To Örebro University

Cervical cancer (CC) is caused by a persistent infection of certain types of the human papillomavirus (HPV). Even though great progress has been made in strategies for prevention, and treatment of CC, there is still a need for improved methods in screening and management of women diagnosed with CC. The aim of this thesis was to gain further knowledge of CC by studying HPV-related or cellular biomarkers in precursors and established cancer.

Mostly molecular methods were used for analysis of both tumour and screening samples. Among the studied biomarkers were HPV genotype, HPV multiplicity, viral load and methylation.

Initially, HPV was detected in only 86% of the tumours; after careful reinvestigation of the negative samples, the final prevalence was 93%. The results show that analysis of long-term archived samples may require thorough and repeated analysis to obtain accurate results. In the HPV-positive tumour samples, 13% tested positive for multiple genotypes. This finding was associated with poor prognosis for the woman and could be a useful biomarker for prognostic assessment in CC. Viral load was analysed as a potential contributing factor for prognosis differences, however, no such association was detected.

In the screening cohort, 40% of women with high-grade abnormalities were positive for HPV16 and 18, genotypes included in the vaccine used since 2012 in Sweden, while 88% were positive for the genotypes in the updated vaccine used since 2019. This indicates a large future reduction of high-grade abnormalities in the vaccinated cohorts, and baseline data like these are valuable for surveillance of genotype distribution in the coming decades. A methylation test targeting two human genes, proposed for use in screening, was tested on the screening samples. We detected no association between hypermethylation and HPV, but it was associated with increasing age, something that needs to be considered if using this method in screening.