Distribution of Human Papillomavirus Types 16 and 18 Variants in Squamous Cell Carcinomas and Adenocarcinomas of the Cervix

The distributions of human papillomavirus (HPV) types detected in cervical adenocarcinomas and squamous cell tumors differ. However, whether the distributions of intratypic HPV variants seen in these two histological forms of cervical disease differ is unknown. Our objective was to compare the distribution of HPV intratypic variants observed in squamous cell carcinomas (SCC) and cervical tumors of glandular origin (e.g., adenocarcinomas; AC) for two HPV types commonly observed in cervical tumors, HPV16 and HPV18. Participants in a multicenter case-control study of AC and SCC conducted in the eastern United States were studied. A total of 85 HPV16 and/or HPV18 positive individuals (31 diagnosed with AC, 43 diagnosed with SCC, and 11 population controls) were included. For HPV16-positive individuals, both the noncoding long control region and the E6 open reading frame were sequenced, and classified into phylogenetic-based lineage groups (European, Asian-American, African1, and African2). For HPV18-positive individuals, the long control region region only was sequenced and classified into known intratypic lineages (European, Asian-Amerindian, and African). The distribution of these different intratypic lineages among AC cases, SCC cases, and population controls was compared using standard methods. Non-European HPV16 and/or HPV18 intratypic variants were observed in 42% of ACs compared with 16% of SCCs and 18% of population controls (P = 0.04). Intratypic variants from the Asian-American lineage of HPV16 accounted for the differences seen between histological groups. The differences observed between AC and SCC cases were strongest for HPV16, and persisted in analysis restricted to Caucasian women, suggesting that the effect cannot be explained by differences in the ethnic make-up of AC versus SCC cases. Cervical AC and SCC differ not only with respect to the distribution of HPV types detected but also with respect to intratypic variants observed. Non-European HPV16 and/or HPV18 variants are commonly seen in AC. A possible hormonal mechanism is suggested to explain the observed findings.