Abstract PR06: Racial/ethnic variation in the prevalence of vaccine-preventable human papillomavirus genotypes

Abstract

Abstract Introduction: The bi- and quadrivalent human papillomavirus (HPV) vaccines that have been on the market for ≥ 9 years protect against high-risk HPV types 16 and 18, the two HPV genotypes causally associated with ≥ 70% of cervical cancers. The recent nonavalent vaccine, which became commercially available in 2014, additionally protects against high-risk types 31, 33, 45, 52, and 58. The quadri- and nonavalent vaccines also protect against low-risk HPV types 6 and 11, which cause genital warts. The objective of this analysis is to compare the prevalence of vaccine-preventable HPV genotypes among non-Hispanic white, non-Hispanic black, Hispanic, and Asian women and determine the risk of cervical dysplasia (CIN2+) associated with the genotypes covered by each of the vaccines. Methods: Patients in this analysis represent a subset of those participating in a clinical trial to evaluate new optical technologies for the diagnosis of cervical dysplasia. Trial participants were non-pregnant women, age ≥18 years, with a recent abnormal Pap test and were recruited at participating colposcopy clinics in Houston, El Paso, and Vancouver. As part of the parent trial, a subset of participants provided a biopsy and a cervical swab. Histologic diagnosis was based on biopsies and evaluated by a certified pathologist to represent the histology of the most severe biopsy. HPV genotyping was conducted using the Roche Linear Array. Prevalent HPV types were grouped according to their inclusion in each of the vaccines: bivalent (16, 18), quadrivalent (16, 18, 6, 11), and nonavalent (16, 18, 31, 33, 45, 52, 58, 6, 11). Women were considered to be potentially protected by a particular vaccine if all or some (in the case of multiple infections) type-specific infections were covered by the vaccine. Results for the bi- and quadrivalent vaccines were grouped given the small number of women additionally protected by the quadri- versus bivalent vaccine. Results: The sample for this analysis (n= 419) is comprised of 206 non-Hispanic white, 39 non-Hispanic Black, 142 Hispanic, and 32 Asian women. The prevalence of HPV genotypes covered by the bi- and quadrivalent vaccines was significantly greater among non-Hispanic white (38.3%) and Asian women (37.5%) compared to non-Hispanic black (15.4%) and Hispanic women (19.7%). The increase in the proportion of women potentially protected by the nonavalent vaccine versus the bi-/quadrivalent vaccine was highest among non-Hispanic blacks (33.3% increase) followed by Hispanics (18.3% increase). However, the prevalence of HPV genotypes not covered by any vaccine was also highest among these racial/ethnic groups. Specifically, 42.3% and 35.9% of Hispanic and non-Hispanic black women, respectively, had ≥ 1 genotype not covered by any vaccine, compared to 24.3% and 15.6% among non-Hispanic white and Asian women, respectively. Non-vaccine HPV types were primarily high-risk (68%). Among women with a CIN2+ diagnosis, 37.3% had genotypes included in the bi/quadrivalent vaccine and an additional 46.7% had genotypes included in the nonavalent (but not the bi/quadrivalent) vaccine. However, 16.0% of CIN2+ diagnoses occurred among women with HPV genotypes not covered by any vaccine. Conclusions: Our data suggest racial/ethnic differences in the proportion of women protected by the new nonavalent HPV vaccine. In particular, non-Hispanic black and Hispanic women had the greatest prevalence of HPV types covered by the nonavalent but not the bi-/quadrivalent vaccines. Nonetheless, a large proportion of women from these racial/ethnic groups were infected with genotypes not covered by any vaccine. While HPV 16 and 18 are known to cause most cervical cancers, non-vaccine genotypes were associated with 16% of CIN2+ histology, a diagnosis often requiring significant therapeutic intervention. This abstract is also presented as Poster C38. Citation Format: Indu Varier, Jane R. Montealegre, Christina M. Gutierrez, Laura M. Dillon, Martial Guillaud, Karen A. Storthz, Michele Follen, Andrew G. Sikora, Michael E. Scheurer. Racial/ethnic variation in the prevalence of vaccine-preventable human papillomavirus genotypes. [abstract]. In: Proceedings of the Eighth AACR Conference on The Science of Health Disparities in Racial/Ethnic Minorities and the Medically Underserved; Nov 13-16, 2015; Atlanta, GA. Philadelphia (PA): AACR; Cancer Epidemiol Biomarkers Prev 2016;25(3 Suppl):Abstract nr PR06.