140 - Incidence of Cervical Cancer Subtypes in Relation to HPV Vaccination Uptake in the U.S.

P. L. Lee¹, A. Lukez¹, K. J. Howell¹, G. Mantia-Smaldone², and J. G. Price³; ¹Department of Radiation Oncology, Fox Chase Cancer Center, Philadelphia, PA, ²Department of Surgical Oncology - Gynecologic Oncology, Fox Chase Cancer Center, Philadelphia, PA, ³Fox Chase Cancer Center at Temple University Hospital, Philadelphia, PA

Purpose/Objective(s): We aim to assess changes in cervical cancer and subtype incidence with respect to the introduction of a human papilloma virus (HPV) vaccine in the United States (USA). We hypothesize a decrease in cervical cancer incidence in an age group with highest anticipated vaccine uptake (18-25 years) versus all ages. We also anticipate altered incidence of squamous cell and adenocarcinoma in the 18-25 age group. Materials/

Methods: We conducted a retrospective population based cross-sectional study using data recorded from the USCS Public Use Database from 2000-2020 of SEER 22. Vaccination rates were obtained from the NIS-Teen, which includes adolescents aged 13-17, from 2006-2022. SEER*Stat software was queried for cervical cancer incidence, and stratified by histology. Joinpoint Regression 5.0.2 and Prism 10.1.1 were used to calculate trends. Data from 2020 were plotted but excluded from regression analysis due to the impact of COVID-19 on cancer diagnoses.
Results: There was rapid uptake of HPV vaccine in the USA after its introduction in 2006. Female teens aged 13-17 receiving at least 1 dose of HPV vaccine began at 25% in 2007, surpassed 50% by 2011, and rose to 73% in 2019. Regarding cervical cancer, incidence among all ages was in decline from 2000-2011, with 2011 identified by Joinpoint regression as a significant point suggesting a change in trend. From 2000-2011 cervical cancer rates declined from 9.95 per 100,000 to 7.71, with an average annual change (AAC) of -0.162 (p < 0.05). From 2011-2019 rates stabilized with an AAC of 0.023, not statistically significant from zero. In contrast, among 18-25 year olds, we find stable rates of cervical cancer diagnosis from 2000-2009 (Joinpoint 1) with an AAC of 0.005, not significant from zero. From 2009-2019, rates down trended from 1.55 to 0.51, with an AAC of -0.088 (p < 0.05). On subtype analysis in 18-25 year olds, only squamous cell histology had a significant Joinpoint, identified at 2011. AAC from 2000-2011 was -0.014, and from 2011-2019 was -0.055 (p < 0.05), representing a decline in incidence from 0.74 in 2011 to 0.32 in 2019. Adenocarcinoma subtype did not have any Joinpoints to signal a change in trend, with an AAC from 2000-2019 of -0.003.
Conclusion: We find rapid HPV vaccine uptake from 2007-2011, and continued steady rise through 2020. Concurrently there was significant downward trend in cervical cancer incidence among women aged 18-25 beginning in 2009, contrasting stable cervical cancer rates in all women since 2011. On subtype analysis, squamous histology in 18-25 year olds had a significant downward trend beginning in 2011. Adenocarcinoma subtype had no change in trend from 2000-2019. There appears to be decreasing cervical cancer incidence in an age group likely to have significant HPV vaccine uptake. There may be a preferential benefit for squamous histology, which may lead to eventual changes in the distribution of cervical cancer subtypes. Future population based analyses are warranted as the impact of HPV vaccination continues to mature.