Substantial benefits of HPV screening plus vaccination ‘age dependent’
MedWire News: Human papillomavirus (HPV) vaccination combined with screening substantially reduces the incidence of pre-cancerous cervical changes, report researchers who have defined the optimal age for vaccination to take place.
Screening has successfully reduced the incidence of cervical cancer, addressing the up-to 68% 5-year mortality rate associated with the disease.
A recently developed vaccine against cervical cancer has been shown to provide up to 100% immunity against persistent HPV infection by the most common forms of the virus in women aged 15-25 years.
However, efficacy data are based on relatively short follow-up, leaving the long-term impact of vaccination on morbidity and mortality in doubt.
Noting this, Bruno Detournay (CEMKA-EVAL, Bourg-la-Reine, France) and co-workers constructed a Markov model to simulate the effects of screening and 100% vaccination coverage on cervical cancer outcomes over almost a century.
Writing in the International Journal of Public Health, the authors report that vaccination plus screening would be expected to reduce the incidence of cervical cancer by 78% if vaccination was given at 11 years of age, and by 35% if vaccination was given at 55 years of age.
Further analysis showed that vaccination at age 11 years only reduced cervical cancer risk by the same degree as screening every 5 years. But again, the greatest benefit was observed when screening and vaccination were performed together, resulting in a 48-fold reduction in risk compared with no screening or vaccination.
The researchers also show that, considering a whole-life horizon (90-year), vaccination at 11-13 years of age would prevent more cases of cervical cancer, cervical neoplastic intraepithelial neoplastic lesions, and deaths from cervical cancer than vaccination at any older age.
However, considering a 20-30-year time horizon, vaccination had the greatest impact on incidence and outcomes when given to girls aged 15-17 years compared with vaccination in any other age group.
Concluding, the authors say that, although their study helps to identify the factors to be considered when deciding on vaccination strategies such as coverage rate and age at vaccination, the optimal strategy is likely to vary between countries and by national public health policy.
MedWire (www.medwire-news.md) is an independent clinical news service provided by Springer Healthcare Limited. © Springer Healthcare Ltd; 2011
By Philip Ford