Although adolescent and young adult (AYA) survivors of cancer are at high risk for human papilloma virus infection (HPV), their vaccination rates are far lower that similarly aged individuals in the United States (US), according to an article appearing in the Journal of Clinical Oncology.
Vaccination against HPV has been recommended by the Centers for Disease Control and Prevention’s Advisory Committee on Immunization Practices for individuals in the overall population as early as 9 years of age until 26 years of age for females and 21 years of age for males. This cut-off age is extended to 26 in special subgroups, such as cancer survivors, due to the possibility that these persons may have treatment-related immunosuppression, placing them at elevated risk of HPV acquisition and disease, including persistence and sequelae, according to the authors.
James L. Klosky, director of psychological services and cancer survivorship, St. Jude Children’s Research Hospital in Memphis, USA and colleagues were prompted to assess the incidence of HPV vaccine in AYA cancer survivors as compared to age-matched individuals in the general US population who were identified in the National Immunization Survey-Teen and the National Health Interview Survey (2012-2015). Both cohorts were evaluated regarding socio-demographic and clinical characteristics, as well as age, gender, and vaccine-specific health beliefs.
This cross-sectional survey (NCT01492582) compared HPV vaccination rates in 982 cancer survivors aged 9 to 26 years of age who had been treated for cancer within the previous 1 to 5 years; 59% had been treated for leukaemia or lymphoma and 41% had solid tumours. The mean (standard deviation) time off treatment was 2.76 (±1.2) years. The participants’ mean age was 16.3 (±4.7) years, 55% were male, and 66% of participants were non-Hispanic white.
The primary endpoint of the study was self- or parent-reported HPV vaccine initiation, defined as the receipt of one or more HPV vaccine doses.
HPV vaccination lowest in adolescent cancer survivors
Vaccine initiation rates were significantly lower in cancer survivors compared to the aged-matched individuals in the general population; the rate of vaccination initiation was 23.8% (95% confidence interval [CI] 20.6%, 27.0%) compared to 40.5% (95% CI 40.2%, 40.7%; p < 0.001). AYA cancer survivors were more likely than their peers to be HPV vaccine–naive, odds ratio [OR] 1.72 (95% CI 1.41,2.09; p < 0.001).
Importantly, the vaccine initiation rate was the lowest and nearly half that of age-matched peers in adolescent survivors aged 13 to 17 years at 22.0% (95% CI 17.3%, 26.7%) versus 42.5% (95% CI 42.2%, 42.8%; p < 0.001). In this age group, the proportion of survivors actually receiving at least one, two, or three HPV vaccine doses compared to the general population was 23.8% versus 40.5%, 18.1% versus 29.1%, and 13.5% versus 20.8%, respectively (p < 0.001 for all comparisons).
HPV vaccine initiation was comparable, albeit low, between young adult survivors and their peers in the US aged 18 to 26 years at 25.3% versus 24.2%, respectively.
Demographic barriers figure into the low rates of vaccination in AYA cancer survivors
The foremost factor by multivariable logistic regression predicting for non-initiation of HPV vaccination was the lack recommendation by a healthcare provider, odds ratio [OR] 10.8 (95% CI 6.5, 18.0; p < 0.001).
Other factors that associated with lack of vaccination included the survivors’ perceived lack of insurance coverage for HPV vaccine, OR 6.6 (95% CI 3.9, 11.0; p < 0.001), male sex, OR 2.9 (95% CI 1.7, 4.8; p 0.001), endorsement of vaccine-related barriers, OR 2.7 (95% CI 1.6, 4.6; p < 0.001), and younger age ranging from 9 to 12 years, OR 3.7 (95% CI 1.8, 7.6; p < 0.001, as compared to 13 to 17 years).
In summary, just 24% of survivors initiated HPV vaccination and only 13.5% completed the three-dose series.
Regarding the endorsement of vaccine-related barriers, the authors pointed out that providers often favour vaccinating older adolescents. Furthermore, parental beliefs that their child is too young for vaccination are at odds with the fact that the maximum HPV vaccine benefit has been observed when administration is prior to sexual debut.
The authors pointed out limitations to this study, which was limited to survivors who were one to five years post-treatment. In addition, the study was confined to survivors followed in the United States. The investigators raised the concern that these findings are especially alarming when placed in the context of HPV vaccination rates in other developed countries. For example, the United Kingdom, Australia, Norway, Sweden, and Denmark, have achieved HPV vaccine initiation rates in the of approximately 80% and completion rates of 70% in targeted groups within the general population. The investigators noted that these countries have universal health care coverage and school-based HPV immunization programmes, which is in stark contrast to the United States, where universal health care coverage is not available and the lack of local school immunisation programmes may further contribute to low HPV vaccine uptake in the United States.
However, this is the first report, to the authors’ knowledge, to address HPV vaccine uptake among cancer survivors in any country, making the actual vaccine uptake among the vulnerable cancer survivor population in countries with high rates of HPV vaccination in the general population remaining unknown.