By Helen Briggs
Health reporter, BBC News
Minor abnormalities in smear tests are very common
Testing for human papillomavirus during cervical screening does not help doctors identify women at risk of cancer, a study suggests.
A positive HPV test does not accurately predict which women need an urgent follow-up, say doctors.
Each year, millions of UK women have a cervical screening test as part of the national programme.
The NHS is piloting add-on tests for the virus linked to cervical cancer at several UK centres.
Other studies have shown this could be a useful tool for identifying women at high risk of developing cervical cancer.
Around six out of 100 women who have a test receive a borderline or mild abnormality result.
But only a tiny minority of these will go on to develop cervical cancer.
The study, funded by the Medical Research Council, looked at 4,439 women undergoing cervical screening in Grampian, Tayside and Nottingham.
Those with mild abnormalities were tested to see if they were positive for HPV, a sexually-transmitted infection linked to most cases of cervical cancer.
But the researchers found 70% of women testing positive for HPV after a mild abnormality result did not develop early signs of cancer during a three-year follow-up.
Around 2,800 women are diagnosed with it each year in the UK
May not cause any symptoms at all until it has reached an advanced stage
Abnormal bleeding is the most common symptom
Dr Maggie Cruickshank, from the Department of Obstetrics and Gynaecology at the University of Aberdeen, led the study.
She said: "The most important thing is to attend for cervical cancer screening - the most effective way of preventing cervical cancer.
"This new additional test may not add any value.
"Our study is showing that HPV is such a common infection in younger women that testing for it doesn't help decide which is the best action to take."
But in women over 40, HPV testing might be useful for ruling out further investigations, she added.
Professor Jack Cuzick is an epidemiologist for Cancer Research UK.
He said other studies have shown that HPV testing is good at detecting abnormalities in women with low-grade tests and can reduce the number who need to be referred for treatment, especially in the over 35s.
He added: "The results of this study are surprising, as they're very much out of line with most other studies in the field.
"One thing to note is that the type of test used isn't commercially available, so we need to be careful when considering these results in the context of our national screening programme."
Julietta Patnick, director of the NHS Cancer Screening Programmes, said the results of the study would be reviewed.
Full details of the research are published in the British Journal of Obstetrics and Gynaecology.