Human papillomaviruses and cervical cancer in Bangkok. I. Risk factors for invasive cervical carcinomas with human papillomavirus types 16 and 18 DNA

Personal interviews, tests for antibodies to herpes simplex virus type 2, Treponema pallidum, and hepatitis B, tests for hepatitis B surface antigen (HBsAg), and polymerase chain reaction-based assays for human papillomavirus (HPV) DNA in cervical scrapings were obtained from 190 women with squamous cell and 42 women with adenomatous cervical carcinoma and from 291 hospitalized controls diagnosed in Bangkok, Thailand, between September 1991 and September 1993. Risk was strongly associated with oncogenic HPV types, with types 16 and 18 predominating in squamous and adenomatous lesions, respectively. The 126 cases with HPV-16 and the 42 cases with HPV-18 were compared with 250 controls with no evidence of any HPV. The risk of both viral tumor types increased with decreasing age at first intercourse in this predominantly monogamous population, which may be explained by more visits to prostitutes by the husbands of cases with early than late age at first intercourse. HPV-16 tumors were weakly associated with HBsAg carrier state and smoking. The risk of tumors of both viral types increased with parity and use of oral contraceptives but not with injectable progestogens. Factors that may predispose to persistent, oncogenic HPV-16 or -18 infection may include estrogens or progestins in the presence of estrogens, immunosuppression, and smoking, but other factors related to low socioeconomic status are also involved.