Modelling Impact of Prevention Strategies on Cervical Cancer Incidence in SA
Prof Alex Welte
- The DST/NRF Centre of Excellence in Epidemiological Modelling and Analysis (SACEMA), University of Stellenbosch
Title of the project
Modelling the impact of prevention strategies on cervical cancer incidence in South Africa.
This is a collaborative project between the DST/NRF Centre of Excellence in Epidemiological Modelling (SACEMA) at the University of Stellenbosch and the Centre for Infectious Disease Epidemiology and Research (CIDER) at the University of Cape Town. The team consists of epidemiological modellers who aim to estimate the long term impact of prevention strategies, such as human papillomavirus (HPV) vaccination and screening, on cervical cancer incidence. Valuable clinical input will be provided by Prof Jennifer Moodley, the director of cancer research at the University of Cape Town.
In recent years, mathematical models are increasingly applied to cervical cancer research. Globally, but particularly important for the South African context, existing models share the limitation that the well-established interaction between HIV and HPV is not dynamically simulated, and therefore the need exists for a sophisticated model that fully incorporates the effect of HIV on HPV incidence and cervical disease progression. This study proposes to 1) extend an individual-based HIV/STI model to include HPV and its progression to cervical cancer, calibrate the model to South African HPV and HIV prevalence data and validate the model with cervical cancer incidence data and 2) evaluate the potential impact of various prevention methods on cervical cancer incidence.
HIV is well known as the most devastating sexually transmitted infection of our time, perhaps ever. Human papilloma virus is fairly well known from its tendency to cause genital warts and, in some cases, cancers. The HIV epidemic has interacted disastrously with preexisting TB infection cycles in much of southern African, and it has been of considerable interest to understand the interactions between HIV and other important infections – particularly sexually transmitted ones like HPV. In particular, while it is well known that HIV infection compromises the immune system and exacerbates many other illnesses (like TB) – it is also plausible that HIV infection can make people more likely to contract other infections to which they are potentially exposed. In the case of HPV, there has been suspicion that HIV makes subsequent acquisition of HIV more likely. What we have shown, by simulating a transmission network as best as we can at this point, is that is it entirely plausible to see the patterns of HPV that we see, without having to invoke such an effect. This is because the crucial risk factor – unprotected sex – is shared between these two infections, leading to complex interactions which can mimic risk-enhancement.