Abstract 5733: HPV type and variant distribution in cervical cancer cases in three cancer registry regions of Tunisia

Abstract

Cervical cancer disproportionately affects women in developing countries. Cervical cancer is the second most common cancer among Tunisian women, and the cervical cancer incidence rates vary by region. Three Tunisian registries report ASRs of 7.1/105 in the central region, 6.1/105 in the north, and 2.7/105 in the south. High-risk HPV types have genetic variants that differ in both carcinogenic potential and geographic distribution, with aggressive cervical cancers more often reported amongst women infected with HPV16 non-European variants. The HPV type and variant distribution could be a factor in the differing rates between regions. To establish the distribution of HPV types and variants in a cross-sectional study, cervical cancer cases diagnosed in 2007-2008 were identified from the Institut Salah Azaiez in Tunis and from the Central Tunisian Cancer Registry (2002-2007) of the Hôpital Farhat Hached in Sousse. Formalin-fixed paraffin-embedded sections were obtained from case tissue samples for analysis of HPV type and variant using PCR assays. Clinical information was abstracted from the pathology reports and medical records. A geographic location for each case was ascertained using residential information included in medical records. Of the 142 samples collected, 73 cases were from governorates included in the northern registry, 56 from the central registry, and 13 from the southern registry. Preliminary results show 110 cases (77.5%) were infected with at least one HPV type. HPV16 and HPV18 were present in 88.7% and 7.5% of cases infected with a single HPV type, and in 91.8% and 5.9% of squamous cell carcinomas (SCC), respectively. Whereas, HPV18/45 were detected in 33% of adenocarcinomas but in only 7.1% of SCC (p=0.02). Three cases were infected with both HPV16 and HPV18. HPV types 35, 45, 58, 66 and 73 were also identified. All of the HPV18 and 54.7% of HPV16 positive cases were European variants. The distribution of European variants was: 67.9% in the northern, 62.1% in the central, and 66.7% in the southern. Cases infected with a non-European variant of HPV16 had an average age at diagnosis of 53 years, while European infections were later at 55.9 years; although this difference was not significant. There was no difference in distribution of variants by stage of disease. There was no difference in HPV16 variant distribution by histologic type. This is the first study to evaluate HPV variants in Tunisia. Currently approved HPV vaccines will protect against the HPV types most commonly associated with cervical cancer in Tunisia. Although Tunisia is in Africa, frequent infection with European HPV variants most likely reflects the history of European migration both to and from Tunisia. Behavioral and cultural attitudes about screening and age-specific infection rates should be investigated to aid the development of any future vaccination and HPV screening policies. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 101st Annual Meeting of the American Association for Cancer Research; 2010 Apr 17-21; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2010;70(8 Suppl):Abstract nr 5733.