A number of recent studies have considered the case for HPV-related cancer prevention interventions that are targeted at specific populations. In the developed world, interventions of cervical screening and teenage vaccination aim to cover the female, or male and female, population (at a certain age) in order to prevent cervical cancer. The question of more targeted interventions generally arises in relation to MSM – and especially HIV+ MSM – on account of their heightened risk of HPV-induced anal cancers. There has been a marked rise in these cancers since the 1980s. Unlike cervical cancers in heterosexual women (which decline with age), anal cancers are prevalent in MSM of all ages (Poynton & Grulich (STI)) – possibly reflecting higher rates of exposure through new partners. Particularly high rates of anal cancer in older MSM living with HIV may be attributable to long-term immunologic defects in this population (van der Laar & Richel (STI)). Elevated HPV rates have also been shown in sexual minority women (Reiter & McRee (STI)). Of course, the problem of anal cancers in MSM could be resolved through vaccination of adolescent boys. However, a recent UK study has investigated the feasibility of delivering a targeted HPV vaccination programme to adult MSM through STI clinics (Bayley & Soldan (STI)).
In developing countries, there could also be a case for targeting HPV screening – but for the prevention of cervical cancer in heterosexual women, rather anal cancer amongst MSM. In most parts of sub-Saharan African, and other limited resource settings, neither cervical screening nor widespread adolescent vaccination have proved feasible, and rates of cervical cancer are relatively high (WJCO: Cervical Screening in Limited Resource Settings). Here, Whitham & Kulasingam (W&K) have argued in a recent analysis of the evidence from six longitudinal studies undertaken in Senegal from 1994-2010, that some targeting of the available resources towards women who are HIV+ is justified given their considerably elevated levels of risk. Like the HIV+ MSM in the studies mentioned above, HIV+ heterosexual women, according to W&K, have much higher rates of progression from HPV to high-grade squamous intraepithelial lesions (HSIL) (HR 2.55 times), as well as higher levels of progression from normal to HPV, and from normal to HSIL (respectively, HR 1.53 and 1.58). These rates corroborate the results of earlier studies (e.g. Mayaud & Lacey (STI)) that suggest high-risk HPV types and a tendency to HSIL in HIV+ in the older female population.
These findings prompt W&K to recommend, in the sub-Saharan setting, the policy of targeting of HPV vaccination to the HIV+ population recently proposed in the developed world for HIV+ MSM. Unfortunately, various problems make such an intervention considerably less feasible in the case of sub-Saharan HIV+ women. First, the sheer prevalence of HPV amongst the target population make HPV testing inefficient as a stand-alone screening strategy and tends to reduce its positive predictive value. Second, the tests current in the West (cytology and Hybrid Capture 2) require laboratory equipment and technician expertise not likely to be available in Africa. On the latter point, however, W&K note that the recently developed careHPV test may offer a more effective alternative to Visual Inspection with Acetic acid (VIA).