Smear tests designed to cut deaths from cervical cancer could be improved by adding a further test looking for signs of a virus which causes it. When smears from thousands of Dutch women were also checked for the human papillomavirus (HPV) doctors were able to find more cancers at an early stage. The authors of the Lancet Oncology study are now calling for the test to be included for all women. Experts said the findings were encouraging. The UK currently invites women aged between 25 and 65 for smear tests every three to five years. The test is based on "cytology" - a sample of cells from the neck of the womb is examined under the microscope for subtle changes which may lead to cancer. HPV, a sexually-transmitted virus, is now known to cause the vast majority of cervical cancers in the developed world. More work needed In the UK, many teenage girls are now vaccinated against the strains most strongly linked to the disease. However, this leaves the majority of adult women unprotected from the virus, and HPV testing during screening has been suggested as a way of detecting those most at risk. HPV testing was introduced earlier this year in the UK for women who have "borderline" results under the microscope to avoid the need for extra, invasive checks. However, the Dutch study examined the principle of checking every sample, with those testing positive for high-risk strains invited for additional smear tests. Analysis of the 45,000 women in the study suggested this tactic prevented an additional 10 cancers per 100,000 women screened compared with conventional screening, and revealed a higher number of pre-cancerous growths which could be treated. The researchers said their findings suggested that HPV testing should be introduced in cervical screening programmes for women aged 30 and above. If it were, in theory the need for three-yearly smears in some women might be reduced, they concluded, with a five-year interval equally safe. This was supported by US cancer specialists who reviewed the results for the journal. They wrote: "We expect that almost every women who tests negative for HPV, irrespective of country or screening protocol, has an extremely low risk of cancer over three or five years. Jessica Harris, from Cancer Research UK, said: "These results add to previous evidence showing that HPV testing is an effective way of picking up pre-cancerous cervical changes in women over 30. "But it's important to answer some outstanding questions about how HPV screening could work in the real world, including how best to manage women who receive a positive HPV test result, and what to do for younger women." Professor Julietta Patnick, director of the NHS Cancer Screening Programme, said the results suggested that more work should be undertaken to examine the role of HPV testing in the UK. She said: "The relationship between HPV and cervical cancer is well established and we are beginning to incorporate testing for it into our current cytology based Programme. This study shows that HPV testing potentially offers greater benefits for women than cytology alone."