HPV type distribution in invasive cervical cancers in Italy: pooled analysis of three large studies

OBJECTIVE: The aim of this study is to describe the prevalence of HPV types in invasive cervical cancers in Italy from 1996 to 2008. METHODS: A pooled analysis of the three largest case series typed to date was performed. HPV typing was performed on paraffin-embedded slices. Molecular analyses were performed in four laboratories. Multivariate analyses were performed to test the associations between calendar time, age, and geographical area and the proportion of types 16/18. RESULTS: Out of 574 cancers, 24 (4.2%) were HPV negative. HPV 16 and 18 were responsible for 74.4% (378/508) and 80.3% (49/61) of the squamous cancers and adenocarcinomas, respectively. Other frequent types were 31 (9.5%), 45 (6.4%), and 58 (3.3%) for squamous cancers and 45 (13.3%), 31, 35, and 58 (5.0%) for adenocarcinomas. The proportion of HPV 16 and/or 18 decreased with age (p-value for trend <0.03), while it increased in cancers diagnosed in more recent years (p-value for trend < 0.005). CONCLUSIONS: The impact of HPV 16/18 vaccine on cervical cancer will be greater for early onset cancers. In vaccinated women, screening could be started at an older age without reducing protection.