Laser that can spot cervical cancer early
LASER beams could help detect cervical cancer at an early stage, say researchers from China. The new technique involves firing pulses of light, more of which is absorbed by cancerous cells than by healthy tissue.
The way the cancer cells react to the light means they can then be picked up on an ultrasound scan. The scan can show not only if someone has the disease, but also potentially how advanced it is.
More than 3,000 cases of cervical cancer are diagnosed each year in the UK, with around 1,000 women dying from it. Almost all cases are caused by the human papillomavi‑ rus (HPV), often spread during sex.
There are more than 100 types of HPV, many of which are harmless. But some can disrupt the normal functioning of the cells of the cervix and can eventually trigger the growth of cancer.
Cervical smear tests are used to screen for abnormal cells — and the results may lead to a physical examination (where the cells are examined in situ using a micro‑ scope) and then a biopsy. A CT or MRI scan is performed only if the biopsy suggests there is cancer. Although cervical screening — offered to all women over 25 — has led to a large drop in the numbers affected by cervical cancer and in deaths, lesions can be missed and visual examinations can also lead to unnecessary biopsies.
The new technology, known as photoacoustic imaging, requires neither a biopsy nor a smear test. It works on the principle that cancerous tissues (and possibly even pre‑cancerous cells) absorb more light than healthy tissue.
This is because of changes in cancerous tissue such as the formation of new, abnormal blood vessels and fewer collagen fibres (a tough, connective tissue). The cancerous tissue can then be picked up on an ultrasound scan because the extra energy absorbed from the light is converted into heat, which causes the cells to expand and affects the way sound‑ waves bounce back to the scan‑ ner, creating an image of the cells with cancerous changes.
Photoacoustic imaging could also identify the stage of the disease without a biopsy, say the research‑ ers. This is because the more advanced the disease, the greater the amount of light and energy absorbed by the cells; these areas then look even more pronounced on a scan.
The technique has so far been tested on tissue samples from 30 women — some with cancer and some who were healthy — which showed that it can distinguish between the two. ‘We have shown for the first time that photoacous‑ tic imaging has the potential to make better diagnoses and help save lives,’ say the researchers from Central South University, China. The study is published in Biomedi‑ cal Optics Express, the journal of the Optical Society of America.
THE same technology is also being investigated for detecting and moni‑ toring other cancers, including breast and skin.
Fiona Osgun, Cancer Research UK’s health information officer, said: ‘This small study is at a very early stage and we are a long way from knowing if this technique could diagnose cervical cancer. Cervical screening is the best way to detect cervical changes early before they develop into cancer.’
Meanwhile, a special red‑light laser could banish bad breath. Halitosis is typically caused by bac‑ teria in the mouth which produce unpleasant smelling chemicals as they break down food.
A team of researchers from the University Nove de Julho in Brazil found that low‑level laser light, which can kill bacteria, cut levels of bad breath‑causing chemicals by around a third in 60 minutes.
The light is used in conjunction with a special light‑sensitive dye on a patient’s tongue, in order to target the bacteria‑killing effects of the laser.