Study examines risk of cervical treatment and associated outcomes under renewed screening program and in the context of HPV vaccination
A new study by Cancer Council NSW has found that HPV-based cervical screening in Australia is predicted to decrease a woman’s lifetime risk of cervical surgery, compared to the current Pap test program. As a consequence, the research also predicts a decrease in the number of pregnancy complications that can potentially arise from such surgery.
HPV screening – the system that Australia is transitioning to this December – enables earlier diagnosis of cervical lesions. It is expected to decrease cervical cancer rates and mortality by at least 20 per cent, and its impact on screening benefits has been widely demonstrated. However, its effect on the risk of cervical treatment hasn’t been looked at in detail so far.
Surgical treatment of high-grade abnormalities is one of the potential outcomes of screening – treating precancerous lesions avoids cancer developing down the track. In the large majority of women, treatment is necessary and there are no adverse effects. However, treatment can be unnecessary – in women under 25, it is estimated that up to 70 per cent of high-grade abnormalities (CIN 2/3) would regress on their own, without intervention. This is one of the reasons that the new cervical screening program involves starting screening women from their 25th birthday.
Previous research also showed that treatment of abnormalities detected during cervical screening might increase the risk of pregnancy complications later in life.
“The good news is that we have found that when the new cervical screening program comes into place, vaccinated women will be at a 13 per cent lower risk of cervical surgery over their lifetime compared to if Pap smear screening was maintained, and therefore they will also be less likely to have adverse pregnancy outcomes,” said Professor Karen Canfell, Director of Research at Cancer Council NSW.
“Specifically, we estimate that HPV screening will lead to up to 4-41 fewer preterm deliveries in 100,000 women, and up to 52 fewer low birthweight events per 100,000 women, compared to the existing Pap smear-based cervical screening program.”
“With the combined impact of HPV vaccination and the new cervical screening program, the rates of detected abnormalities, treatments, and the potential for associated pregnancy complications after cervical screening are expected to be much lower than before.
“This is another reassuring piece of research in the lead-up to the implementation of the renewed screening program – it gives us a glimpse into how well the integration of HPV vaccination and HPV screening is set to work here in Australia,” Prof Canfell concluded.
The findings come as thousands of women across Australia are hosting a Girls’ Night In. Girls’ Night In is a fantastic way to not only raise funds to support continued research into women’s cancers, but also to have conversations about ways to prevent cancer. Every Girls’ Night In will help raise much needed funds to help beat all women’s cancers.
Media contact: Isabelle Dubach, Cancer Council NSW, T: (02) 9334 1872 M: 0401 524 321, firstname.lastname@example.org
Notes to editor
- “How will transitioning from cytology to HPV testing change the balance between the benefits and harms of cervical cancer screening?” is a paper by Cancer Council NSW researchers, published in the International Journal of Cancer.
- It is the first study to predict the effects of HPV testing on both the benefits and harms of cervical screening.
- It’s also the first piece of research on the effect of HPV vaccination on the potential for adverse obstetric outcomes.
- The study grouped women according to their HPV vaccination status (unvaccinated; unvaccinated but offered vaccination as 12-13-year olds; and vaccinated).
- The study predicted the same effects across the three groups:
- The cumulative lifetime risk (CLR) of invasive cancer
- The cumulative lifetime risk (CLR) of surgical treatment
- Number of pre-term delivery events and low birthweight events
- The risks of cervical cancer diagnosis and death is predicted to decrease in all three groups under the renewed program, when compared to current practice – regardless of a woman’s vaccination status.
- The risk of lifetime exposure to cervical surgery under the renewed program is predicted to increase by 4% in unvaccinated women, stay the same in unvaccinated women offered vaccination, and decrease by 13% in vaccinated women.
- Around 87% of births in Australia are to mothers aged <36 years, and all Australian women in this age group have now been offered HPV vaccination.
- The Australian National Cervical Screening Program (NCSP) was established in 1991 and in December 2017 will transition from two-yearly cytology-based screening starting from age 18-20 to five-yearly HPV-based screening from age 25.