High-poverty areas may lag behind others in cervical cancer elimination
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Although cervical cancer elimination appears to be within reach in the United States, a predictive model anticipated an approximately decade-long gap between low-poverty and high-poverty areas of the country in achieving this goal.
“This study was motivated by some early studies suggesting HPV vaccination in high-poverty settings might be similar — or even higher — than vaccination in low-poverty settings,” Jennifer C. Spencer, PhD, assistant professor at The University of Texas at Austin, who conducted the study as a research fellow at Harvard School of Public Health, said in an interview with Healio. “In the context of decades of studies showing stark disparities in cervical cancer incidence, with high-poverty counties having rates about 40% higher than low-poverty counties, we wanted to see what the impact of these vaccination patterns might be on these disparities in the long term.”
In the study, published in Cancer Epidemiology, Biomarkers & Prevention, Spencer and colleagues produced a model of HPV transmission and progression based on prior models aimed at understanding STDs.
Spencer and colleagues’ model assessed the risk for HPV spread among both vaccinated and unvaccinated people, the likelihood of HPV progressing to cervical cancer, rates of cervical cancer screening, and the chances of effective cancer treatment. They generated two versions of the model, one involving a hypothetical county in the lowest quartile of poverty and one representing a county in the highest quartile of poverty. They utilized immunization information for low- vs. high-poverty areas from the National Immunization Survey-Teen (NIS-Teen), screening and follow-up data from the National Health Interview Survey (NHIS) and HPV prevalence data from the National Health and Nutrition Examination Survey (NHANES). They used the models that best matched existing data for the low- and high-poverty areas to simulate cervical cancer rates through 2070.
The researchers conducted the simulation using the current 70% rate of vaccine initiation (receipt of at least one dose), in both high- and low-poverty counties, and used the national target vaccination rate of 80%.
Based on the models, the researchers estimated that low-poverty areas will arrive at the cervical cancer near-elimination level by 2030, whereas high-poverty areas will not achieve this target until 2044. This delay would mean approximately 21,604 additional cervical cancer cases in high-poverty areas over the next 50 years.
However, a decrease is anticipated in the absolute disparity in cervical cancer rates, from 2.5 excess cases per 100,000 women in high-poverty regions in 2006 to one excess case per 100,000 women in high-poverty areas in 2070.
The model did not show that cervical cancer would be eradicated much sooner in either high- or low-poverty areas if vaccination rates reached 80%, but did estimate that such efforts would reduce the number of excess cases in high-poverty counties by approximately 1,000 over the next 50 years.
Spencer said the disparities seen in the study cannot be attributed to differences in vaccination rates, because high- and low-poverty areas had similar vaccination rates. Instead, the study noted that known differences in cervical cancer screening rates between high- and low-poverty counties likely contributed to the disparities identified by the model.
Roughly 14,000 cases of cervical cancer are diagnosed annually in the U.S., leading to an estimated 4,000 deaths per year. Infection with certain types of HPV is the cause of more than 90% of cervical cancer cases. HPV infection can also cause anal, penile, vaginal, vulvar and oropharyngeal tumors.
HPV vaccines, which became available in 2006, currently protect against nine HPV types, including half of the 14 associated with increased cancer risk. Full vaccination is recommended for all adolescents and includes two doses for children aged 9 to 15 years or three doses for patients aged 15 to 26 years. The vaccine is more than 90% effective at preventing HPV-related cancers. This may lead to “near-elimination” of cervical cancer, defined by WHO as fewer than four cases per 100,000 individuals.
“I think one thing this study shows is that the problems creating disparities are multilevel, and it will take a multilevel approach to fully close these gaps. Improving screening can’t save lives if there isn’t support for those who have an abnormality identified to get appropriate workups, monitoring or treatment,” Spencer told Healio. “So, improving insurance coverage and making screening more accessible might be solutions, but also things like patient navigation to make sure that once patients have their results, they can take the appropriate next steps.”
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Spencer JC, et al. Cancer Epidemiol Biomarkers Prev. 2021;doi:10.1158/1055-9965.EPI-21-0307.
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