A new genetic test has been developed that can detect early signs of mouth cancer.
The qMIDS test measures the activity of 16 genes from a piece of biopsy tissue less than half the size of a grain of rice.
It can show whether patients with mouth sores or ulcers possess pre-cancerous cells.
The test had a cancer detection rate of up to 94% when used on more than 350 head and neck tissue specimens from 299 patients in the UK and Norway.
Mouth, or oral cancer, affects more than 6,200 people each year in the UK.
One of the main symptoms is mouth lesions, such as sores and ulcers. But these are very common and mostly benign - only 5% to 30% may develop into cancers.
Lead researcher Dr Muy-Teck Teh, from the Institute of Dentistry at Queen Mary, University of London, said: "A sensitive test capable of quantifying a patient's cancer risk is needed to avoid the adoption of a 'wait-and-see' intervention.
"Detecting cancer early, coupled with appropriate treatment, can significantly improve patient outcomes, reduce mortality, and alleviate long-term public healthcare costs."
The findings are published in the International Journal of Cancer.