HPV type 18 is more oncopotent than HPV16 in uterine cervical carcinogenesis although HPV16 is the prevalent type in Chennai, India

Context: The highest incidence of uterine cervical cancer in India is reported in Chennai. The prevalence and oncopotency are to be considered for the development of vaccines and therapeutic agents.
Aims: The aim of the present study is to analyze the prevalence and oncopotency of high risk type HPV16 and 18 in cervical lesions.
Settings and Design: This study is designed with 130 study subjects for analysis of selected types of HPV 6/11 and 16/18, in four groups, in a course of three years. The Bethesda system of classification is followed for grouping the samples, using histopathologic examination in biopsies.
Materials and Methods: The biopsy samples were collected in 10% buffered formalin and were embedded in paraffin within 24 hours, for long-term preservation. The presence of HPV types were tested by PCR using type-specific primers for HPV16 and HPV18 in the DNA isolated from the subject′s biopsies. The stages of cervical lesions were identified by histopathology using the Hematoxylin Eosin stain.
Statistical Analysis Used: The data were subjected to statistical analysis, using the SPSS and INSTAT software packages for their associations and risk estimation, respectively. The Graph Pad Prism 2 x 2 contingency table was used for risk estimation and the Kruskel Wallis test was used for analysis of the associations.
Results: In the study population, the data indicated a high prevalence of HPV 16. However, during the course of study (1999 - 2003), four (66.6%) dysplasia cases with HPV 18, three (21.4%) dysplasia cases with HPV 16, and none with low-risk HPV6/11, turned into invasive cancer, within one year.
Conclusions: The observation of the study implied that HPV16 had a high prevalence in uterine cervical cancer compared with HPV18 cases. However, the development of invasive cancer from precancerous lesions was more for HPV18 infected cases than for HPV16 during the study period, which indicated the higher oncopotency of HPV type 18.

Keywords
HPV prevalence and risk, HPV 18-potent type, invasive cancer, PCR, uterine cervical lesions