DNA screening for the virus that causes cervical cancer is more effective than Pap-smear-like methods for detecting pre-cancerous cells, even in women vaccinated against the virus, Australian researchers have found.

Key points: First time effectiveness of HPV screening tested in women immunised against strains of virus that cause cervical cancer

First time effectiveness of HPV screening tested in women immunised against strains of virus that cause cervical cancer Study compared effectiveness of HPV DNA screening every 5 years versus cell-based screening techniques every 2.5 years

Study compared effectiveness of HPV DNA screening every 5 years versus cell-based screening techniques every 2.5 years Scientists say findings indicate upcoming changes to cervical screening program "safe and appropriate"

They said the study, published today in the journal PLOS Medicine, supports changes to the cervical cancer screening program, which are due to be implemented on December 1.

Primary HPV screening looks for DNA from the human papillomavirus virus strains that cause the vast majority of cervical cancers.

It differs from other methods, such as Pap smears and liquid-based cytology screening, which look for changes to the cervical cells themselves — although the same procedure for taking a Pap smear is used to collect the HPV sample.

Karen Canfell, director of the Cancer Research Division at the Cancer Council NSW, said HPV screening for cervical cancer had been extensively studied and modelled, and shown to be better than Pap smears and liquid-based cytology.

But Professor Canfell said this was the first time the technique had been tested in a population where the HPV vaccine had been available.

"We're always building the evidence base," Professor Canfell said.

"This is just yet another plank supporting the move to primary HPV screening, which is essentially a more sensitive measure of assessing a woman's risk of cervical cancer."

The researchers studied data from nearly 5,000 women in Victoria aged between 25 and 65, some of whom were vaccinated against HPV and some who weren't.

The women were screened, either using liquid-based cytology alone every 2.5 years, HPV testing followed by liquid-based cytology in women who tested positive for high-risk viral subtypes, or HPV testing with another type of cell analysis in the high-risk subtype women every five years.

The study found up to 10 times more high-risk cervical abnormalities were picked up in the women screened using the HPV testing, compared to those screened using the liquid-based cytology alone.

Immunisation a game changer for cervical screening

In December, the national cervical screening program will move from two-yearly Pap tests to five-yearly HPV screening from age 25.

"Australia has led the world as the first country to implement a national, publicly funded HPV vaccination program so that's why we're seeing the implications for cervical screening play out perhaps sooner than in other countries," Professor Canfell said.

"HPV immunisation has been a complete game changer for cervical screening."

Professor Suzanne Garland, director of the Women's Centre for Infectious Diseases at the Royal Women's Hospital, Melbourne, said the trial effectively mimicked the renewed cervical cancer screening program to be implemented at the end of this year, and was "great news".

"The results from this recent, randomised, controlled trial in Australia, conducted after vaccination has been implemented now for 10 years, gives us confidence that the decision being made to move to HPV DNA testing … is a safe and appropriate change," said Professor Garland, who was also on the scientific advisory committee for the study.

The research team is now working to recruit 121,000 Australian women in South Australia and Victoria for what will be Australia's largest clinical trial.

It will compare Pap-smear-based screening with HPV testing in a younger group of women who have been offered HPV vaccination as part of the national immunisation schedule, to look more closely at the effect of vaccination on different screening methods.