New study: Papillomavirus types range substantially in their risk of progression to cervical precancerous lesion and cancer

Different human papillomavirus types vary substantially in their ability to cause severe cervical cytological abnormalities and cancer. Novel research results will help to enhance cervical cancer screening to more precise and risk-based approach.

Human papillomavirus (HPV) is a necessary cause of cervical cancer but the risk of severe cervical lesions substantially varies according to HPV type. In Finland, the number of new cervical cancers is close to 200 per year, and around 2 100 women are diagnosed with severe cervical precancerous lesion.  Around 55 women die from cervical cancer annually.

Research collaboration between the Finnish Institute for Health and Welfare (THL), Finnish Cancer Registry, Helsinki University Hospital (HUS) and Karolinska Institutet provides new information on HPV types carrying the highest and lowest risk for cervical lesions and how these results could be utilized in cervical cancer screening.

This was the first study to assess HPV type-specific risk for severe cervical lesions by age group and by different screening test result. 

As of today, management of people testing positive for HPV is similar regardless of the HPV type. Since HPV infection is very common, the number of individuals referred for diagnostic confirmation has increased substantially after the switch to primary HPV test in cervical cancer screening creating burden on healthcare.

”When we know which HPV infections warrant more intensive monitoring, we can better allocate the resources for monitoring and diagnostic confirmation based on individual risk and to avoid unnecessary follow-up test and procedures”, says the Principal Investigator of the study, Chief Clinician Maarit Leinonen from THL.

Long-term follow-up reveals differences between HPV types

Study found that the risk of severe cervical precancerous lesion and cancer substantially varied according to HPV type.

Around 20-40 % of people testing positive for the highest risk HPV types developed severe cervical lesions during the follow-up. With the lowest risk HPV types, the probability of being diagnosed with severe cervical precancerous lesion or cancer was only around 5-7 %. 

The risk of severe cervical lesion also varied according to the triage Pap test result. Some high-risk HPV types were associated with an elevated risk of severe lesions even in the presence of normal cytology in the Pap test. Conversely, some HPV types showed low associated risk even when cytological abnormalities were present in the Pap test.

”Our results emphasize the importance of specific HPV type in the individual risk assessment in cervical cancer screening. In the future, different HPV types will certainly be managed on a different manner in cervical cancer screening according to their risk profile”, says researcher Maija Vahteristo from the Finnish Cancer Registry.

Study utilized cervical screening samples collected in early 2000s. HPV-positive samples were genotyped in the laboratory. The genotyping data were linked to data from several nationwide health registries which allowed linkage between the HPV infection and later developing cervical lesion. Comprehensive register data together with long, up to 18 years, follow-up provided reliable HPV type-specific results.

HPV vaccination will impact future cervical cancer screening programme

HPV-related cancers can also be prevented by vaccine. HPV vaccine is included in Finland's national vaccination programme and provided to all pupils in grades 5-6. 

HPV vaccination will have a significant impact on future cervical cancer screening programme because vaccinated people have excellent protection against HPV-related cancers and precancers.

Currently a major question is how to adapt cervical cancer screening programmes and what is the most optimal screening strategy for HPV vaccinated people having low risk for cancer. Results from this research collaboration will help ongoing research on this topic and modelling of different scenarios.

Results have been published in an academic journal International Journal of Cancer.
Long-term human papillomavirus genotype-specific risk of cervical high-grade intraepithelial lesion and cancer—By age group and triage cytology

Lisätietoja

Maarit Leinonen
Chief Clinician
THL
tel. 029 524 7640
[email protected]

Maija Vahteristo
Researcher
Finnish Cancer Registry
tel. 0407562161
firstname.lastname @cancer.fi