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Estimating the impact of HIV on cervical cancer elimination: a comparative modelling analysis in South Africa

Title
Estimating the impact of HIV on cervical cancer elimination: a comparative modelling analysis in South Africa
Presenter
Shona Dalal
Authors
C. van Schalkwyk (1), M.-C. Boily (2), R. Barnabas (3), C. Bayer (3), M. Rönn (4), G. Liu (3), D. Rao (3), N. Soni (2), L. Johnson (5), M. Brisson (6), P. Bloem (7), S. Gottlieb (8), N. Broutet (8), S. Dalal * (9)
Institutions
(1) University of Stellenbosch, SACEMA, Stellenbosch, South Africa, (2) Imperial College London, MRC Centre for Global Infectious Disease Analysis, School of Public Health, London, United Kingdom, (3) University of Washington, Global Health and Allergy and Infectious Diseases, Washington, United States, (4) Harvard T.H. Chan School of Public Health, Department of Global Health and Population, Boston, United States, (5) University of Cape Town, Centre for Infectious Disease Epidemiology and Research, Cape Town, South Africa, (6) Université Laval, Département de médecine sociale et préventive, Quebec, Canada, (7) World Health Organization, Department of Immunization, Vaccines & Biologicals, Geneva, Switzerland, (8) World Health Organization, Department of Sexual and Reproductive Health and Research, Geneva, Switzerland, (9) World Health Organization, Department of Global HIV, Hepatitis and STIs Programmes, Geneva, Switzerland

BACKGROUND: Sub-Saharan Africa carries the largest global burden of both cervical cancer and HIV. Women living with HIV (WLHIV) have a six-fold higher risk of cervical cancer compared to women without HIV, bringing into question the impact of HIV on recommended cervical cancer elimination strategies in high HIV prevalence settings. We conducted comparative modelling as part of WHO's Cervical Cancer Elimination Modelling Consortium to estimate the potential for eliminating cervical cancer in South Africa.
METHODS: Three dynamic models, calibrated to South African data, simulated HIV and HPV transmission in age-, sex-, and risk-stratified populations, considering the underlying natural histories and interactions between the two infections. Base-case interventions for HIV were: condom use, male circumcision, and antiretroviral therapy, reaching 90-90-90 targets and 70% male circumcision by 2030, and for cervical cancer: no vaccination and baseline screening. We estimated the impact of WHO-recommended cervical cancer prevention strategies introduced in 2020 on cervical cancer incidence over 100 years including 90% girls vaccinated at ages 9-14 years, 90% women screened twice, 90% treated (WHO strategy), with specific strategies for WLHIV: (1) multi-age-cohort vaccination up to age 24 years, and 2) three-yearly HPV screening and treatment between ages 25-50 years (WLHIV strategy). We present results as the median and range from the three models.
RESULTS: All models predict that elimination of cervical cancer (age-standardised incidence rate of <4 cases/100,000 women) is possible by 2081 (range 2067-2093) with the WHO strategy. Although cervical cancer incidence is unlikely to reach the elimination threshold among WLHIV, a reduction to <10 cases/100,000 could be achieved by 2086 (2069-2120). The WHO strategy is expected to prevent 28% (17-32%) of cervical cancer cases overall, and 27% (16-30%) in WLHIV over the next 25 years compared to the base-case. Compared to the WHO strategy alone, the WLHIV strategy is expected to prevent an additional 24% (17-27%) of cervical cancer cases among WLHIV over the next 25 years.
CONCLUSIONS: Cervical cancer elimination in South Africa is plausible within the next century with WHO's recommended strategy. In the short term, cervical cancer cases can be substantially reduced if WLHIV receive vaccination and additional screening.