Background: Human papillomavirus (HPV) infection is the main cause of invasive cervical cancer, but cofactors may act in conjunction with HPV. We performed a pooled analysis of seven case-control studies to examine the effect of one possible HPV cofactor, herpes simplex virus-2 (HSV-2) infection, in the etiology of invasive cervical cancer.
Methods: Blood and exfoliated cervical specimens were obtained from 1263 case patients with invasive cervical cancer (1158 with squamous-cell carcinomas and 105 with adeno- or adenosquamous-cell carcinomas) and 1117 age-matched control subjects. Western blot analysis and/or an enzyme-linked immunosorbent assay were used to detect type-specific serum antibodies to HSV-2 and HSV-1, and Chlamydia trachomatis serum antibodies were detected using a micro-immunofluorescence assay. HPV DNA was detected using a polymerase chain reaction assay. Summary odds ratios (ORs) and 95% confidence intervals (CIs) were computed from unconditional logistic regression models.
Results: Overall, HSV-2 seropositivity was higher among case patients with squamous-cell carcinoma (44.4%, 95% CI = 41.5% to 47.3%) or adeno- or adenosquamous-cell carcinoma (43.8%, 95% CI = 34.2% to 53.5%) than among control subjects (25.6%, 95% CI = 23.0% to 28.2%). Cervical specimens from 1098 (94.8%) squamous-cell carcinoma case patients, 95 (90.5%) adeno- or adenosquamous carcinoma case patients, and 164 (14.7%) control subjects were positive for HPV DNA. Among the HPV DNA-positive women, HSV-2 seropositivity was associated with increased risks of squamous-cell carcinoma (OR = 2.19, 95% CI = 1.41 to 3.40) and adeno- or adenosquamous-cell carcinoma (OR = 3.37, 95% CI = 1.47 to 7.74) after adjustment for potential confounders. A similar association between HSV-2 seropositivity and squamous-cell carcinoma risk was observed after further controlling for markers of sexual behavior (OR = 1.96, 95% CI = 1.24 to 3.09). Among control subjects, HSV-2 seropositivity was associated with markers of sexual behavior, but not with cervical HPV DNA positivity.
Conclusion: HSV-2 infection may act in conjunction with HPV infection to increase the risk of invasive cervical carcinoma.