Defining a strategy to evaluate cervical cancer prevention and early detection in the era of HPV vaccination

Perceived Risk of Human Papillomavirus Infection and Cervical Cancer among Adolescent Women in Taiwan

PURPOSE

High-risk types of human papillomavirus (HPV) are a critical etiologic factor behind cervical cancer. Adolescents are a vulnerable group for HPV infection. However, the literature on adolescent women for HPV infection and cervical cancer is limited. This study was to investigate HPV-related knowledge and perceived risk of HPV infection and cervical cancer among Taiwanese adolescent women in order to assess intervention strategies for prevention of cervical cancer and maintenance of reproductive health.

METHODS

A descriptive cross-sectional study design was implemented. There were 610 adolescent women from three colleges in Southern Taiwan who participated in this study. Data were collected using an anonymous self-administered questionnaire survey.

RESULTS

The results showed that the percentage of appropriate answers to HPV-related knowledge questions was only 36.8%, and smoking as the leading cause of cervical cancer received the lowest mean score for appropriate answers among the HPV-related knowledge items. The perceived risk of HPV infection and cervical cancer were moderate, with relatively lower susceptibility to infection with HPV than to cervical cancer (p < .001). Only 11.5% of the participants reported that they had received information about HPV vaccination from healthcare professionals.

CONCLUSIONS

Participants lacked a comprehensive understanding of cervical cancer prevention and were not aware of their susceptibility to HPV infection. Adolescent women rarely obtained HPV-related information from healthcare professionals. Appropriate education strategies should be developed and conducted by healthcare professionals to reduce the risk of cervical cancer threat from adolescence.

Optimizing technology for cervical cancer screening in high-resource settings

Although historically successful in reducing the burden of cervical cancer, Papanicolaou (Pap) testing faces numerous limitations. A growing body of evidence suggests that modern screening practice will benefit from primary screening for high-risk human papillomavirus (HPV) infection, the causative agent of cervical cancer. Molecular tests detecting the presence of HPV nucleic acids consistently demonstrate high sensitivity relative to Pap testing, and provide reliable, dichotomous results. Pap cytology is ideally suited to triage HPV-positive cases owing to its high test specificity, and the accuracy of cytological readings will be maximized in high-prevalence conditions. This algorithm of primary HPV testing with Pap triage has been shown to maintain the high sensitivity of HPV testing without compromising Pap cytology's strong ability to rule out falsely positive diagnoses. Given the anticipated decline of high-risk HPV-16 and -18 infections in the emergent post-HPV vaccination era, highly sensitive primary HPV testing is especially warranted. Novel screening technologies that identify HPV viral gene expression continue to emerge and seek to complement current HPV testing by identifying those women who may be at risk of progressive disease. How to best incorporate these new technologies into clinical practice presents our next great challenge. Implementation of novel algorithms for cervical screening is not a trivial task. Avoidance of exceedingly complex screening algorithms is an important priority.

Invasive and in situ cervical cancer reported to the vaccine adverse event reporting system (VAERS)

The quadrivalent human papillomavirus (HPV) vaccine was recommended in 2006 for routine vaccination of 11 or 12-year-old girls, with catchup through age 26 years, for the prevention of genital HPV-related diseases. The Vaccine Adverse Event Reporting System (VAERS) is a national spontaneous surveillance system of adverse events following vaccination in the United States. The objective of this study was to identify and review VAERS reports of invasive and in situ cervical cancer in women immunized with the quadrivalent HPV vaccine. A VAERS database search was performed to identify such cases reported in the United States from January 1, 2006, through April 9, 2009. Medical Dictionary for Regulatory Activities (MedDRA) search terms used were "cervix carcinoma," "cervix carcinoma stage 0," "cervix carcinoma stage III," "carcinoma in situ," and "cervical dysplasia." Case inclusion required a report to contain a clear statement of a cervical carcinoma or carcinoma in situ diagnosis on any screening or diagnostic test after at least one dose of the HPV vaccine. All reports were reviewed by two investigators. Four VAERS reports for MedDRA term "cervix carcinoma," one for "cervix carcinoma stage 0," none for "cervix carcinoma stage III," three for "carcinoma in situ," and 53 for "cervical dysplasia" were identified. Of these, three cases of carcinoma in situ and one case of microinvasive cervical cancer met study inclusion criteria. Cases of cervical cancer and precancers are not unexpected in vaccinated women. Cervical cancer screening continues to be important, even for women who have received the HPV vaccine.

Canadian oncogenic human papillomavirus cervical infection prevalence: systematic review and meta-analysis

BACKGROUND

Oncogenic human papillomavirus (HPV) infection prevalence is required to determine optimal vaccination strategies. We systematically reviewed the prevalence of oncogenic cervical HPV infection among Canadian females prior to immunization.

METHODS

We included studies reporting DNA-confirmed oncogenic HPV prevalence estimates among Canadian females identified through searching electronic databases (e.g., MEDLINE) and public health websites. Two independent reviewers screened literature results, abstracted data and appraised study quality. Prevalence estimates were meta-analyzed among routine screening populations, HPV-positive, and by cytology/histology results.

RESULTS

Thirty studies plus 21 companion reports were included after screening 837 citations and 120 full-text articles. Many of the studies did not address non-response bias (74%) or use a representative sampling strategy (53%). Age-specific prevalence was highest among females aged < 20 years and slowly declined with increasing age. Across all populations, the highest prevalence estimates from the meta-analyses were observed for HPV types 16 (routine screening populations, 8 studies: 8.6% [95% confidence interval 6.5-10.7%]; HPV-infected, 9 studies: 43.5% [28.7-58.2%]; confirmed cervical cancer, 3 studies: 48.8% [34.0-63.6%]) and 18 (routine screening populations, 8 studies: 3.3% [1.5-5.1%]; HPV-infected, 9 studies: 13.6% [6.1-21.1%], confirmed cervical cancer, 4 studies: 17.1% [6.4-27.9%].

CONCLUSION

Our results support vaccinating females < 20 years of age, along with targeted vaccination of some groups (e.g., under-screened populations). The highest prevalence occurred among HPV types 16 and 18, contributing a combined cervical cancer prevalence of 65.9%. Further cancer protection is expected from cross-protection of non-vaccine HPV types. Poor study quality and heterogeneity suggests that high-quality studies are needed.

Global challenges of implementing human papillomavirus vaccines

Human Papillomavirus vaccines are widely hailed as a sweeping pharmaceutical innovation for the universal benefit of all women. The implementation of the vaccines, however, is far from universal or equitable. Socio-economically marginalized women in emerging and developing, and many advanced economies alike, suffer a disproportionately large burden of cervical cancer. Despite the marketing of Human Papillomavirus vaccines as the solution to cervical cancer, the market authorization (licensing) of the vaccines has not translated into universal equitable access. Vaccine implementation for vulnerable girls and women faces multiple barriers that include high vaccine costs, inadequate delivery infrastructure, and lack of community engagement to generate awareness about cervical cancer and early screening tools. For Human Papillomavirus vaccines to work as a public health solution, the quality-assured delivery of cheaper vaccines must be integrated with strengthened capacity for community-based health education and screening.