The potential impact of human papillomavirus vaccination in contemporary cytologically screened populations may be underestimated: an observational retrospective analysis of invasive cervical cancers.

The aim of this study was to determine the proportion of invasive cervical cancers attributable to human papillomavirus (HPV) types 16 and 18 in a contemporary, cytologically well-screened UK population. This was achieved in a retrospective observational analysis by HPV typing 453 archival invasive cervical cancers diagnosed between January 1, 2000 and September 1, 2006. Pathological material was collected from 9 hospitals across Wales (UK), and HPV typing and pathology review was conducted at a central laboratory. Genotyping for high-risk HPV DNA was performed by PCR-enzyme immunoassay using the GP5+/6+ primer set. DNA was successfully extracted from 297 cases. Two hundred and eighty cases were included in the final analysis. The proportion of cases which had only HPV 16 and/or 18 was 219 of 280 (78.2%, 95% CI = 73.0-82.7); the proportion of cases which had HPV 16 or 18 and another HPV type was 230 of 280 (82.1%, 95% CI = 77.2-86.2). The proportion of cervical cancers associated with infection with HPV types 16 and 18 has previously been estimated at around 70%. The appropriate figure for a cytologically well-screened UK population appears to be approximately 80%. Hence, the potential impact of the current vaccination programme may be underestimated.