Confirming the benefits of cervical screening and HPV vaccination

The study by the Australian Institute of Health and Welfare (AIHW) is the third in a series.

‘This is another report from the AIHW from the major data-linkage project undertaken between the cancer screening program, the cancer registry, HPV [human papillomavirus] vaccination and death data,’ Associate Professor Julia Brotherton, public health physician at the Victorian Cytology Service Foundation who assisted with the clinical interpretation of the data, told newsGP.
 
‘These data highlight the power of linking datasets together to get a better picture of the impact of our prevention programs.’

The report analyses data relating to diagnoses of cervical cancers in women aged 20–69 in the years 2002–12, categorised by their screen detection status and screening history.
 
It shows that screening, which is designed to detect precancerous abnormalities before they progress to cervical cancer, often has the intended preventive effect, with most cervical cancers – more than 70% – occurring in women who were either never screened or who had lapsed in screening.
 
For those with screening-detected cervical cancers (in 5% of the cohort studied), they were 77% less likely to cause death than those found in women who had never screened.

‘This is likely due to down-staging and because screen-detectable cancers are more likely to be of epithelial origin,’ Associate Professor Brotherton explained.
 
There were also significant findings in relation to vaccination for human papillomavirus (HPV). Women who were vaccinated had a lower incidence of high-grade abnormalities detected in screening than women who were not, at rates of nine per 1000 women compared to 13 per 1000, respectively.
 
The difference became even more pronounced when looking at precancerous abnormalities only, cervical intraepithelial neoplasia (CIN) grade 3 and adenocarcinoma in situ (AIS), with HPV-vaccinated women showing incidence at a rate of three cases per 1000, compared to six cases per 1000 for unvaccinated women.

‘The data provides confirmation at a national level of the impact of HPV vaccine on prevention of high-grade lesions, with fully vaccinated women having a 57% lower risk of CIN3/AIS,’ Associate Professor Brotherton said.
 
Despite the greater protection it affords, HPV-vaccinated women were more likely to participate in cervical screening, with participation rising with increasing numbers of vaccine doses received for both relevant age groups of 20–24 years and 25–29 years.
 
There has not yet been sufficient time since HPV vaccination was introduced to determine its effects on overall incidence of cervical cancer, but the report concludes that participation in the screening program is beneficial to women due to early detection of precancerous changes and of cervical cancer itself.
 
Associate Professor Brotherton is pleased with the report’s results, and urges GPs to continue in their efforts to promote cervical screening and HPV vaccination throughout Australia, with the ultimate goal of potentially eliminating this cancer altogether.
 
‘Participating in screening saves lives and it is now easier than ever for women with a five-year screening interval and the option of self-collection for women 30 and over who refuse a speculum and are four years or more since their last Pap test,’ she said.
 
‘Screening and vaccination are working together to reduce our cervical cancer burden. Our challenge is to encourage all women from all backgrounds to participate so that no one is left behind in our push to make cervical cancer a rare disease.
 
‘It’s important to think about who in your practice is neither vaccinated nor screened and have a conversation with them about what they can do to reduce their risk of cervical cancer. A face-to-face discussion with a supportive GP can make all the difference in taking the next step.’

cervical cancer HPV screening women’s health week