Jennifer C Spencer

Population-level health impact of hypothetical waning 1-dose human papillomavirus vaccination and 2-dose mitigation strategies in a high cervical cancer burden setting

Abstract Background We simulated the impact of hypothetical waning scenarios of a 1-dose human papillomavirus (HPV) vaccination paired with switching to 2-dose mitigation strategies guided by empirical vaccine trial reporting timelines. Methods Using 2 independent mathematical models fitted to a high-burden setting, we projected the cumulative cervical cancer cases averted over 85 years for alternative HPV vaccination scenarios under 2 program adoption timelines: 1) de novo introduction of a 1-dose HPV vaccination and 2) a switch from an existing 2-dose HPV vaccination program to a 1-dose vaccination. We assumed 80% vaccination coverage with the bivalent vaccine and an average duration of a 1-dose HPV vaccine protection of either 30 or 25 years with 100% efficacy. We varied the eligible age group(s) at program introduction and the 2-dose mitigation (single-age cohort or multi-age cohort). If needed for mitigation, reintroduction of 2-dose vaccination was assumed to occur in 2036 (ie, 30 years after initiation of the Costa Rica Vaccine Trial). Results Under both vaccine adoption timelines, the models projected that countries could achieve the same level of health benefits by switching to 2 doses in 2036 using a multi-age cohort approach as with initiating a 2-dose or 1-dose vaccination program with no waning. With only a single-age cohort 2-dose mitigation approach, 98%-99% of cases would be prevented compared with the health benefits of 2 doses or a noninferior, durable 1 dose. Conclusions Countries hesitant to adopt a 1-dose HPV vaccination program may have opportunities to leverage the benefits and efficiency of a 1-dose schedule while awaiting longer-term reporting from 1-dose durability studies, including Costa Rica Vaccine Trial.

Disparities in cervical cancer elimination time frames in the United States: a comparative modeling study

Abstract Population-level estimates in time frames for reaching cervical cancer elimination (ie, <4 cases per 100 000 women) in the United States may mask potential disparities in achieving elimination among subpopulations. We used 3 independent Cancer Intervention and Surveillance Modeling Network models to estimate differences in the time to cervical cancer elimination across 7 strata of correlated screening and human papillomavirus vaccination uptake, based on national survey data. Compared with the average population, elimination was achieved at least 22 years earlier for the high-uptake strata and at least 27 years later for the most extreme low-uptake strata. Accounting for correlated uptake impacted the population average time frame by no more than 1 year. Consequently, national average elimination time frames mask substantial disparities in reaching elimination among subpopulations. Addressing inequalities in cervical cancer control could shorten elimination time frames and would ensure more equitable elimination across populations. Furthermore, country-level elimination monitoring could be supplemented by monitoring progress in subpopulations.

Promise and Perils of Primary HPV Testing

Abstract Cervical cancer screening has reduced morbidity and mortality in many countries, but efforts to optimize screening modalities and schedules are ongoing. Using data from a randomized trial conducted in British Columbia, Canada, in conjunction with a provincial screening registry, Gottschlich and colleagues demonstrated that the estimated risk for precancerous disease (cervical intraepithelial neoplasia grades 2 or worse) at 8 years following a negative human papillomavirus (HPV) test was similar to the current standard of care (Pap testing after 3 years). The study supports extending screening intervals for those with a negative HPV test beyond currently recommended 5-year intervals. In an ideal world, the resources saved through less frequent routine cervical screening could be redirected to increasing screening uptake and follow-up of abnormalities to improve equity in cervical cancer prevention. However, implementation of extending screening intervals remains less than straightforward in settings with fragmented healthcare systems that lack information systems to support patient call/recall, such as the United States. To achieve the full promise of primary HPV testing, stakeholders at every level must commit to identifying and addressing the diverse spectrum of barriers that undergird existing inequities in care access, appropriately resource implementation strategies, and improve health information systems. See related article by Gottschlich et al., p. 904

Barriers to Cervical Cancer Screening by Sexual Orientation Among Low-Income Women in North Carolina

AbstractWe sought to examine cervical cancer screening barriers by sexual orientation among low-income women in North Carolina. The MyBodyMyTest-3 Trial recruited low-income women (< 250% of federal poverty level) aged 25–64 years who were 1+ year overdue for cervical cancer screening. We compared perceptions of cervical cancer screening among those who self-identified as lesbian, gay, bisexual, or queer (LGBQ; n = 70) to straight/heterosexual women (n = 683). For both LGBQ and straight respondents, the greatest barriers to screening were lack of health insurance (63% and 66%) and cost (49% and 50%). LGBQ respondents were more likely than straight respondents to report forgetting to screen (16% vs. 8%, p = .05), transportation barriers (10% vs. 2%, p = .001), and competing mental or physical health problems (39% vs. 27%, p = .10). Addressing access remains important for improving cervical cancer screening among those under-screened. For LGBQ women, additional attention may be needed for reminders, co-occurring health needs, and transportation barriers.

Reducing Poverty-Related Disparities in Cervical Cancer: The Role of HPV Vaccination

AbstractBackground:Near elimination of cervical cancer in the United States is possible in coming decades, yet inequities will delay this achievement for some populations. We sought to explore the effects of human papillomavirus (HPV) vaccination on disparities in cervical cancer incidence between high- and low-poverty U.S. counties.Methods:We calibrated a dynamic simulation model of HPV infection to reflect average counties in the highest and lowest quartile of poverty (percent of population below federal poverty level), incorporating data on HPV prevalence, cervical cancer screening, and HPV vaccination. We projected cervical cancer incidence through 2070, estimated absolute and relative disparities in incident cervical cancer for high- versus low-poverty counties, and compared incidence with the near-elimination target (4 cases/100,000 women annually).Results:We estimated that, on average, low-poverty counties will achieve near-elimination targets 14 years earlier than high-poverty counties (2029 vs. 2043). Absolute disparities by county poverty will decrease, but relative differences are estimated to increase. We estimate 21,604 cumulative excess cervical cancer cases in high-poverty counties over the next 50 years. Increasing HPV vaccine coverage nationally to the Healthy People 2020 goal (80%) would reduce excess cancer cases, but not alter estimated time to reach the near-elimination threshold.Conclusions:High-poverty U.S. counties will likely be delayed in achieving near-elimination targets for cervical cancer and as a result will experience thousands of potentially preventable cancers.Impact:Alongside vaccination efforts, it is important to address the role of social determinants and health care access in driving persistent inequities by area poverty.

Potential effectiveness of a therapeutic HPV intervention campaign in Uganda

AbstractCervical cancer is a major source of morbidity and mortality in Uganda. In addition to prophylactic HPV vaccination, secondary prevention strategies are needed to reduce cancer burden. We evaluated the potential cancer reductions associated with a hypothetical single‐contact therapeutic HPV intervention—with 70% coverage and variable efficacy [30%‐100%]—using a three‐stage HPV modeling framework reflecting HPV and cervical cancer burden in Uganda. In the reference case, we assumed prophylactic preadolescent HPV vaccination starting in 2020 with 70% coverage. A one‐time therapeutic intervention targeting 35‐year‐old women in 2025 (not age‐eligible for prophylactic vaccination) averted 1801 cervical cancers per 100 000 women over their lifetime (100% efficacy) or 533 cancers per 100 000 (30% efficacy). Benefits were considerably smaller in birth cohorts eligible for prophylactic HPV vaccination (768 cases averted per 100 000 at 100% efficacy). Evaluating the population‐level impact over 40 years, we found introduction of a therapeutic intervention in 2025 with 100% efficacy targeted annually to 30‐year‐old women averted 139 000 incident cervical cancers in Uganda. This benefit was greatly reduced if efficacy was lower (30% efficacy; 41 000 cases averted), introduction was delayed (2040 introduction; 72 000 cases averted) or both (22 000 cases averted). We demonstrate the potential benefits of a single‐contact HPV therapeutic intervention in a low‐income setting, but show the importance of high therapeutic efficacy and early introduction timing relative to existing prophylactic programs. Reduced benefits from a less efficacious intervention may be somewhat offset if available within a shorter time frame.

Adapting a model of cervical carcinogenesis to self-identified Black women to evaluate racial disparities in the United States

Abstract Background Self-identified Black women in the United States have higher cervical cancer incidence and mortality than the general population, but these differences have not been clearly attributed across described cancer care inequities. Methods A previously established microsimulation model of cervical cancer was adapted to reflect demographic, screening, and survival data for Black US women and compared with a model reflecting data for all US women. Each model input with stratified data (all-cause mortality, hysterectomy rates, screening frequency, screening modality, follow-up, and cancer survival) was sequentially replaced with Black-race specific data to arrive at a fully specified model reflecting Black women. At each step, we estimated the relative contribution of inputs to observed disparities. Results Estimated (hysterectomy-adjusted) cervical cancer incidence was 8.6 per 100 000 in the all-race model vs 10.8 per 100 000 in the Black-race model (relative risk [RR] = 1.24, range = 1.23-1.27). Estimated all-race cervical cancer mortality was 2.9 per 100 000 vs 5.5 per 100 000 in the Black-race model (RR = 1.92, range = 1.85-2.00). We found the largest contributors of incidence disparities were follow-up from positive screening results (47.3% of the total disparity) and screening frequency (32.7%). For mortality disparities, the largest contributor was cancer survival differences (70.1%) followed by screening follow-up (12.7%). Conclusion To reduce disparities in cervical cancer incidence and mortality, it is important to understand and address differences in care access and quality across the continuum of care. Focusing on the practices and policies that drive differences in treatment and follow-up from cervical abnormalities may have the highest impact.