New hope in cervical cancer battle
Sunday 3rd November 2013, 12:11AM GMT.
Screening for a virus provides up to 70% better protection against cervical cancer than conventional smear tests, a study has found.
Traditional tests involve examining cells under a microscope to detect changes that may indicate cancer.
The new approach includes an initial test for human papilloma virus (HPV), which can trigger the disease.
Research has now confirmed that primary screening for HPV significantly improves cancer detection rates.
Scientists led by Dr Guglielmo Ronco, from the Centre for Cancer Epidemiology and Prevention in Turin, Italy, analysed data from four major European trials in England, Italy, the Netherlands and Sweden comparing the two screening methods.
In total, 175,000 women aged 20 to 64 took part in the four trials, which lasted an average of 6.5 years.
Invasive cancer rates were similar for both groups during the first 2.5 years after the trials began. Thereafter, fewer cancers were detected in women who had undergone HPV screening.
The researchers calculated that overall, HPV screening protected 60% to 70% more women from invasive cervical cancer than conventional cytology-based screening alone.
Increased protection was especially notable in women aged 30 to 35 years, the scientists reported in The Lancet medical journal.
Dr Ronco said: “Until now, there have been no direct estimates of the relative efficacy of HPV-based versus cytology-based screening for prevention of invasive cancer in women who undergo regular screening, of how variables like age affect this efficacy, and of the duration of protection.
“Our analysis shows that HPV-based screening appears to prevent more invasive cervical cancers than does cytology, and on this basis, we recommend implementation of HPV-based cervical screening with triage from age 30 years at intervals of at least five years.”
Triage means that HPV-positive women have a follow-up conventional smear test. Only those with abnormal smear test results or persistent HPV infection are referred for a colposcopy, a close examination of the cervix using a magnifying instrument.
In a linked comment published in The Lancet, Sandra Isidean and Eduardo Franco, from McGill University in Canada, wrote: “The future of cervical cancer screening in high-resource settings will most probably incorporate primary HPV testing, a science-driven change in strategy that particularly befits the post-HPV vaccination era.”
The findings will be presented at the EUROGIN 2013 meeting taking place in Florence, Italy, next month.
Professor Julietta Patnick, director of NHS Cancer Screening Programmes, said: “These new results … are incredibly exciting.
“The relationship between human papilloma virus and cervical cancer has long been established, with the virus being found in over 99% of cervical cancer cases.
“The new study suggests that by using HPV for primary screening, we could protect 60-70% more women from cervical cancer than the current method.
“It also finds that by testing for HPV first we could test all women every five years. At the moment we test women aged 25-49 every three years.”
HPV primary screening was already being piloted at six English centres in Bristol, Liverpool, London, Manchester, Norwich and Sheffield, she said.
This year, the laboratories will screen around 150,000 women for HPV.
“The new pilot will help us to establish how we can put all of the right quality assurance systems in place to ensure we offer primary HPV screening to the population as safely and effectively as possible,” Prof Patnick added.