Human papillomavirus vaccination for young survivors of cancer

Human papillomavirus (HPV) vaccine can prevent six types of cancers and has a strong safety profile. However, only 55% of US adolescents (ie, aged 13–15 years) are up to date on HPV vaccination.¹ This proportion is well below the Healthy People 2030 goal of 80% and coverage for other adolescent vaccines of almost 90%.¹ HPV vaccination rates also decreased notably during the COVID-19 pandemic, a problem that was probably amplified for survivors of cancer. Low uptake of HPV vaccine is an especially pressing problem for adolescent and young adult (AYA) survivors of cancer, whose risk of a new cancer diagnosis is 3–10 times higher than the general population.²

A study by Wendy Landier and colleagues in The Lancet Child & Adolescent Health ³ shows that HPV vaccine is most likely effective for AYA survivors of cancer. In this single-arm, non-inferiority trial in the USA, survivors of cancer who were aged 9–26 years received three doses of quadrivalent or nonavalent HPV vaccine over 6 months. The study noted that antibody response against HPV types 16 and 18 in survivors of cancer was non-inferior to estimates for the general population in other studies. Indeed, survivors of cancer appeared to mount an even more vigorous immune response than did the general population in 15 of 16 subgroup analyses. Although it is not yet known what level of immune response confers protection against HPV-related cancers, immunobridging studies such as this are a standard tool for understanding how a vaccine will perform where a full trial might not be feasible.

Unfortunately, uptake of HPV vaccine appears to be lower among AYA survivors of cancer than among the general population. In a US study of 982 AYA survivors of cancer, uptake of HPV vaccine was lower than were national estimates for adolescents in the general population (ie, 24% vs 41%).⁴ The deficit existed for all subgroups in stratified analyses by sex and age. An earlier study by the same research group noted no difference in uptake of HPV vaccine between 230 US female AYA survivors of cancer when compared with 70 age-matched controls with no previous history of cancer.⁵ Other studies also suggest low uptake of HPV vaccine among AYA survivors of cancer, but many either did not include comparison with healthy AYAs or examined intentions rather than behaviour. Cross-sectional studies of just AYA survivors of cancer have reported that male and younger (9–12 years compared with 13–17 years) respondents are less likely to receive HPV vaccine than are other AYA survivors of cancer.⁴

The Increasing Vaccination Model⁶ offers insights into effective approaches for promoting vaccine uptake, and is used by WHO and the US Centers for Disease Control and Prevention. The model's first proposition is that what people think and feel motivates vaccination. As with vaccine confidence in general, AYA survivors of cancer and their families have safety concerns that might undermine the uptake of HPV vaccine.⁷ Families might also see the threat of cancer as more pressing than prevention of other diseases later in life. A surprising finding is that efforts to change what people think and feel outside of clinical settings, such as through risk communication and confidence-boosting campaigns, are not reliably effective in increasing uptake.⁶

The model's second proposition is that social processes, including social norms and recommendations, motivate vaccination. AYA survivors of cancer face challenges such as absence of recommendations from primary care providers⁴ and ineffective communication when providers recommend the vaccine.⁷ Many caregivers also have not themselves received HPV vaccination, making the norm less salient. Efforts to leverage social processes are promising, especially through increasing the frequency and quality of provider recommendations.⁸ Opportunities include making HPV vaccination for AYA survivors of cancer a social norm, such as through advocacy by vaccinated AYA survivors of cancer,⁹ and encouraging more frequent and higher quality provider recommendations between ages 9 years and 12 years.⁹

The model's third proposition is that direct behaviour change increases vaccine uptake. The general idea is to help people to act on their willingness to vaccinate without trying to change what they think or feel or their social environment. Direct behaviour change interventions are the most reliably effective in increasing vaccine uptake. First, in-person reminders or reminders sent to patients via email or text message are relatively low cost and reliably effective at increasing uptake when coordinated centrally. Qualitative research suggests that AYA survivors of cancer would welcome reminders to complete the series of HPV vaccines, especially when accompanied by visual media.⁷ Second, ensuring easy access to vaccination is another reliably effective intervention. AYA survivors of cancer whose parents believe that they have inadequate health-care insurance coverage are less likely to receive HPV vaccine compared with parents who believe that they have adequate insurance coverage.⁴ For example, all US insurance plans already provide first dollar coverage for vaccination, and it is free to uninsured children through the Vaccines for Children programme. It is important to ensure that families know of these resources. Finally, automatic appointments, school-located vaccination, and cash incentives are also effective interventions that might be especially applicable to AYA survivors of cancer.

Low uptake of HPV vaccine among AYA survivors of cancer is worrisome given their high cancer risk and national recommendations for vaccination before age 13 years.² Risk of HPV exposure accelerates during adolescence, and the vaccines also generate the highest immune response when delivered at a young age. For these reasons, HPV vaccine is most effective when given at young ages, making vaccination of AYA survivors of cancer important. Clinicians and families might defer preventive services, including HPV vaccination, during cancer treatment. Additionally, many survivors of cancer are not fully reconnected to primary care once their treatment ends.¹⁰ Substantial opportunities exist for ensuring high uptake of HPV vaccine among AYA survivors of cancer. Improving engagement between cancer care and primary care teams is an important first step.

© 2022 Heather Hazzan/SELF Magazine/Flickr

NTB has served as a paid adviser for Merck Sharp and Dohme, the US Centers for Disease Control and Prevention, and WHO. All other authors declare no competing interests.