Laser probe enables early diagnosis of oral cancer

Each year approximately 43,000 people in the US are diagnosed with tumours of the mouth, pharynx and larynx, and most cases are not diagnosed until the cancer has reached an advanced stage.

‘There’s a lot out there about breast, prostate and brain cancer, but people are not so aware about oral cancer,’ said Laura Marcu, a professor of biomedical engineering at UC Davis. ‘People don’t think to look for it and there isn’t any routine screening.’

Marcu’s laboratory collaborated with Dr Gregory Farwell’s group in the Department of Otolaryngology at the UC Davis Cancer Center to develop the fibre-optic probe.

According to UC Davis, the probe stimulates molecules in the patient’s tissues with a laser. Some of these molecules naturally respond by re-emitting fluorescent light. The device detects and analyses this light using time-resolved fluorescence spectroscopy (TR-LIFS), which provides information about the types of molecules present.

During surgery, blood can distort the intensity of the fluorescence signal but not its duration. By using measurements of the change in fluorescence over time, surgeons can see the tumour margins. It is claimed they can do this even as they are cutting tissue.

Based on results in animal tests, Marcu and Farwell’s team recruited nine human volunteers from among patients who arrived at the UC Davis Medical Center for surgical therapy of the mouth, throat and larynx.

They compared readings from spectroscopy with biopsy samples from the same locations and found that the probe could accurately diagnose the cancer in the surgical environment.

The probe is similar to one that Marcu has already developed for use with brain tumours. In clinical trials, surgeons have used her technology to delineate the margins of tumours during surgery.

Details of the human oral-cancer study will be published in an upcoming issue of the journal Otolaryngology - Head and Neck Surgery.