Predictive Model Projects Cervical Cancer Elimination

A predictive model estimated that cervical cancer could be virtually eliminated in the United States by 2030 in communities with low poverty rates, but not until 2044 in communities with high poverty rates.

There are approximately 14,000 cases of cervical cancer diagnoses each year in the United States, leading to about 4,000 annual deaths. Over 90 percent of cervical cancers are caused by certain types of human papillomavirus (HPV) infections.

HPV vaccines became available in 2006 and currently protect against nine HPV types, including seven of the 14 known to increase cancer risk. The vaccine regimen is recommended for all adolescents and consist of two doses for children aged nine to 15 or three doses for individuals ages 15 to 26.

With the vaccine being 90 percent effective at preventing HPV-related cancers, vaccination efforts could lead to “near-elimination” of cervical cancer.

Jennifer Spencer, PhD, an assistant professor at the University of Texas at Austin, performed this work as a research fellow at the Harvard School of Public Health. Spencer and her colleagues constructed a model of HPV spread and progression based on previous models used to understand sexually transmitted diseases.

The model accounted for the risk of HPV transmission among vaccinated and unvaccinated individuals, the probability of HPV progressing to cervical cancer, the rates of cervical cancer screenings, and the likelihood of effective cancer treatment.

The research team created two versions of the model, one of a hypothetical county in the lowest poverty quartile and one of a county in the highest poverty quartile.

Immunization data for low- versus high-poverty areas was received from the National Immunization Survey-Teen (NIS-Teen) while screening and follow-up data were acquired from the National Interview Survey (NHIS).  Additionally, the researchers got HPV prevalence data from the National Health and Nutrition Examination Survey (NHANES).

The predictive models that best matched the existing data for low- and high-poverty scenarios were then used to simulate cervical cancer rates through 2070. The researchers ran the simulation using the current vaccine initiation rate of around 70 percent in both high- and low-poverty counties, as well as the US target vaccination rate of 80 percent.

The model results predicted that low-poverty areas will reach the cervical cancer near-elimination threshold by 2030, while high-poverty areas will not reach the threshold until 2044. These results indicate an estimated 21,604 excess cervical cancer cases in high-poverty areas over the next 50 years.

Spencer does not suspect these health disparities are due to differences in vaccination rates.

“Other studies have predicted that, as a whole, the US will hit the elimination target in the middle of that range,” Spencer said in a press release. “The fact that some places will hit it a decade before other places is a little bit of a gut punch.”

“Vaccination can do a lot of good, but it’s unlikely that the disparities can be addressed through just vaccination,” she added. “The next step is to identify what policies we can use to close these gaps in the future.”

The study confirmed that known differences in cervical cancer screening rates between high- and low-poverty counties. Additionally, researchers found that high-poverty counties have higher rates of cancer-causing HPV types that are not covered by the vaccine, 8.3 percent compared to 8.9 percent in low-poverty counties.