Cervical cancer is one of the most common cancers in women worldwide, and known as a preventable cancer threatening female health.1,2) Cervical cancer is not only the leading cause of death among middle-aged women worldwide, but also contributes about fifty percent of the world's total cervical cancer cases in Asia Pacific region.3)

Human papillomavirus (HPV), one of the most common sexually transmitted infections, is related to almost all cervical cancers.4) HPV infection is temporary and asymptomatic, and it is resolved naturally with no treatment. However, some high-risk cases of HPV infection could develop chronically and become a cause of cervical cancer. Out of more than 100 types of HPVs, HPV-16 and HPV-18 are the most common high-risk genotypes, and are accountable for 70% of cervical cancers.3-5) Therefore, controlling HPV infection is crucial to prevent sexually transmitted diseases (STDs) and cervical cancer for women's health.

There have been two prophylactic HPV vaccines available in many countries since 2006, including Gardasil®, as a quadrivalent vaccine, and Cervarix™, as a bivalent vaccine.4,6) Gardasil® was approved by the US Food and Drug Administration (FDA) in 20066), and in South Korea, both Gardasil and Cervarix have been available since 2007. The Com-mittee on Infectious Disease of the Korean Pediatric Society and the Korean Society of Gynecologic Oncology and Colposcopy recommended the immunization for Korean women, and their guidelines proposed over 15 yr of age as appropriate for vaccination considering the first sexual intercourse of Korean girls.7,8)

Research has indicated that about 30-60% of sexually active adults are infected by HPV at some point in their lives,5) and young adults are especially at risk of high prevalence of HPV infection.2) Despite the effects and importance of HPV vaccination in preventing cervical cancer, wo-men's knowledge of HPV vaccine and its uptake have been reported low worldwide.2,9) In addition, statistics in Western countries reported that about 37-50% of adolescent had limited knowledge level about HPV and HPV vaccine.2,10,11) Little is known about young women's knowledge of HPV in the South-East Asia region.2)

Recommendations for HPV vaccination vary across countries, but the general vaccine programs target girls and young women between ages of 9 and 19 yr.12) Currently there are no clinical contraindications against vaccinating women older than the recommended age,13) and clinical trial data demonstrated that HPV vaccine is safe and effective in older women up to the age of 55 yr.12)

Across studies conducted in the west, HPV vaccination acceptability was relatively positive. However, this could be different in Asian countries since cultural belief, family and social norm toward STDs and its prevention are different.14-16) The purpose of this review is to provide a summary of findings from studies of attitudes and knowledge about HPV and HPV vaccination, and actual uptake studies that have been performed in Asian countries.

The author mainly searched the Pubmed, Cumulative Index to Nursing and Allied Health Literature (CINAHL), and Korean Information Service System (KISS) electronic databases to identify peer-reviewed articles published between 2006 and 2011. Broad search terms such as "HPV vaccines," "attitude or knowledge," and "Asia" were used to obtain the largest amount of HPV literature available.

The inclusion criteria for literature search included published articles written in English and Korean, and online access to the full text. Because the HPV vaccine was approved in the U.S. after 2006 and has been available since 2007 in South Korea, the search was limited to articles that have been published since 2006. The search was limited to studies with female participants. The title and abstracts were also reviewed to identify studies that met the inclusion criteria. An exhaustive database search and reference checking resulted in the identification of 17 published studies. Each of the articles was evaluated according to the following review po-ints: (a) women's knowledge of HPV and HPV vaccination; (b) attitudes toward HPV vaccination; and (c) actual uptake of HPV vaccines.

The selected articles (Table 1) represent seven Asian countries; Hong Kong, Malaysia, China, India, Korea, Taiwan, and Thailand. Among these studies, 4 of 17 studies were searched in KISS and written by Koreans. Most studies used retrospective cohort design and included quantitative (n=13) and qualitative (n=4) methodology; a majority of the studies employed convenience sampling. All of the quantitative studies were cross-sectional, with sample sizes ranging from 189 to 8008. Three qualitative studies entailed focus group discussion and one employed an in-depth interview; their sample sizes ranged from 25 to 49.

Five studies performed primary recruitments from universities.2,17-20) Most studies measured knowledge of HPV related issues and awareness or attitudes toward HPV vaccination for adult women. One study was compared the knowledge level of clinical nurses who received HPV vaccine and those who did not, and their perception of relationship between HPV vaccination and cervical cancer.21) Hsu et al. (2010) explored reasons that young adults and older women were vaccinated against HPV.22)

The literature review was conducted in order to understand and analyze recent studies regarding the level of knowledge about HPV related conditions, attitudes toward HPV vaccine, and actual uptake of HPV vaccines among women Asian countries. In the findings, issues regarding low level of knowledge and awareness of HPV vaccine and cultural barriers of HPV vaccination were discussed.

The studies included in this review indicated a general lack of knowledge about HPV and HPV vaccine among Asian adult women. However, knowledge deficit about HPV is not the only issue for adult women in Asian countries. Other studies in Western countries, relatively well developed society, also showed similar deficiency in knowledge of HPV.29) Since the lack of knowledge could be one of the barriers for acceptance of HPV vaccine, the findings from existing research imply that there is an immediate and aggressive need for public education on HPV and its vaccines.

The concept and measurement of knowledge within this review was limited. Across studies, the concept of knowledge and knowledge level were ambiguous, and the wording of knowledge in HPV was used interchangeably to awareness of HPV. For example, some studies measured participant knowledge by asking the participants whether they had heard of HPV and HPV vaccine, while others quantified the level of knowledge scoring the correct answers of test-based questionnaires. Even though the measurement tool for assessing knowledge was different from investigat-ing participant awareness of the disease, many researchers interchangeably used these concepts as the same one. This may not only cause confusion among researchers but may also limit the comparability of the studies. Developing standardized test-based questionnaires seems crucial to measure the baseline knowledge of HPV and monitor changes in subject knowledge after participating in educational and intervention program.

Despite the low level of knowledge and awareness about HPV and HPV vaccines, studies reported relatively high and positive attitudes toward HPV vaccination among adult women. Concerns about HPV infection, genital warts, fear of cervical cancer, and clinician's recommendations were the main reasons for women to have a positive intention for vaccination. Along with positive intention, the reasons for their unwillingness for vaccination were also reported. In most cases, concerns about side effect and safety issues were identified as major barriers. Because of the STD nature of HPV infection, several studies discussed social stigma to receive STD vaccines and HPV vaccination could be the cultural barrier in Asian countries. Participants' belief and perception that proper or normal sexual relationship with a regular partner would not need HPV vaccination could be a critical cultural barrier among Asian women. Such negative attitude toward HPV vaccines may not only influence their own decisions, but also may have an effect on HPV awareness of their daughters and sons. Moral stigmatization issues surrounding HPV vaccination should be more actively discussed among policy makers and health care providers to increase the vaccine uptake in Asian countries.

Similar to studies in Western countries, high cost of vaccination was identified as a critical barrier for HPV vaccination.30) HPV vaccination costs approximately US $360,28) making it unaffordable for many women. Even though many participants showed positive intention for the vaccination, high cost was identified as one of the main reasons for the low access to the preventive behaviors. As many studies recommended, governments may need to subsidize vaccines or include HPV vaccine as universal mass vaccination for public to increase access to the vaccination.18,26,28) Along with educational program to increase knowledge of HPV and HPV vaccination, such efforts to reduce financial burden for vaccination could increase the rate of HPV uptake in Asian countries.

In conclusion, findings from this review indicate that adult women in Asian countries are in an urgent need of improvement of HPV and HPV knowledge. Despite the low knowledge level of HPV and awareness of HPV vaccination, the studies included in this review reveal that HPV vaccine acceptance is high among adult women in Asian countries. The studies identified several factors that may have resulted in positive and negative intent to receive the HPV vaccines. A sense of fear of cervical cancer, genital warts, STDs, and health care provider's recommendation are possible facilitators for the acceptance of HPV vaccines among Asian adult women. On the other hand, concerns about safety and efficacy of new vaccines, high cost for vaccination, social stigmatization of the nature of STD vaccines, and perception of HPV as not being a serious risk were discussed as potential reasons for the negative attitude towards STD.

Health care providers and nurses should focus on the need of education based on these findings. Since nurses take responsibility for providing information and education on health related issues, their duty and role are important to increase knowledge on HPV and HPV vaccinations within their communities. Nurses in clinical settings, schools, and community should include education program and campaign about HPV knowledge and its vaccine to increase vaccine uptake and prevent cervical cancer. Future nursing research is needed to explore cultural facilitators and barriers for vaccination. Further policy makers, health care providers, and public health educators should also be aware of cultural barriers and attitudes toward HPV vaccination in developing and implementing educational program and interventions for adult women in Asian countries.