Human papillomavirus and invasive cervical cancer in Brazil.

67 different types of human papillomavirus (HPV) have been described, and 28 have been isolated from benign and malignant genital lesions. Good experimental data have been produced to support an etiological role for HPV in the pathogenesis of anogenital cancer, especially cervical cancer which is the leading cancer in developing countries. Sao Paolo, Brazil, has one of the highest incidence rates for invasive cervical cancer worldwide. The authors therefore applied a hospital-based case-control study approach to examine the role of HPV in the development of the disease in Brazil. The study included 199 histologically confirmed incident cases and 225 age-frequency-matched controls selected from a wide range of diagnostic categories. HPV DNA was found in cervical specimens via a polymerase chain reaction technique in 84% of cases compared with 17% of controls. Grouping HPV types 16, 18, 31, and 33, 66% of the cases were positive compared with only 6% of the controls. Number of sex partners, early age at first intercourse, parity, and duration of oral contraceptive use were also significantly associated with an increased risk of cervical cancer. A history of previous Papanicolaou smears was significantly associated with a decreased risk. After adjustment, only presence of HPV DNA, parity, and history of previous smears remained as independent risk factors. The adjusted odds ratios of cervical cancer associated with HPV 16, 18, 31, and 33 was 69.7 with a 95% confidence interval of 28.7-169.6