UCSF

Background

New strategies are needed to combat the high incidence of cervical cancer in resource-limited settings such as sub-Saharan Africa. Screening for high-risk human papillomavirus (hrHPV) DNA is sensitive for pre-cancer, but its lack of specificity results in substantial overtreatment in low resource settings where additional testing (e.g., colposcopy) is rarely available. Testing for hrHPV E6/E7 mRNA may enhance specificity, but little is known about its performance characteristics in resource-limited settings.

Methods

In a series of community health fairs in rural Uganda, women aged 25 to 49 years provided self-collected vaginal samples, which were tested for hrHPV (types 16, 18, 31, 33, 35, 39, 45, 51, 52, 56, 58, 59, 66 and 68) E6/E7 mRNA with the Aptima® assay. Positive specimens underwent testing for HPV-16 and 18/45. After excluding pregnant women, all women testing positive for any hrHPV subsequently were offered cervical biopsy to determine pathology.

Results

A total of 1892 women provided a vaginal sample for hrHPV testing during 24 health fairs. The median age was 34 years, HIV prevalence was 10, and 95% had not been previously screened. Prevalence of any hrHPV E6/E7 mRNA was 21% (95% confidence interval (CI): 19 to 23%); the prevalence of HPV-16 was 2.6%, HPV-18/45 1.9%, and HPV 16 and 18/45 were jointly found in 0.1% of the study population. Younger age, pregnancy and HIV-positivity were independently associated with any hrHPV infection. Of the 255 evaluable cervical biopsies, the positive predictive value of detecting any hrHPV E6/E7 mRNA for presence of cervical intraepithelial neoplasia grade 2 or higher ("CIN 2+") was 8.2% (95% CI: 5.1 to 12%). The positive predictive value associated with detection of HPV-16 mRNA (15%) or HPV-18/45 mRNA (15%) was only slightly higher.

Conclusion

Among community-based women in Uganda, the prevalence of any hrHPV E6/E7 mRNA in vaginal samples was high, but the prevalence of the most oncogenic HPV types (16, 18, or 45) was substantially lower. Positive predictive value of hrHPV mRNA-positivity for CIN 2+ was also low, including when restricting to HPV 16/18/45-positivity. The findings emphasize the need to identify more specific screening approaches for cervical cancer.