Viral load of high-risk human papillomavirus in cervical squamous intraepithelial lesions

Objectives: This case-control study was conducted to investigate the role of viral load of high-risk human papillomaviruses (HPVs) in the development of cervical squamous intraepithelial lesions (SILs) and invasive cancers. Methods: A total of 30 female cases who had histological evidence of low-grade SIL ( n=10) or high-grade SIL and above ( n=20) were identified as the case group at the Tri-Service General Hospital, Taipei between September 1998 and March 1999. In addition, 80 female controls who had normal cervical cytology were enrolled and individually matched on age (±5 years) and date of recruitment to each case. Cervical swabs collected from study subjects were tested for the positivity and viral load of high-risk HPVs by Hybrid Capture II assay. Additionally, subjects completed a risk factor questionnaire. Results: Among sex behavioral factors studied, younger age at first intercourse was associated with a significantly elevated risk of cervical SIL and invasive cancers. With respect to HPV infection, high-risk HPV DNA was present in 70% (21/30) of case and 21% (17/80) of control subjects, resulting in an odds ratio (OR) of 6.6 [95% confidence interval (C.I.)=2.6–17.0]. Moreover, women who had a high viral load were at significantly greater risk for cervical SIL and invasive cancers than those who were infected with a low viral load (OR=18.0, 95% C.I.=3.0–108.5). Conclusions: Among the variables tested, infection with a high viral load of high-risk HPVs is the strongest determinant for cervical SIL and cervical cancers in Taiwan.