New screening test could prevent more cervical cancer
A new test could be a more effective early warning system for preventing cervical cancer than the traditional smear - according to Cancer Research UK scientists.
A report, published in The Lancet1, says that the test, which is designed to detect a virus that causes almost all cervical cancer, is far more sensitive than the smear.
The results of the study, involving 11,000 British women aged 30-60, suggest that this test has the potential to become the main screening tool for preventing cervical cancer.
Scientists found that the test for Human Papilloma Virus (HPV) detected 97 per cent of significant cervical abnormalities compared to 76 per cent for the smear.
Professor Jack Cuzick, Cancer Research UK's Head of Epidemiology, based at Queen Mary, University of London, led the study. He says: "Our findings are so promising that a pilot project should now be set up to see how the new test should be integrated into the existing cervical screening programme."
HPV infection is extremely common, but most infections disappear without causing any disease and without the need for treatment. Only when the infection persists can it cause cervical cancer.
The study focussed on how best to use the test's greater sensitivity without over-treating infections that would otherwise be cleared naturally by the body's immune system.
The authors suggest that HPV testing could be the primary screening test and smears would be done (using the remainder of the sample) only in women who tested positive for the virus. If that smear were negative, the study showed that it was safe to monitor these women by re-testing a year later to see if the infection had disappeared.
Scientists also believe that this approach could reduce the number of women who are needlessly referred to hospital clinics because of false positive smear test results.
Prof Cuzick says: "We have known for decades that Human Papilloma Virus is the primary cause of cervix cancer. We now have a test that can very accurately detect its presence. It's time to put this knowledge into practice so that women can benefit from these discoveries.
"The recent decision by the NHS screening programme to defer cervical screening until the age of 25 also makes HPV testing more attractive because there will be fewer false positives after this age."
Prof Peter Sasieni, of Cancer Research UK, who co-authored the report, says: "The recent decision by the NHS Screening Programme to introduce liquid based cytology in cervical screening will reduce the number of inadequate smear tests, but is unlikely to have a substantial impact on cervical cancer rates. HPV testing offers the best hope of improving the effectiveness of cervical screening.
"The HPV test can be performed on the same sample as is used for the smear test. So there is no need for women with HPV to come back for another test."
- The Lancet (2003) 362 pp. 1871-76
Notes to Editor:
All the women taking part in the study were over the age of 30 and nine per cent were found to carry HPV.
About 20 per cent of women under 25 carry the HPV virus but this drops to 5 per cent by the age of 40.
The study was carried out by recruiting women from 161 general practices associated with five referral centres in Birmingham, Edinburgh, London, Manchester and Mansfield.
The HPV test used in the study detects the DNA of 13 different HPV types that are known to be relevant to cervical cancer. The test is applied to the cells obtained from a routine cervical scrape (smear), but they are put into a liquid transport medium rather than being smeared onto a glass slide. Use of this medium has recently been recommended by the NICE committee even for cytology, making it very easy to do both tests from the same sample.
Unlike earlier HPV tests, this test - known as Hybrid Capture 2 - is suitable for large-scale use in hospital laboratories. The test is easily automated and gives an objective black and white result which, unlike the smear test, is not subject to human interpretation and possible error.