HPV subtypes and immunological parameters of cervical cancer in Iceland during two time periods, 1958–1960 and 1995–1996

Cervical cancer is a disease caused in part by an infection with an oncogenic subtype of human papillomavirus (HPV). In this study we analysed all cervical cancer samples diagnosed in Iceland during two periods, 1958–1960 and 1995–1996, and asked whether significant changes in viral or immunological parameters had occurred over a period that spanned both significant changes in sexual attitude and the implementation of organized screening for cervical cancer. Samples from 47 patients (46 squamous cell carcinomas (SCC) and 1 adenosquamous carcinoma (ASC)) in the first period and 30 patients (20 SCC, 4 ASC, and 6 adenocarcinomas (AC)) in the later period were analysed for viral subtype and expression of Fas, FasL, MHC class I, p53 and apoptosis. AC and ASC are proportionately much more common today than 40 years ago (30% vs 2%). The distribution of HPV in cervical cancer is similar in both periods, with HPV16 found in 75% and HPV18 in 13% of cases. Other HPV types found were 31,33,45, and 59. No significant differences were found in the immunological profiles of tumors from the two periods except that a higher fraction of SCC in the later period stained positive for FasL. When SCC are compared with AC/ASC, the latter have less expression of MHC class I, less expression of Fas, and stronger FasL expression. AC/ASC tumors show some immunological features that suggest that they are more resistant to immune attack than SCC.