Doctors at a London hospitalare evaluating a new method for detecting cervical cancer, which could eventually replace the cervical smear test. "It gives an extremely accurate picture of the cervix," says Tim Mould, a research fellow at the Whittington Hospital, who is to spend the next two years testing 2,000 women with the new electronic device. And the result can be given to the woman immediately.
The idea behind the new electronic approach is that, depending on whether they are healthy, cancerous or showing the early changes that could lead to cancer, the cells behave differently in response to certain kinds of stimulation. The electronic device uses two types of stimulation: light frequencies and low-voltage electrical impulses.
A pen-like probe applied to the cervix emits both the electrical impulses and the light waves, and senses the way the cervical cells respond. It is wired to a computerabout the size of a portable typewriter, to which it transmits its findings. The computer has been programmed to use this data to "recognise" different types of tissue and to categorise them and it displays the results instantaneously on its small screen. "It works by pattern recognition - we tell the probe that a certain signal equals a certain abnormality," says Mr Mould.
To have the test you still have to lie on your back and submit to the speculum. But instead of taking a scraping of cells from the cervix, the doctor runs the probe over its surface.
"You won't feel the probe but you might feel a smear being taken - that can be painful. With the probe the voltage applied is well below the level at which you would feel it."
The new method has other advantages over smear tests. An instant result, even if the news is not good, is better than a phone call or an impersonal letter, sometimes weeks later.
It is much simpler. Smear tests involve around 30 steps, from taking the sample from the right place and putting it on the slide correctly to interpreting it in the laboratory and sending out the results. Staff in cytology laboratories see thousands of slides every day, the vast majority of which are normal.
Interpretation can be variable, abnormalities can be missed. Thousands of British women have now had their smear tests questionedin well- publicised "recalls" after mistakes have come to light, often because a cancer has been detected in a woman who had a "clear" result.
With the new method, called the Polarprobe, there are fewer steps and less potential for error. "It's completely objective - the machine tells you the result, so it is likely to be more accurate than the smear test," says Tim Mould. It has been extremely well accepted by women so far, he says, and he believes it will increase the number of women attending for screening.
Professor Albert Singer, who sees thousands of women each year at the Whittington Hospital's clinic for women with abnormal smears, says that the biggest problem with the smear test is the anxiety involved in waiting for the result and, if this is positive, in being referred to a hospital clinic for further investigation. This involves examination of the cervix by colposcope, a means of magnifying the cervix to identify any abnormal areas.
"The psychosexual trauma of being referred to a consultant is so great that we have been looking at ways of keeping women out of the clinic wherever possible," he says. "For instance, for women who have a mildly abnormal smear we have tried a technique called cervicography. Nurses, who also counsel the women beforehand, take photographs of the cervix and then we look at the slides. Women feel more comfortable with that."
The accuracy of the Polarprobe could also reduce the number of women referred for colposcopy unnecessarily, says Professor Singer. "The Polarprobe will make an enormous difference - and anything that makes the screening process more consumer-orientated, such as instant read-out of the result, is a big step forward."
The Polarprobe was invented in Australia, where two lateral-thinking gynaecological oncologists formed a research and development company called Polartechnics, utilising the skills of a number of physicists and rocket scientists from eastern Europe. Work began on the Polarprobe in 1987 and the model now being evaluated is the sixth prototype.
A paper describing preliminary research was published in the International Journal of Gynecological Cancer last year and the next stage is a large- scale study to assess its clinical value.Professor Singer, who heads one of the largest colposcopy clinics in Europe, and Tim Mould have agreed to conduct the clinical research.
They will use the Polarprobe on 1,000 women referred to the Whittington with abnormal smears and a further 1,000 women attending Well Woman clinics and a sexually transmitted diseases clinic. This group of women will have no known cervical abnormality. Staff will give them a smear and use the probe.
A possible future development is that the same technology could be used to detect other cancers. Already in Australia the Polarprobe team is investigating its use on skin cancer - applying the probe to suspect skin lesions to identify whetherthey are malignant. The detection of breast cancer is anotherpossibility.
``It offers the chance of a better test than the mammogram, which is expensive, involves X-rays and is used only on women over 50," says Mr Mould.
However, he is well aware that by singing the praises of the Polarprobe he could be drawing attention to the shortcomings of the smear test and perhaps deterring women from going for smears.
"Smear testing has dramatically reduced the number of deaths from cervical cancer," he stresses. It is still true that most women who develop cervical cancer have never had a smear test. And for now, although it is not perfect, it's all we have.Reuse content