A vaccine given to schoolgirls in Scotland to protect them from cervical pre-cancer has almost wiped out the disease, according to research involving the University of Strathclyde.
The study of the vaccine against human papillomavirus (HPV) has found a reduction of nearly 90% in the cancer-causing virus since the treatment was brought into Scottish schools a decade ago.
It discovered that, compared with unvaccinated women born in 1988, vaccinated women born in 1995 and 1996 showed an 89% reduction in the highest risk level of abnormal cells, known as CIN (cervical intraepithelial neoplasia) 3+. There were reductions of, respectively, 88% and 79% in the other risk levels of CIN 2+ and CIN grade 1.
Younger age at vaccination was associated with increasing vaccine effectiveness, at 86% for CIN 3+ or worse for women vaccinated at age 12-13, compared with 51% for women vaccinated at age 17. Unvaccinated women also showed a reduction in disease, suggesting that interruption of HPV transmission in Scotland has created substantial herd protection.
Cervical cancer is the second most common cancer in women aged under 35 in the UK and caused the deaths of more than 800 women in 2016. Infection with HPV types 16 and 18 is known to be the cause of at least 80 per cent of cases in Scotland. Recent population-based studies suggest that HPV also plays a part in causing other cancers, particularly head-and-neck, vulvo-vaginal and anal cancers.
Professor Chris Robertson and Dr Kimberley Kavanagh, both of the University of Strathclyde’s Department of Mathematics and Statistics, were the University’s lead researchers in the study, which has been published in the British Medical Journal.
Dr Kavanagh said: “The reductions in pre-cancer through this vaccination have been substantial. Finding, when we analysed the data, that the vaccine was protecting against an additional three types of HPV shows how effective it has been.
“We’re hoping to do follow-up research on people as they return to the cervical screening programme in future years. Cervical cancer is more likely to appear as women get older but this would help us to continue monitoring the impact of the vaccine.”
The research shows that routine vaccination of girls at age 12-13 with the HPV vaccine has led to a dramatic reduction in cervical pre-cancer and a near elimination of both low- and high- grade cervical disease in young Scottish women. The uptake of the vaccine in Scotland is about 90%.
The study assessed 140,000 women who received their first cervical screen between 2008 and 2016. It showed a reduction of up to 90% in cervical disease abnormalities – pre-cancerous cells.
The data are consistent with the reduced circulation of high-risk HPV infection in Scotland and confirm that the HPV vaccine should significantly reduce cervical cancer in the next few years; cervical cancer cases in women aged 20-24 have already reduced by 69% since 2012.
This study has been undertaken as part of the programme of surveillance of immunisation against human papillomavirus in Scotland. This research collaboration also involved the University of Edinburgh, Glasgow Caledonian University, the University of Aberdeen and three NHS Scotland organisations - Health Protection Scotland, the Information Services Division and the Scottish Human Papillomavirus Reference Laboratory.