Strategies to accelerate cervical cancer elimination in Greece: a modeling study

Abstract

Introduction: Most cervical cancer cases are caused by human papillomavirus (HPV), a vaccine-preventable infection. According to the World Health Organization (WHO), both high HPV vaccination coverage and cervical cancer screening rates will accelerate the elimination of cervical cancer, a threshold defined as <4 age-standardized cases per 100,000 women.

Methods: A dynamic transmission model was used to study the effect of increased HPV vaccination coverage and cervical cancer screening rates in Greece on cervical cancer incidence over a 100-year time horizon. Greek-specific or proxy data were used for both model inputs and calibration prior to the evaluation of eight different vaccination and screening scenarios. The estimated time to cervical cancer elimination and eradication in Greece was reported as the year each scenario reached <4 cases per 100,000 and <1 case per 100,000, respectively.

Results: Greece reached the WHO cervical cancer elimination threshold by 2074 with a 50% HPV vaccination coverage and 50% Pap test screening rate. When HPV DNA-based methods replaced Pap tests at the same rate and HPV vaccination coverage levels, the WHO threshold was reached by 2061. Other scenarios modeled future changes in HPV DNA-based screening rates with either 50% or 90% vaccination coverage. The 75% HPV DNA-based screening with 90% vaccination coverage scenario reached the WHO threshold by 2047 and the eradication threshold before the end of the century (2096).

Conclusion: If public health interventions are implemented to accelerate HPV vaccination coverage and HPV DNA-based screening adherence within the next five years, Greece can reach the WHO's cervical cancer elimination threshold by 2047 and eradicate cervical cancer before the end of the century.

Keywords: 9-valent; Greece; HPV; HPV DNA; cervical cancer; human papillomavirus vaccine; nonavalent; screening.

Figure 1

Study model ^A. Dynamic model of HPV transmission adapted for Greece (, –29). The model is structured by age, sex, sexual activity, and incorporates both direct and indirect herd immunity effects of vaccination. These features are fundamental to HPV transmission dynamics and intervention strategies, making them essential components of our model. This particular structure was chosen to effectively capture these key facets while maintaining analytical clarity. While more computationally sophisticated models, such as agent-based models, could be employed, their added value for this specific analysis would be marginal. Our model strikes an optimal balance between capturing critical epidemiological details and ensuring computational efficiency.

Figure 2

Model of cervical cancer incidence in Greece under different screening and vaccination coverage scenarios ^A. The dashed lines indicate both the World Health Organizations’ threshold of 4 cases per 100,000 for the elimination of cervical cancer as a public health problem and an aspirational threshold of 1 case per 100,000 (2). For HPV DNA-based testing, it was assumed that there was a ten-year transition from Pap tests to HPV DNA-based methods with the proportion of Pap tests decreasing linearly over time. The start of the 100-year horizon is in 2024. (A) Scenarios 1–2 represent the previous status quo of Pap screening prior to 2022 cervical cancer screening guideline changes in Greece. Scenarios 3–4 represent the current status quo of HPV DNA-based screening after the cervical cancer screening pilot program was introduced by the Greek Parliament in 2022 (25). Scenarios 1–4 all assume a 50% vaccination rate for the Greek population. (B) Scenarios 5–8 represent aspirational future increases to both cervical cancer screening and vaccination guidelines in Greece.