Abstract PL05-04: Introducing HPV screening into low-resource settings: Opportunities and challenges.

Abstract

Abstract Despite the promise of a highly efficacious prophylactic human papillomavirus (HPV) vaccination, screening and treatment of precancerous lesions will be needed for generations to come. In its current form, HPV vaccination will not prevent approximately 30% of invasive cervical cancer, does not treat pre-existing infections and precancerous lesions, and remains expensive and not yet feasible for many countries. Even if vaccines were made widely available at a greatly reduced cost and widespread vaccination could be rapidly implemented globally, the benefits of HPV vaccination will not be realized in 30 years or more. With adequate screening and treatment, the vast majority of cervical cancer can be prevented during the typical 10-15 year precancerous period. Unfortunately, successful screening programs in low resource settings have been difficult to achieve because of insensitive screening tests, low population coverage, and inadequate follow-up of screen positives. Cervical screening for carcinogenic HPV infection is being considered for low income countries because HPV testing provides excellent risk stratification and is amenable to vaginal self-collection. Fortunately, tests are being developed for low-resource settings. The natural history of HPV and cervical cancer informs the relative advantage of HPV screening compared to other screening tests that aim to detect precancerous lesions. In most populations, the age-specific prevalence pattern of HPV infections observed in sexually active women resembles that of a typical sexually transmissible infection. Incidence and prevalence peak at young ages soon after the start of sexual activity, with a subsequent decline as women age because their infections clear and fewer incident infections are acquired. The high sensitivity of HPV testing suggests that one or two screens in a lifetime, starting around 30 years of age and ending by menopause, before invasive cervical cancer arises, would be sufficient to substantially reduce cervical cancer mortality. This superior performance was observed in a large community randomized trial from India where HPV screening reduced mortality in just 7 years. The high sensitivity of HPV testing means that most women (80%–90%) who test HPV negative will have reassurance for at least 10 years that they are at low risk of cervical cancer. Numerous studies have demonstrated the long-term negative predictive value of HPV testing. Even when an affordable HPV test is available for low resource settings, challenges remain for successful implementation of HPV screening. Although vaginal sampling allows increased population coverage, it has been associated with loss of sensitivity. Women who screen HPV-positive must be managed adequately and various approaches with unique limitations have been considered. Finally, not all populations experience the same epidemiologic HPV-age trends where prevalence declines in older women. Some population-based HPV studies conducted in Sub-Saharan Africa observed elevated HPV prevalence in older women. In addition, the relationship between HPV and cervical cancer is further complicated in some settings by HIV infection. Compared to HIV-negative women, HIV-positive women are at an increased risk of HPV infection. Once infected, they also have a greater risk of persistent infection and cervical precancer (even with access to HIV antiretroviral therapies). This talk will review HPV epidemiologic research pertaining to the incorporation of HPV testing into cervical cancer prevention initiatives for traditionally underserved communities and low-resource settings. Citation Format: Julia C. Gage. Introducing HPV screening into low-resource settings: Opportunities and challenges. [abstract]. In: Proceedings of the Fifth AACR Conference on the Science of Cancer Health Disparities in Racial/Ethnic Minorities and the Medically Underserved; 2012 Oct 27-30; San Diego, CA. Philadelphia (PA): AACR; Cancer Epidemiol Biomarkers Prev 2012;21(10 Suppl):Abstract nr PL05-04.