Epidemiological aspects of human papillomavirus infection and cervical cancer in Brazil

OBJECTIVES: A study was conducted to determine the prevalence of HPV infection in cervical lesions of Brazilian women and to search for specific risk factors associated to progression to malignancy. METHODS: Five hundred and fourteen paraffin-embedded biopsies obtained from female cervical lesions were classified according to the Bethesda System in low grade squamous intraepithelial lesion (LSIL), high grade SIL (HSIL) and squamous cell carcinoma (SCC). Specimens were tested for the presence of human papillomavirus (HPV) types 6/11,16/18 and 31/33/35 DNA using non-isotopic in situ hybridization. RESULTS: HPV prevalence ranged from 85.6% in LSIL to 55.2% in SCC. Patients were analysed through an 8 year period: 27. 1% of the lesions spontaneously regressed while 43.6% persisted and 29.3% progressed to carcinoma. High risk types were present in 80.5% (Crude OR 13.8, P=0.0003) of the progressive lesions. Possible co-factors have also been evaluated: history of other sexually transmitted diseases, mainly syphilis, showed to be positively related to progression (Adjusted OR 13.0, P=0.0003) while oral contraceptive use and tobacco smoking were not significantly related to it (P>O.1). Association of two or more co-factors also proved to be related to progression. CONCLUSIONS: Oncogenic HPV types 16 and 18 and history of other concurrent sexually transmitted diseases were found to be significantly associated with progression to cancer. Smoking and the use of oral contraceptives did not show a relation to cancer establishment, but when they were associated a significant co-operative role in progression was demonstrated. Our study indicated that HPV and other risk factors for cancer can act together, corroborating the observation of a poor prognosis for Brazilian women presenting SILs.