17 October 2022
The World Health Organisation’s (WHO) global action plan for accelerating the elimination of cervical cancer aims to reduce the numbers diagnosed each year to 4 cases per 100,000 women by encouraging countries to implement a range of prevention strategies. It was adopted by the World Health Assembly in 2020. At this threshold the WHO will consider cervical cancer as eliminated. It is an ambitious goal. Prevention of cervical cancer hinges on a combination of vaccination against Human Papilloma Virus (HPV) and screening to identify and treat precancerous disease. Nevertheless, eliminating cervical cancer at all ages remains a distant prospect. Currently in England approximately 10 cases are diagnosed per 100,000 women each year (equivalent to ~2,600 cases) with most cervical cancers diagnosed in individuals under 50 years of age.
Vaccination against HPV has reduced rates of cervical cancer by 87%
In England, girls have been offered vaccination against the two most common cancer-causing HPV types (16 and 18) since 2008. The vaccine is targeted at girls aged between 12 and 13, however when vaccination was first introduced it was also offered to those aged 14 to 18. As these women enter their early twenties it has been possible to evaluate the early impact of vaccination. A recent study found that the HPV immunisation programme has almost eliminated cervical cancer in England among women born since September 1995. Compared with unvaccinated women, cervical cancer rates were 87% lower in women who had been offered the HPV vaccine at 12-13 years among whom the uptake was greatest and prior infection least likely, 62% lower in women targeted at 14-16 years old, and 34% lower in women targeted at 16-18 years old.
The impact of vaccination is likely to be even greater in the future because as of 2019 the offer of vaccination has been extended to boys aged between 12 and 13 and as of 2021 vaccination against nine cancer causing HPV types has been rolled out in England. As long as most people continue to accept vaccination against HPV, cervical cancer among women currently under age 30 is highly likely to be eliminated but it will take at least another 10 years for the full benefit to be realised.
Eliminating cervical cancer among older women requires a different strategy
Individuals born prior to 1990 have not benefited from vaccination against HPV. For these women screening is currently the only available prevention strategy. Cervical screening has been available in England to women aged 25 to 65 since 1988. Traditionally, screening involves sampling cells from the neck of the womb in search of abnormal changes (also called cytology), however in 2020 a new test which aims to detect the presence of the HPV virus (also called HPV primary screening) was rolled out in England. This new test is better at identifying women at risk of developing cervical cancer meaning more women can be treated before they develop cervical cancer. Modelling of cervical cancer rates to 2040 suggest that at current screening coverage (about 70% of eligible women attend as recommended) rates in women who have not benefited from vaccination will stagnate (above the elimination threshold) even after accounting for the increased performance of HPV primary testing. Hence in recent years research into innovative ways in which to deploy current tools has flourished.
Strategies being evaluated in a bid to optimise comprehensive cervical cancer prevention include:
- The option for women to take their own screening sample at home (also known as HPV self-sampling) to increase participation in screening and reduce inequalities in screening uptake. Self-sampling is already offered as an alternative to clinician taken samples in Australia and the Netherlands and is currently being evaluated for use in England.
- Offering vaccination against HPV to women aged up to 55 years who test negative to the virus.
- Development of therapeutic vaccines for HPV associated disease.
Will elimination of cervical cancer be equitable?
Successful elimination of cervical cancer first and foremost hinges on access to vaccination and screening services, which are often worse in areas where the risk of cervical cancer is highest. The willingness of healthy individuals to get vaccinated and participate in screening is influenced by community, cultural and economic factors. Research has shown that women in the most deprived groups are more likely to have HPV and of being diagnosed with cervical cancer, yet they are less likely to attend cervical screening. Further women from ethnic minority groups (particularly Indian and Bangladeshi women) are less likely to attend cervical screening compared to white British women. Health inequalities may be further exacerbated if individuals who are reluctant to receive vaccination are the same individuals reluctant to participate in screening. A better understanding of the barriers that prevent people from accessing preventative services and innovative prevention strategies that are proportionately targeted to those with highest unmet need would enable the elimination of cervical cancer more quickly.