This may take many years to establish, but the proof of concept seems promising.

Analysis by NHS Choices. Follow Behind the Headlines on twitter.

Analysis by Bazian
Edited by NHS Website

Links to the headlines

Pill-sized scanner images gullet

BBC News, 13 January 2013

The camera you can swallow: New capsule could help detect early stages of cancer of the oesophagus

Daily Mail, 13 January 2013

Links to the science

Gora MJ, Sauk JS, Carruth RW, et al.

Tethered capsule endomicroscopy enables less invasive imaging of gastrointestinal tract microstructure

Nature Medicine. Published online January 13 2013