Human papillomavirus genotypes in different histological types of cervical carcinoma
Background: Persistent infection with specific oncogenic types of human papilloma virus (HPV) has been strongly implicated in the aetiopathogenesis of cervical carcinoma by several epidemiological, clinical and molecular studies. Studies have also shown that differences exist in the prevalence and distribution of HPV genotypes among different histological types of cervical carcinoma. The objectives of this study were to determine the HPV prevalence and distribution of HPV genotypes in correlation with diverse histological subtypes of cervical cancer in Maiduguri, Nigeria.
Materials and Methods: This was a descriptive and retrospective study. Sixtythree archived paraffin-embedded tissue blocks and slides with confirmed diagnoses of cervical cancer during the study period (2013-2015) were retrieved. They were reviewed and classified according to World Health Organization (WHO) classification. The laboratory procedures included deparaffinization of tissue samples, DNA extraction, Polymerase Chain Reaction (PCR), gel electrophoresis and HPV genotyping by reverse hybridization line probe assay.
Results: Among the samples analysed, the proportion of squamous cell carcinoma was 84.1%, while adenocarcinoma and adenosquamous carcinoma accounted for 12.7% and 3.2% respectively. The overall prevalence of HPVspecific DNA in biopsies of cervical carcinoma was 69.8%. Multiple HPV types were found in 61.4% of the cases, while single HPV infection accounted for 38.6% of the total cases. The HPV-DNA positivity in squamous cell carcinoma, adenocarcinoma and adenosquamous carcinoma was 71.7%, 50.0% and 100% respectively. HPV18 was more predominantly associated with adenocarcinoma than with squamous cell carcinoma. Together, HPV16 and HPV18 accounted for 59.4% of HPV-positive cervical carcinomas.
Conclusion: HPV-DNA was found in majority of the examined cervical adenocarcinomas and adenosquamous carcinoma, similar to that of squamous cell carcinoma. Although the rare subtypes of adenocarcinoma were not associated with HPV infection, HPV-based tests and vaccines would significantly prevent cervical cancer.