In Europe, 25 000 women die from cervical cancer every year. Most European countries have implemented programmes to vaccinate against the causal virus, the human papillomavirus (HPV), as well as Pap smear screening (cytology testing) to detect the early signs of cervical cancer. “However, vaccination and cytology testing are not enough. Vaccination and screening programmes need to improve further because no woman should die of cervical cancer,” says PreHdict’s project coordinator, Johannes Berkhof.
PreHdict collected extensive data on HPV-related disease, including incidences of HPV infections and disease, effectiveness of vaccination, performance of novel screening methods, screening practice, life style and demographics. The results were used to determine the prerequisites and strategies for effective HPV vaccination and testing in Europe, and to predict their likely impact on cervical screening programmes.
HPV-testing a priority for prevention
The early prevention of cervical cancer involves HPV vaccination, Papanicolaou (Pap) smear testing (cytology testing), and HPV screening. “Most countries in Europe have implemented HPV vaccination and Pap smear programmes, with varying degrees of success,” says Berkhof. The incidences of cervical cancer are therefore higher in some countries than in others. Many health care systems in Europe are also considering the implementation of HPV testing.
In the PreHdict project, medical researchers pooled clinical trial data across Europe. “This enabled us to demonstrate that HPV DNA testing is more sensitive than cytology testing (Pap smears). HPV-based screening provides up to 70% more protection against invasive cervical cancers compared with cytology screening,” reports Berkhof.
HPV vaccination helps prevent infection with the HPV types that cause most cervical cancers. Many countries have delivered HPV vaccination through a school-based programme. But even when girls have been vaccinated, it is still important for them to undergo screening at various intervals because the vaccination does not protect against all genotypes of HPV.
The Pap test screens for cervical intraepithelial neoplasia (CIN), which are abnormal cells that may develop into cancer. However, the Pap test is only 50-75% effective in detecting CIN Grade 2/3. “On its own, cytology testing for CIN is not optimal for screening women for the early signs of cervical cancer,” explains Berkhof. Simulation modelling by PreHdict researchers indicates that the addition of HPV testing to cervical cancer prevention programmes can reduce the incidence of cervical cancer by about 20%.
Room for improvement in screening programmes
As a result of the evidence-based data generated through PreHdict, several countries in Europe have integrated HPV testing into their cervical cancer prevention programmes. For example, Italy, the Netherlands and Sweden are currently implementing HPV-screening, as are the USA and Australia.
Health care systems can find it challenging to bolster vaccination and screening programmes. “Even if a health care system implements a vaccination programme, people can still refuse vaccination. For example, the uptake of HPV-vaccination is below 10% in Romania,” explains Berkhof.
Countries also need sufficient numbers of gynaecologists and laboratory technicians. And in addition to high-quality cytology and HPV-testing, as well as an infrastructure of laboratories and protocols, local organisations must proactively call women to attend testing at optimal intervals.
A willingness to be tested is also important, but some women are reluctant to undergo cervical smears. “Self-sampling is effective and can increase the screening uptake, but has not yet been implemented in Europe,” emphasises Berkhof.
PreHdict contributed to the body of evidence about optimal cervical cancer prevention and led to positive changes within some European countries. However, the battle against cervical cancer is far from over. The EU is continuing its fight against the disease by investing in a follow-on project, CoheaHr, which compares health service interventions to identify the most effective ways to further prevent HPV-related cancer.