Abstract
A hospital-based case-control study was undertaken to examine the role of human papillomavirus (HPV) in the development of invasive cervical cancer in Brazil. The study included 199 histologically confirmed incident cases and 225 age-frequency-matched controls selected from a wide range of diagnostic categories. A polymerase chain reaction technique was used to detect HPV DNA in cervical specimens collected with spatula and brush. HPV DNA was detected in 84% of the 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. In addition to HPV, number of sexual partners, early age at first intercourse, parity and duration of oral contraceptive use were 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 (95% confidence interval 28.7-169.6) and with unidentified types was 12.0 (5.1-28.5). The very high risks found in this study further implicate this virus in the aetiology of cervical cancer.
Highlights
All odds ratios were adjusted for socioeconomic status as well as for age
Cervical specimens obtained by biopsy were available from 16 of the 29 cases whose smear was negative for human papillomavirus (HPV) DNA; in eight (50%) of them HPV DNA was detected
There was a decline in the percentage of controls with HPV DNA with increasing age, the trend was not statistically significant [X2 = 1.92, P = 0.17]
Summary
Between June 1990 and June 1991 women with a diagnosis of invasive cervical cancer and women selected as controls were recruited from seven hospitals in Sao Paulo City. Five of these are general hospitals, and two are hospitals for the treatment of cancer. For cases from the hospitals in which only cancer patients are treated (n = 48), controls were selected from the largest general hospital included in the study This was because had the cancer cases had another disease it is likely that they would have been treated there as it is the most commonly used referral hospital in the city. Evidence of a gynaecological or cytological abnormality detected on examination after recruitment was not a criterion for exclusion
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