Type-specific human papillomavirus distribution in invasive cervical carcinomas in Paraguay. A study of 432 cases

Cervical carcinoma is the most common malignant tumor among woman in Paraguay. Cytological screening programs have not been successful and a plan for human papillomavirus (HPV) based-screening program and/or vaccination is under evaluation. This study aimed to identify the contribution of HPV genotypes in invasive cervical cancer in Paraguay to provide essential background data to guide and assess the introduction and impact of new preventive strategies based on HPV. Four hundred thirty two histologically confirmed cases (1960-2004) were analyzed. HPV detection in paraffin blocks was performed at the Catalan Institute of Oncology using PCR with SPF-10 broad spectrum primers followed by DNA enzyme immunoassay and genotyping with a reverse hybridization line probe analysis. The majority of cases were squamous cell carcinoma (92.8%). Mean patients age was 48 years old. HPV DNA was detected in 73.1% of the cases and single infections were predominant (97.8%). The most common HPV single types were 16, 18, 45, 33, 31, 52, 35, and 39. 73.1% of HPV positive cases had an HPV 16, 18 as single infection. HPV16 was frequent in SCC whereas HPV 18 and 45 were prevalent in glandular tumors. Significant decrease of HPV 16 with age groups (P-trend = 0.022) and increase in other HPV types (P-trend > 0.001) were observed. The potential impact of HPV 16 and 18 for a vaccination program was 73.1%. The study provide a profile of the HPV situation in the country, with robust clinical, pathological and virological data which would permit a better cervical cancer screening and vaccination programs.