HPV vaccination in boys should not be discounted
A partir de 16 modèles mathématiques identifiés à l'aide d'une revue systématique de la littérature publiée entre 2009 et 2015 (51 articles), cette méta-analyse estime, en fonction du taux de couverture vaccinale contre quatre types de papillomavirus humains (16, 18, 6 et 11) chez les filles et les garçons âgés de 12 ans, la réduction relative de la prévalence des infections par ces virus, soixante-dix ans après la mise en place du programme de vaccination
In The Lancet Public Health, Marc Brisson and colleagues report pooled results from multiple mathematical models to predict the effect of human papillomavirus (HPV) vaccination on HPV infections. A unified input dataset was used to obtain results from 16 models that were combined using meta-analysis, yielding interesting findings about the dynamics of vaccination in girls and boys. Models such as those included in this study have become increasingly important to inform policy makers about predicted effects of interventions as well as other endpoints, such as cost, and the authors should be commended for their approach.
One major finding of this paper is that a high rate of HPV vaccination in girls confers adequate protection of boys through herd immunity. For example, for men, predicted overall prevalence of HPV 16 decreased by 36% (80% uncertainty interval 28–61) after 70 years of girls-only vaccination assuming 40% coverage, and by 83% (75–100) assuming 80% coverage. Notably, elimination of viral prevalence in boys, especially for HPV 16, was not achieved with this girls-only strategy. In view of the substantial herd effects of girls-only vaccination when coverage is moderate to high, the authors conclude that the incremental benefit of vaccinating boys is predicted to be small. Such conclusions could focus policy makers away from vaccination programmes targeting boys. However, HPV-related cancers have become an increasingly important issue for men in high-income countries.
HPV is thought to cause about 91% of anal cancers, 72% of oropharyngeal cancers, and 63% of penile cancers in the USA. The vast majority of HPV-related cancers in men are attributable to type 16.4, 5 Oropharyngeal cancers specifically have caused a substantial shift in the landscape of HPV-related cancers. Oropharyngeal carcinoma is approximately five times more common in middle-aged men than in middle-aged women.6 Incidence has been increasing at an alarming, even epidemic, rate, with an increase of 225% between 1988 and 2004 in the USA (from 0·8 cases per 100 000 people in 1988, to 2·6 cases per 100 000 people in 2004).3 Meanwhile, comprehensive screening programmes have been successful in decreasing the incidence of cervical cancer in high-income countries. In 2010, incidence of oropharyngeal cancer overtook that of cervical cancer in the USA. Furthermore, it is predicted that cases of HPV-related oropharyngeal cancer will surpass all cases of cervical cancer in 4 years, with more recent evidence suggesting that this might have already occurred in the USA.
Unfortunately, unlike with Pap and HPV testing of the cervix, no effective screening measures are available for oropharyngeal cancer. As such, patients often present with late-stage disease, requiring extensive multimodality treatment, which often results in long-term morbidity.7 Without any method of early detection of HPV-related oropharyngeal cancer in men, the importance of primary prevention through the vaccination of boys is further emphasised.
The cost of treating patients with oropharyngeal cancer has also been underestimated in the scientific literature. Costs for oropharyngeal cancers are often pooled with costs for oral cavity or salivary cancers, whose treatment and long-term outcomes, and hence costs, are on average much lower than that of oropharyngeal cancers.8, 9 Because most patients present with advanced disease, multimodality therapy is almost always required, substantially increasing health-care use and cost. Our group is currently investigating the cost of treating oropharyngeal cancer in Texas, USA, specifically omitting cancers of other head and neck sites. Our preliminary findings suggest that the true cost of oropharyngeal cancer treatment greatly exceeds the costs currently reported in the literature.
The Lancet Public Health , commentaire en libre accès, 2015