Should boys receive the human papillomavirus vaccine? NoBMJ 2009; 339 doi: https://doi.org/10.1136/bmj.b4921 (Published 07 December 2009) Cite this as: BMJ 2009;339:b4921
- Kate Cuschieri, principal clinical scientist
The burden of human papillomavirus (HPV) mediated disease is borne by women in the form of cervical cancer and its precursor lesions. Globally, cervical cancer is the second most common cancer in women, with an estimated 493 000 new cases and 274 000 deaths in 2002.1 It is a devastating cancer with a peak incidence in young women in their 30s. HPV vaccines and associated immunisation programmes are hugely expensive, and including boys will double the cost for a small unjustifiable return. All efforts and resources must be channelled into ensuring high coverage rates are achieved and sustained in girls.
Two HPV vaccines are currently available: a bivalent vaccine that protects against infection with HPV 16 and HPV 18 (the types responsible for about 70% of cervical cancer) and a quadrivalent vaccine that also protects against infection with HPV 6 and HPV 11 (which cause around 90% of genital warts). Data from clinical trials indicate that both are highly effective in preventing incident infection with vaccine type HPV and associated genital lesions. As a consequence, several countries have introduced HPV immunisation for young girls and women. However, even female only programmes are costly (estimated at £77m (€87m; $130m) a year in the UK), and some would consider them excessive in countries that have robust screening and low cancer rates (at least at the current vaccine price).2 Inclusion of males could be justified only if there were significant population benefits. This is not the case.
Some argue that immunising males will lead to enhanced herd immunity and consequently reduce rates of cervical cancer. However, the most consistent conclusion of the cost effectiveness evaluations is that vaccinating males provides only small additional benefit and is not cost effective,3 especially if female programmes obtain high (>75%) coverage. Such coverage rates are achievable—over 80% of adolescent girls have taken up the vaccine in national programmes in Australia and the UK.4 In resource poor settings, Kim et al (using Brazil as a model) concluded that at any coverage level, “A decision maker faced with the choice of trying to expand coverage in girls v boys should always increase coverage in girls first.”5
HPV is linked to other non-cervical neoplasms that affect men—namely, penile cancers, certain head and neck squamous cell cancers, and anal cancers. However, penile cancer accounts for <0.5% of male cancers worldwide and, unlike cervical cancer, has several independent causes, with HPV causing less than half of cases.6 As for head and neck cancers, the most potent risk factor is still smoking and alcohol consumption. The data on prevalence and attribution of HPV in head and neck cancers are conflicting, but a large study of 1670 cases found only 18% of oropharyngeal tumours were HPV associated.7 In addition, HPV associated head and neck cancers have a better prognosis than those that are HPV negative.8
Anal cancer is more similar to cervical cancer in that 90% of cases are attributable to HPV, but it is still comparatively rare. In the US, which has one of the highest rates, incidence is 0.9 cases per 100 000 population compared with eight cases of cervical cancer per 100 000 women.9 Moreover, an analysis of incidence in 19 countries showed that in most, anal cancer is twice as common in women than men.1 Men who have sex with men are at higher risk of anal cancer, but it would be more sensible to use targeted measures (such as anal screening) for this group than to try to vaccinate all boys. Furthermore, the effectiveness of the vaccine in reducing male neoplasms has not yet been proved in clinical trials.
Inequalities between the sexes regarding protection from genital warts apply only to countries that use the quadrivalent vaccine. Nevertheless, there have been understandable calls for genital warts to be factored into cost effectiveness analyses. Jit and colleagues’ economic evaluation that did incorporate the potential reduction of warts and non-cervical cancers still concluded that vaccinating boys was not cost effective.10 In the US, Hu and Goldie estimated the cost burden of non-cervical HPV associated disease to be 8%. This figure is not trivial, but does it warrant vaccinating both sexes when the other 92% is associated with the cervix?11 A more recent analysis would indicate not—Kim and Goldie concluded that the inclusion of boys in the US immunisation programme would exceed “conventional thresholds of good value for money.”12
Boys still benefit
To believe that by vaccinating girls, only girls will benefit is naive. Smith et al assessed the impact of the Australian programme (in which girls receive the quadrivalent vaccine) on overall HPV infection rates and predicted a reduction in the age standardised incidence of HPV 16 infections of 56% by 2010 and 92% by 2050.4 HPV 16 is the most commonly detected type in male (HPV associated) cancer.1 6 9 Other, recent Australian data have shown a reduction of genital warts in both vaccinated women and heterosexual men.13 It is inevitable that lower rates of circulating virus brought about by vaccinating females will lead to a reduction in HPV associated disease in men over time.
There is currently no robust evidence to justify the expense and effort of vaccinating boys with existing HPV vaccines either in developed or developing countries. To do so would constitute a misuse of resources and a diversion from what should be the primary objective— vaccinating as many young girls as possible.
Cite this as: BMJ 2009;339:b4921
Competing interests: KC has been a speaker for Merck and received research funding from GSK.