HPV genotypes in CIN 2-3 lesions and cervical cancer: a population-based study

The distribution of human papillomavirus (HPV) varies between countries and continents leading to different effectiveness of upcoming prophylactic HPV vaccines. This study analyses the HPV distribution in CIN 2-3, recurrent CIN 2-3 and cervical cancer in Iceland. About 80% of incident cases with CIN 2-3 lesions in 1990 and 1999, 99% of cancer cases in 1990-1994 and 1999-2003, and cases with recurrent CIN 2-3 after conization in 1990 were tested with PCR analysis for the presence of 12 oncogenic HPV types. About 95% of the CIN 2-3 and 92% of the cancer cases tested positive for the included HPV types. HPV 16 was the most frequent type followed by HPV 33, 31, 52, 35, 18, 58, 56, 39, 45, 59 in CIN 2-3 and by HPV 18, 33 45, 31, 39, 52, 35, 51, 56 in cancer. HPV 16 and 18 were associated with a significantly increased cancer risk and HPV 52 and 31 with decreased cancer risk compared to the risk of CIN 3. The HPV distribution differed between histological cancer types, stages and age groups. The number of HPV types was not a significant predictor of cancer. Oncogenic HPV types were found in all persistent or recurrent CIN 2-3 disease after conization. Vaccination against HPV 16/18 is estimated to achieve a minimum 40% reduced rate of CIN 2-3 and a minimum 60% reduced cancer rate. This rate could, however, be increased to 95% and 92% respectively by including all the 12 HPV types tested for in this study.