Has our best diagnostic tool been right under our nose?

Dogs have long been used to assist us with an array of medical problems but it now seems that a canine nose could also be used to help diagnose cancer.

A study by the Humanitas Clinical and Research Centre (HCRC), published in the Journal of Urology , has revealed that two explosive detection sniffer dogs were able to identify urine samples of men with prostate cancer with a 98.6% accuracy rate.

How does it work?

Dogs’ noses can detect cancer because of their incredible sense of smell. A dog has approximately 125 to 300 million scent glands which means that their sense of smell is around 1,000 to 100,000 times more sensitive than a human. So what do they smell?

The human body emits hundreds of odorous and non-odorous volatile organic compounds (VOC) through our breath, sweat, skin, urine and faeces. These compounds are originally secreted by the cells in our body and are not detectable by the human nose but they can be smelt by dogs. The VOCs produced vary according to a person’s age, diet, sex and physiological state. When we get ill; contract an infection; or develop a pathological disease, the body produces new disease-specific VOCs and causes the ratio of VOCs in our body to change, thus altering our body odour.

As part of their training, the bio-detection dogs in the HCRC study were taught to identify cancer samples by sniffing out the cancer-specific VOC in the urine sample of a patient with prostate cancer. The dogs were trained using a clicker which, when clicked, signified that they have correctly identified the cancer sample. This method of training works on the basis that the ‘click’ is associated to a reward. Over a period of time the dogs learnt that they only got a treat when they identified a cancer sample.

Work has been done to identify cancer-specific VOCs for other types of cancer. Using sensitive instruments, researchers have been able to measure different patterns of VOCs in breath samples from cancer patients compared to individuals who are cancer-free. A study of breast cancer showed a unique combination of hydrocarbons in the breath samples of patients diagnosed with breast cancer. Likewise a lung cancer study showed that some of the VOCs secreted from cultured lung cancer cells were also present in breath samples of lung cancer patients.

It must be remembered that these studies are at an initial stage. Much more research will need to be done before this can be considered a reliable diagnostic tool. The HCRC study concluded that further research is needed to discover how the dogs would perform in tests where it is unknown whether the subject has prostate cancer. However, early results indicate that dogs will play a key role in the study of cancer-specific VOCs and the development of synthetic noses

Why is the study helpful in improving earlier diagnosis?

The theoretical potential for disease-specific odours to aid diagnosis has been recognised for many years. Identifying these compounds so they can be used as biomarkers for diagnosing cancer would be a significant step towards making this a reality.

Early diagnosis of cancer is important as it usually increases a patient’s chance of a better outcome and surviving the disease. This is because the later cancer is diagnosed, the more advanced it becomes, and the higher the chance it has grown and spread to other parts of the body. This in turn limits treatment options. If a new, quicker and more accurate test can be developed as a result of the HCRC study, this in turn should lead to earlier diagnosis. However, even when effective diagnostic tests have been developed, sadly cancer may still be diagnosed at a later stage. This can be caused by a number of factors, such as having to wait for test results to come through. It can also be due to medical negligence, for example if there is a delay in referral to a specialist or for tests.

Cancer and medical negligence

In order to bring a successful claim for compensation for medical negligence, you need to show:

  1. That your medical care provider has breached their duty of care owed to you, for example, that they failed to recognise and/or investigate symptoms of cancer when they should have; and
  2. That this failure has caused your condition to become worse

Unfortunately we often hear of situations where there has been an avoidable delay in diagnosing cancer. Typically this relates to treatment provided by a General Practitioner (GP), as they are likely to be the first point of contact for people with troubling symptoms.

Claims for compensation may relate to:

  • Symptoms that have been dismissed or overlooked
  • A failure to refer for further tests at all or in good time
  • A failure to interpret test results correctly
  • A failure to investigate or monitor symptoms

The Future

The HCRC study provides real promise that VOCs could be used in the future to diagnose cancer earlier. Sadly symptoms of cancer can sometimes still be overlooked by medical professionals, missing opportunities for diagnosis even where more advanced tests are available. Any improvement in testing that can be done easily, at low cost and perhaps even by a GP themselves will help, but this does rely upon the GP recognising that the test is required because of the nature of a patient’s symptoms.