Key considerations and current perspectives of epidemiological studies on human papillomavirus persistence, the intermediate phenotype to cervical cancer.

Persistent infection with human papillomavirus (HPV) causes essentially all precancerous cervical lesions and cervical cancer in females and thus is an important intermediate phenotype to cervical cancer. A majority of infected individuals naturally clear HPV viral infection, but the virus persists in a subset of infected hosts and the mechanism for this differential outcome is not well described. Most of the epidemiological studies have been cross-sectional in nature, and even with longitudinal studies, the definition of HPV persistence or clearance has not been well defined. There is no consensus on the correct time interval between HPV DNA tests, or how to utilize HPV persistence information in clinical management because there is no treatment for HPV. While most studies are performed with the endpoint of cancer, the intermediate phenotype has been overlooked. Epidemiological studies of HPV persistence suffer with several challenges in definitions, study designs, and analyses that undermine its importance in identifying and understanding the interactions between the viral and host genomes in the process of HPV infection pathogenesis. We have evaluated the current status of HPV persistence and provide perspectives on how the field would benefit from a research focus on intermediate phenotype in epidemiological studies.