To Örebro University

The droplet digital PCR (ddPCR) system enables high-sensitivity detection of nucleic acids and direct absolute quantification of the targets. The aim of this research was to evaluate this system for viral load (VL) analysis of the human papillomavirus (HPV) genotypes HPV31, 35, 39, 51 and 56 measured in number of viral particles per cell. The sample types used for the optimization of the ddPCR assay were formalin-fixed paraffin-embedded (FFPE) tissues and cervical liquid cytology samples. The presently optimized ddPCR assays, together with assays optimized previously for HPV16, 18, 33 and 45, with the same ddPCR method, were used for the VL analysis of cervical tumor samples. Results published previously on the present study cohort showed that women with a cervical tumor containing multiple high-risk HPV genotypes had a worse prognosis compared to women with single-genotype-infected tumors. The VL was therefore analyzed in this study for the same cohort, as a possible explanatory factor to the prognostic differences. The results of the optimization part of the study, with analysis of VL using ddPCR in DNA from varying sample types (FFPE and liquid cytology samples), showed that each of the five assays demonstrated good inter- and intra-assay means with a coefficient of variation (CV) under 8% and 6% respectably. The cohort results showed no difference in VL between tumors with multiple and single HPV infections, and therefore did most likely not constitute a contributing factor for prognostic differences observed previously. However, tumors from women aged 60 years or older or containing certain HPV genotypes and genotype genera were associated with a higher VL.

Despite the common perception that the human papilloma virus (HPV) is a requirement for the development of cervical cancer (CC), a considerable number of CCs test HPV negative. Presently, many countries are shifting to HPV primary CC screening, and it is of importance to increase the knowledge about the group of CCs that test HPV negative. The aim of this study was to reinvestigate a proportion of cervical tumors with a primary negative or invalid test result. Reinvestigation with repeated genotyping (targeting L1) was followed by analysis with an alternative target method (targeting E6/E7) on existing or additional tumor material. Consistently negative tumors were histologically evaluated, and cases with low or lacking tumor cell content, consistent invalid test results, or with suspicion of other than cervical origin were excluded. HPV-negative cases were thereafter subjected to immunohistochemistry (Cytokeratin 5, pan cytokeratin, protein 63, P16, and P53). The HPV-negative proportion could after reinvestigation be reduced by one-half (14%-7%). Additional positive samples were often detected in late polymerase chain reaction cycles, with an alternative (E6/E7) or the same (L1) target, or with a method using shorter amplicon lengths. Confirmed HPV negativity was significantly associated with worse prognosis, high patient age, longer storage time, and adenocarcinoma histology. Some of the HPV-negative cases showed strong/diffuse p16 immunoreactivity, indicating some remaining false-negative cases. False HPV negativity in this cohort was mainly linked to methodological limitations in the analysis of stored CC material. The small proportion of presumably true HPV-negative adenocarcinomas is not a reason for hesitation in revision to CC screening with primary HPV testing.

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.

Background: An updated screening algorithm was introduced in Sweden 2015. Primary HPV test for women >30 years old and a prolonged screening with the last test after 64 years of age were some of the changes. In the region of Örebro County, the previous cut-off age was 60 years and with a screening interval of 5 years, women left their last sample when they were 55-59 years old. In the shift between two screening programs, a group of women, 60-64 years old, that left the program 5-10 years ago were now included in the new screening. For re-inclusion, a two year long program was formed to catch-up this group of women and screen them according to the new screening algorithm. At the same time a research project investigating self-sampling was launched. At the same time as the women were invited for a last screening sample they were also asked to participate in a study where they should take a vaginal self-test up to one week after their ordinary screening sample was taken by a midwife.

Method: Postmenopausal women between 64-70 years was included in the study. HPV status in samples from midwife sampling (MS) was compared to self-sampling (SS) samples. HPV was analyzed using HPV Aptima and all HPV positive samples, independent of sampling method, was triaged with cytology and followed-up according to national guidelines.

Results: So far, 585 women with paired samples have been included in the study. In the MS, 4% of the women are positive for hrHPV compared to 11% in the SS group. In 486/585 women, the results of the two samples are concordant. Among the non-concordant samples (13%), 62% were positive in SS and negative in MS. The opposite, negative in SS and positive in MS were seen in 4% of the samples. Among the MS negative samples, 32% were invalid in SS. Cytology was used as a triage test for HPV positive women, both for MS and SS. Of 23 hrHPV positive, 18 had normal cytology, 2 ASCUS, 1 LSIL and 1 HSIL. In the samples with abnormal cytology, 4/5 were hrHPV positive in both SS and MS. One sample was positive in SS but negative in MS.

Discussion: In this age group, more women are hrHPV positive in SS compared to MS. This is in line with what other have seen. Among the very few hrHPV positive samples with abnormal cytology, the majority was hrHPV positive in both MS and SS. But since cytology is a poor triage marker in this age group clinical follow-up is needed before the effectiveness of the both sampling methods can be concluded.

OBJECTIVE: To investigate whether self-sampling is as reliable as professional sampling for HPV testing and genotype detection among postmenopausal women.

METHODS: In the present prospective cross-sectional study, women in Örebro County, Sweden, who had high-risk HPV (hrHPV) and normal cytology results in exit screening tests conducted in between January 1, 2012, and December 31, 2014, were invited to follow-up screenings between February 24, 2015 and May 15, 2015, that included professional sampling and self-sampling. HPV genotypes were identified by a DNA-based assay that could detect 35 HPV genotypes. Findings between the different sampling methods were compared.

RESULTS: Of 143 women who participated, 119 returned a self-sample. Completely concordant results were observed in 67 of these samples when both hrHPV and low-risk HPV genotypes were analyzed. Overall, 99 (83.2%) women had the same clinically relevant finding from both sampling methods. Twenty women had discordant hrHPV results (hrHPV detected in 10 self-samples vs 10 professionally collected samples; Cohen κ 0.66, 95% confidence interval 0.53-0.80). There was no significant difference between the two sampling methods for clinically significant infections (P>0.99) or extended genotyping (P=0.827).

CONCLUSION: Postmenopausal women could be offered self-sampling devices to increase screening-program coverage while maintaining test quality.

Cervical cancer (CC) is one of the most common cancers in women and virtually all cases of CC are a result of a persistent infection of human papillomavirus (HPV). For disease detected in early stages there is curing treatment but when diagnosed late with recurring disease and metastasis there are limited possibilities. Here we evaluate HPV impact on treatment resistance and metastatic disease progression. Prevalence and distribution of HPV genotypes and HPV16 variants in a Swedish CC patient cohort (n=209) was evaluated, as well as HPV influence on patient prognosis. Tumor samples suitable for analysis (n=204) were genotyped using two different real-time PCR methods. HPV16 variant analysis was made using pyrosequencing. Results showed that HPV prevalence in the total series was 93%. Of the HPV-positive samples, 13% contained multiple infections, typically with two high-risk HPV together. Primary cure rate for the complete series was 95%. Recurrence rate of the complete series was 28% and distant recurrences were most frequent (20%). Patients with tumors containing multiple HPV-strains and particularly HPV genotypes belonging to the alpha 7 and 9 species together had a significantly higher rate of distant tumor recurrences and worse cancer-specific survival rate.