Factors that differentiate risk of cervical cancer associated with infection with single versus multiple HPV types are yet undefined. We hypothesize that E6 oncoprotein is one determining factor. This cross-sectional, multicenter study was performed between 2013 and 2017. A total of 1,781 women were recruited from six hospitals. Samples were tested for presence of 14 types of high-risk HPV DNA. HPV16/18-positive samples were also tested for HPV16/18-E6 oncoprotein. Of 1,781 subjects, 687 (38.6%) tested positive for HPV16/18. HPV16/18 single infections were associated with higher E6 positivity rates compared with multiple infections only for cancer cases (HPV16: 92.2% vs. 76.5%; HPV18: 93.9% vs. 62.1%) but not for normal histopathology or cervical intraepithelial neoplasia. In HPV16/18 coinfection subjects, the positivity rate was 42.9% for HPV16-E6 and 42.9% for HPV18-E6. The combined positivity rate of either HPV16-E6 or HPV18-E6 among HPV16/18 coinfection subjects was 78.6%, similar with HPV16 (74.8%) and HPV18 (79.5%) single-infection subjects. The positivity rates of HPV16/18 E6 oncoprotein varied depending on the HPV-type composition in multiple infection ("clusters") including HPV types other than 16 and 18. Multiple infection clusters most likely to express HPV16-E6 and HPV18-E6 were HPV16/52 (61.5%) and HPV18/52 (66.7%), and the less were HPV16/45 (10.0%) and HPV18/51 (16.7%), respectively. Patterns of E6 oncoprotein expression varied depending on clustering types. However, expression was greatest in women with single HPV-type infections compared with those with multiple HPV types regardless of histopathology. Our findings provided new insight of natural history of cervical cancer.
©2019 American Association for Cancer Research.