Last week researchers announced they had created a simple test that could diagnose some cancers in under 10 minutes with only a drop of saliva. But what exactly does this mean for cancer diagnosis? And how can we be sure the test is accurate?

Who developed it?

The research team is led by Professor David Wong, a professor of oncology at University of California, Los Angeles. Wong presented his findings to the 2016 American Association for the Advancement of Science in Washington DC.

The team have been creating a method that detects tumour DNA that circulates in body fluids like saliva and blood.

How exactly does it work?

Dubbed a “liquid biopsy”, the test looks for genetic mutations in a tiny drop of saliva.

“We need less than one drop of saliva and we can turn the test around in 10 minutes,” he told the AAAS.

Wong also explained the test produced enough information to allow an accurate diagnosis as soon as a tumour develops.

Wong expects the test to be approved by the Food and Drug Administration in America within two years and hopes within 10 years it will be available in the UK. Saliva tests are set to be clinically tested in China later this year.

When can we get it?

Not for a long time. But it’s a promising sign for cancer research and survival rates on our soil, Professor Sanchia Aranda, CEO of Cancer Council Australia, told Crikey.

“The interesting and promising thing about this sort of molecular diagnostic test using saliva is the potential to detect cancers earlier, which could ultimately help improve Australians’ chances of surviving cancer,” she said.

Aranda explains that while we currently have screening tests available for cervical, breast and bowel cancer, there are a number of cancer types that have “vague symptoms and are therefore often picked up later, when the disease is at an advanced stage and more difficult to treat”.

But she cautions that “a lot more research is required before we reach that point”.

How accurate is the test and where do you take it?

Wong and his team assert that early results from lung cancer patients suggest the test has “near-perfect” accuracy and will cost the patient little over $30.

According to Wong, the test can be done in a doctor’s office while the patient waits or “it can be implemented by the patient themselves in a home check, dentist or pharmacy”.

Let’s say I buy a cancer-testing kit from the pharmacy, I test my saliva and it says I have cancer. Then what? 

According to Aranda, “it’s important to remember that it wouldn’t be a ‘one-stop-shop’ test”. The test does not provide information on how aggressive the cancer may be, how far advanced it is or the best treatment plan to follow. A visit to a doctor is the inevitable next step.

Does the test cover all cancers?

At the moment, researchers only have an established lung cancer test and are in the process of creating an oral cancer one too.

Assuming it eventually becomes available, how often should we be tested? Every year?

The test is not necessarily for every hypochondriac with the sniffles.

“Evaluation will also need to be undertaken to determine who the test should be offered to — for instance, it would probably be most suited to individuals with a higher risk of cancer, rather than being offered at a general population level,” Aranda said.

What are the benefits and drawbacks to this approach?

In addition to its cost-effectiveness and its non-invasive method of diagnosis, Wong believes the biggest benefit of this approach is early detection.

“Early detection is crucial. Any time you gain in finding out that someone has a life-threatening cancer … the better,” he said.

Oral cancer typically is not detected until later stages of the disease when the patient starts to exhibit symptoms.

Aranda agrees: “It can be used to pick up cancers before they would cause any problems for the individual.”

Although Wong hopes that “down the road it might be possible to test for multiple cancers at the same time”, Aranda is careful to emphasise the test does not replace a doctor visit: “Once the signs of cancer are detected, further testing would need to be undertaken to determine the exact nature of the cancer, in terms of size and location, and in order to determine the best treatment.”

Peter Fray

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