HPV genotype distribution according to severity of cervical neoplasia

To analyse the HPV genotype profile and the presence of multiple HPV infections according to severity of cervical intraepithelial neoplasia.

From a population of 424,143 women in Norway, we included all women (n=643) with histologically confirmed cervical intraepithelial neoplasia grade 2 or higher (CIN2+) and evaluable HPV test during 2005 and 2006. Histology revealed CIN2 in 135 women, CIN3/ACIS in 495, and invasive carcinoma in 13 women. HPV genotyping was performed on cell suspensions from cervix by linear array which differentiates 37 HPV genotypes.

HPV was detected in 98.4% (633/643) of the women, of whom 52.5% (338/643) were infected with more than one HPV genotype. HPV16 was most common, being detected in 51.2% (329/643) of all cases, followed by HPV31, 33, 52, 18, and 51. Overall, HPV 16 or 18 were detected in 58.0% (373/643), with 34.7% (223/643) without concurrence of other high-risk genotypes. HPV16 and HPV33 as single infections were more common in women with CIN3+ as compared to CIN2 (age-adjusted odds ratio=5.93, 95% CI=2.73-12.87, and age-adjusted odds ratio=4.53, 95% CI=1.42-14.46, respectively). Concurrent infection with other HPV genotypes did not significantly alter the associations to CIN3+ for HPV16 or HPV33. A single HPV infection, other than HPV16, 18, 31, or 33, was used as the reference. HPV18 or multiple HPV infections not including HPV16 or HPV33 were not associated with the severity of cervical neoplasia.

HPV16 and HPV33 appear to have a higher oncogenic potential than other HPV genotypes.