Human papillomavirus typing of invasive cervical cancers in Italy

Human papilloma viruses (HPV) are the necessary cause of invasive cervical cancer (ICC). Of the many different types identified so far, only a few of them account for the great majority of cases worldwide, with geographical differences in their distribution. Data on the local distribution are now of interest in view of the soon-to-come introduction of HPV type-specific prophylactic vaccines.

We have investigated HPV type distribution in samples of 48 ICC cases occurred in women living in North-East Italy in the years 1997-1999. Cases were extracted from the Venetian Tumour Registry files, as incident cases whose specimens had been processed in two Pathology Departments. Search and typing were performed by polymerase chain reaction (PCR) using GP5+/GP6+ primers, followed by direct sequencing or reverse dot blot. Three cases were PCR negative using the housekeeping primers and hence excluded. One case was negative by all HPV tests used. HPV 16 was present in 32 (72.7%) cases, as single infection in 28, in mixed infection in 4. Of the 44 positive cases, HPV 16 and HPV 18 accounted for 33 (75%), as single or mixed infections. The other high risk HPV types accounted for 11 (25%) of the remaining infections. Of the 32 HPV 16 positive cases, sequencing of the E6 gene could be performed in 25; the prototype isolate was identified in 7, and the variant T350G in 18; in 4 cases one or more additional mutations were present.

Our results suggest that HPV 16 has a very high prevalence among women with invasive cervical cancer in Italy; therefore, the use of a prophylactic vaccine for HPV types 16 and 18 could prevent up to 75% of invasive cervical cancers in Italy.