Decreasing Trends in Cervical Cancer Incidence among Young Women (15–34 Years) in the United States during the Human Papillomavirus (HPV) Vaccine Era

Abstract

Abstract Human papillomavirus (HPV) vaccine has been recommended for girls 11–12 years of age since 2006, with catch-up vaccination up to 26 years, to protect against most common types of HPV that cause cervical cancer. Cervical cancer incidence stabilized in women <50 years during 2008–2012. Comparing trends and incidence of cervical cancer before and during the vaccine era among vaccine-eligible young women (15–34 years) may provide valuable insight about potential vaccine impact. Methods: We examined trends in the incidence of invasive cervical cancer by race and histology among young women (15–24 years and 25–34 years) during the prevaccine era (2000–2006) and the vaccine era (2007–2013). Data were from the Surveillance, Epidemiology, and End Results (SEER) Program, including 18 SEER registry areas (Hurricane Katrina impacted Louisiana population excluded). Incidence rates (per 1,000,000) were age-adjusted to the 2010 US standard population by the direct method, using SEER*Stat software. Confidence intervals were calculated using the Tiwari method. Joinpoint regression modeling was used to compare the difference in the trends between the prevaccine era and the vaccine era. Results: Cervical cancer incidence among young women 15–24 years of age was stable during 2000–2006 from 9.5 in 2000 to 9.1 in 2006, but decreased from 6.9 in 2007 to 5.3 in 2013 (annual percentage decrease [APD] 5.7, 95% confidence interval [CI] 1.1–10.2, significantly different from the APD during 2000–2006). Cervical cancer incidence among young females 25–34 years of age also decreased from 99.7 in 2000 to 78.2 in 2006 (APD 4.0, 95% CI 2.3–5.6), and from 78.6 in 2007 to 68.2 in 2013 (APD 2.5, 95% CI 0.5–4.5). A significance decrease in the incidence was only observed in Whites, but not in Blacks, Hispanics, or Asians/Pacific Islanders. A significance decrease was observed in the incidence of non-squamous cell carcinoma (SCC) rather than SCC among young females 15–24 years from 3 in 2007 to 1.5 in 2013 (APD 9.1, 95% CI 3.1–14.7). Conclusion: A significance decrease in the incidence of cervical cancer during the vaccine era among young females 15–24 years may indicate early effects of HPV vaccination. Further research is needed to confirm this trend.