Human papillomavirus and cervical cancer in the Pacific
BY: Callum Narita, Editorials and Publications Team PMSA
Human papillomavirus (HPV) is a highly prevalent DNA virus that is spread through physical contact. It is one of the most common sexually transmitted infections globally (1), with an estimated 291 million women across the world carrying the virus. The infection itself can be asymptomatic, however often results in warts in the area affected. Importantly, HPV can lead to the development of precancerous growths, primarily of the cervix, which can in turn develop into cancer. These HPV-related growths are the cause for the clear majority of cervical cancers.
Various strains of HPV are present throughout the world (1). Two strains, 16 and 18, account for a significant proportion of cancers caused by HPV (2). A vaccine for the virus is commonly given to children in Australia and developed nations, primarily targeting only those strains commonly found to cause cancer (3). Avoiding infection essentially eliminates the risk of the cancer occurring, reducing the burden of disease as well as the requirements for screening.
In Pacific Island Countries and Territories, the statistics are concerning. There is a high prevalence of cervical cancer, and a high mortality rate as a result. Fiji has an estimated yearly incidence of 56 cases per 100,000 for cervical cancer in indigenous Fijian women, resulting in a 32.9 per 100,000 mortality rate (4). Estimates for the entire Pacific region are similar, and these rates are significantly higher than other regions across the globe (5).
Additionally, it appears that the cancer-causing strain prevalence in the Pacific may be vastly different to the rest of the world (6). Strains 16 and 18 only cover approximately 28% of the cancers detected. Further, these patients appear to present with more advanced disease than elsewhere, which can lead to worse outcomes.
Why is this important? The coverage of the more common vaccine, which targets the two most prevalence cancer causing strains of HPV, would only have a small impact in the region. However, a newer vaccine has been produced, which has a significantly broader coverage of HPV strains (7). This vaccine could greatly reduce the impact of HPV and cervical cancer on the health and mortality of those in the Pacific region. However, it is likely to be expensive to distribute as it is best given to an entire population.
1. De Sanjosé S, Diaz M, Castellsagué X, Clifford G, Bruni L, Muñoz N, et al. Worldwide prevalence and genotype distribution of cervical human papillomavirus DNA in women with normal cytology: a meta-analysis. The Lancet infectious diseases. 2007;7(7):453-9.
2. Khan MJ, Castle PE, Lorincz AT, Wacholder S, Sherman M, Scott DR, et al. The elevated 10-year risk of cervical precancer and cancer in women with human papillomavirus (HPV) type 16 or 18 and the possible utility of type-specific HPV testing in clinical practice. J Natl Cancer Inst. 2005;97(14):1072-9.
3. Garland SM, Hernandez-Avila M, Wheeler CM, Perez G, Harper DM, Leodolter S, et al. Quadrivalent vaccine against human papillomavirus to prevent anogenital diseases. N Engl J Med. 2007;356(19):1928-43.
4. Vodonaivalu L, Bullen C. Trends in cervical cancer in Fiji, 2000–2010. Public health action. 2013;3(1):68-71.
5. Ferlay J, Shin HR, Bray F, Forman D, Mathers C, Parkin DM. Estimates of worldwide burden of cancer in 2008: GLOBOCAN 2008. Int J Cancer. 2010;127(12):2893-917.
6. Schisler T, Bhavsar A, Whitcomb B, Freeman J, Washington M, Blythe J, et al. Human papillomavirus genotypes in Pacific Islander cervical cancer patients. Gynecologic oncology reports. 2018;24:83-6.
7. Petrosky E, Bocchini JJ, Hariri S, Chesson H, Curtis CR, Saraiya M, et al. Use of 9-valent human papillomavirus (HPV) vaccine: updated HPV vaccination recommendations of the advisory committee on immunization practices. MMWR Morbidity and mortality weekly report. 2015;64(11):300-4.