George Hanna.Credit: EAES
Diagnosing pancreatic cancer at an early stage is challenging. The signs and symptoms — including abdominal pain, weight loss and indigestion — are often non-specific and shared with benign diseases. In England, 39% of people receive a diagnosis only once the cancer has spread to other areas of the body, such as the liver or lungs. George Hanna, an oesophageal surgeon and head of Imperial College London’s department of surgery and cancer, spoke to Nature about a breath test designed to detect the malignancy early.
Why are you developing a breath-based test?
I was inspired by nature. I knew that dogs could smell cancer by detecting chemical changes produced by molecules exhaled by their owners. I wondered if we could mimic this. Pancreatic ductal adenocarcinoma (PDAC) — the most common form of pancreatic cancer — is diagnosed using imaging, such as computed tomography (CT) scans, and biopsies, which are invasive procedures. The whole process can often take weeks. In the United Kingdom, only people who meet strict referral guidelines for cancer can be tested, which excludes people with vague symptoms. And, at the time of diagnosis, fewer than 10% of people with pancreatic cancer still qualify for surgery, which is the only curative option.
Nature Outlook: Pancreatic cancer
But if someone walks into a hospital or a pharmacy complaining of any of the vague symptoms that are indicative of PDAC, then they could do a breath test right there. It takes about five minutes to do, and the aim is that results would be available within 24 hours of reaching the laboratory. If it’s positive for PDAC, the person is referred for further testing to confirm the result. The breath test is quick, easy and non-invasive, and if we can use it to find people with PDAC earlier, then they would have more treatment options and a better chance of surviving. Modelling studies show that using the breath test this way could save the UK National Health Service £155 million (US$202 million), annually.
How does the test work?
The test works like an alcohol breathalyser. The person breathes into a sterile bag. The breath sample is then transferred into a tube that contains a sorbent, which traps molecules known as volatile organic compounds (VOCs). This tube is then taken to the lab, and its contents are analysed for specific compounds using mass spectrometry.
The breath test for PDAC looks for VOCs that come from the cancer itself, the response of the body to cancer (which is present at an early disease stage) and the bacteria associated with the cancer. These bacteria are different from those found elsewhere in the body and they produce unique VOCs during metabolic processes. Some of the VOCs help us to discriminate between cancer and no-cancer, whereas others are specific to pancreatic cancer. Our model looks at the compounds in the sample and suggests whether it is cancer or not.
A breath test for pancreatic cancer, which involves breathing into a sterile bag, is in development.Credit: Jeff Moore/Pancreatic Cancer UK
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