Effect of Thermal Ablation on Persistent HPV Infection in Danish Women ≥40 Years of Age; a Randomized Clinical Study

Persistent infection with high-risk human papillomavirus (HR-HPV) is the etiological cause of precancerous cervical intraepithelial neoplasia (CIN) and ultimately cervical cancer (CC)1. With 50 years of cervical cancer screening in Denmark, CC incidence has been reduced from the peak of 39.6/100.000 in 1966 to 11/100.000 in 20222, but the World Health Organization world elimination goal of 6/100.0003,4 is still in the distance.

Cervical cancer is largely preventable through local treatment of screen-detected cervical precursor lesions also known as cervical intraepithelial neoplasia (CIN). Infection with the HPV virus causes cell changes and cervical cancer5. The HPV virus infects the cells on the surface of the cervix. While most women naturally clear an HPV infection over time, in approx. 10% of all infected women, the HPV infection becomes persistent which is a known risk enhancer6-8. It is unknown why an HPV infection becomes chronic in some but not most women. Lifetime risk of HPV infection is over 80%. In Denmark, all women between 23-65 years are offered screening for cervical cancer at defined intervals. Today, cervical screening is conducted using a combination of cell-based evaluation, cytology, and molecular HPV screening. However, Danish cervical cancer screening is in transit from cytology to molecular HPV based screening to all women aged 30 to 649. A recurrent issue with HPV based screening is the specificity of the screening which leads to many women being referred for monitoring or follow up without having significant disease. The screening program constitute 400,000 individual annual screening samples and approx. 30,000 tissue biopsy sets are derived as follow-up after a positive screening sample. From these, 6500 cone sections results.

Cervical cancer incidence in Denmark displays a double peaked pattern with the highest incidence in women 35-45 years and again in women 70-75 years. The latter peak is closely related to the current exit age from screening which is 64 years compared to 70 in the other Nordic countries. From 2012-2016, the average annual number of new CCs was 371 with 103 annual deaths10. In Denmark, women aged ≥ 60 years accounts for more than half of CC deaths (66%) and almost 30% of new cases10. For older women as well as younger, a clinical challenge is that many carry a persistent HPV infection which may or may not give rise to severe dysplasia possibly preceding cancer. However, current diagnostic methodologies offer no safe way to distinguish between the progressive lesions and persistent, non-progressive HPV infections. This leads to a large group of persistent HPV positive women in extended clinical follow-up regimens without a clear exit strategy and eventually leading to (over)treatment in the form of conization or hysterectomy. DNA methylation of human genes has shown to be particularly sensitive for the detection of cervical cancer and advanced CIN2 or 3 and presumed increased short-term risk of progression to cervical cancer11-17. Absence of host-cell DNA methylation on the other hand, is associated with regression of CIN2/313,17.

This PhD project focusses on whether novel methylation biomarkers can assist in risk-stratification for risk of severe cervical disease in two groups of women with persistent human papillomavirus (HPV) infections:

• Women who have received thermal ablation as part of treatment for non-severe cell changes following HPV infection (randomized control trial, Region Zealand)
• Women 60-64 years of age with persistent HPV infections participating in cervical cancer screening in the Capital Region of Denmark If successful, the project will provide needed data to support introduction of molecular triage biomarkers in two different applications; to determine persistent HPV infection after thermal ablation treatment and to risk stratify women aged 60-64 years before conclusion of screening program participation18. The project is a collaboration between 1) Region Zealand and Capital Region of Denmark, and 2) Capital Region of Denmark and Central Denmark Region.