A free quadravalent HPV vaccination program for young women commenced in 2008, publically funded vaccinations are registered in the NZ vaccination registry. Current recommendations for cervical screening include cervical cytology tests every 3 years for all women over the age of 20. Subsequently we have seen a modest reduction of high grade abnormalities in young vaccine eligible women. However as vaccination protects against only 2 oncogenic HPV types, has this resulted in a change in type distribution of HPV among women with high grade abnormalities? If this is so what if any are the clinical implications of this change?
To explore this question we will present data from 2 studies. The first is a matching of data from the NZ vaccination register and the National Cervical screening register. The second is a large multicenter study of over 600 women under the age of 25 undergoing observational management in young women with CIN2 ref 1.
In New Zealand approximately 60% of women aged between 20 and 25 have received at least 2 doses of Gardasil ©. Annually in NZ approximately 53,000 cytology samples are taken in women under the age of 25, 16% of which are reported as abnormal. Approximately 1000 high grade biopsies were reported in women under the age of 25 annually. By matching data from these registries we are able to determine that women who were vaccinated had a lower rate of high grade histological abnormalities and there was an overall trend to a lowering rate of high grade histology.
In the population of young women with high grade histological abnormalities women taking part in our observational study the proportion of women with HPV 16/18 related lesions has fallen from 40-12%. This fall has been most marked in non vaccinated women.
While HPV vaccination has resulted in only a modest decrease in high grade cytological abnormalities in young women there is evidence to suggest there has been a rapid decrease in the proportion of these abnormalities caused by HPV 16 and 18. There is evidence to suggest that non 16/18 lesions have a more benign course. We suggest therefore this has implications for screening and the treatment of high grade abnormalities in young women.
1 Sykes P, Innes C, Harker D, Whitehead M, van der Griend R, Lawton B, Hibma M, Fitzgerald P, Dudley N, Petrich S, Faherty J, Bergzoll C, Eva L, Parker C, Sadler L, Simcock B. Observational management of CIN2 in young women: A prospective multicentre trial. J Low Genit Tract Dis 2016; 20: 343-347.