Against which human papillomavirus types shall we vaccinate and screen? the international perspective

Abstract

At least 15 types of HPV have been associated with cervical cancer, but current HPV vaccines confer only type-specific immunity. To determine geographic variations in the HPV type distribution in cervical cancer, we carried out a pooled analysis of data from an international survey of HPV types in cervical cancer and from a multicenter case-control study, both co-coordinated by the IARC. Study cases were 3,607 women with incident, histologically confirmed cervical cancer recruited in 25 countries. HPV DNA detection and typing in cervical cells or biopsies were centrally done using PCR assays. Estimates of the potential number of cases prevented by HPV type-specific vaccines and changes in the validity of different HPV screening cocktails were calculated. HPV DNA was detected in 96% of specimens, and 30 different types were detected. Key words: cervical cancer; human papillomavirus; human papillomavirus geographic distributionCervical cancer is the second most common cancer in women worldwide but the first in most developing countries, where 80% of cases occur. 1 Molecular epidemiologic evidence accumulated over the past 20 years clearly indicates that certain HPV types are the central and probably necessary cause of cervical cancer. [2][3][4] Over 100 HPV types have been identified, and about 40 are known to infect the genital tract. 5 To assess the geographic distribution of HPV types in invasive cervical cancer and the risk linked to the various HPV types, the IARC carried out an international survey of cervical cancer specimens in 22 countries 4,6 and a multicenter case-control study in 11 countries around the world. [7][8][9][10][11][12][13][14][15] These studies were carried out using the same protocol and sensitive PCR assays for the detection of HPV DNA in a central laboratory.HPV prophylactic vaccines for the most common types (HPVs 16 and 18) are now being tested in various populations with promising results as they have been shown to be safe and to induce high titers of neutralizing antibodies that prevent HPV infection and cervical intraepithelial neoplasia (CIN). 16 -18 Although there is some evidence of cross-reactivity among certain HPV types, 19 this appears to account for Ͻ1% of antibody reactivity, indicating that protection to infection is type-specific. Effective HPV vaccines should then be polyvalent and should contain the HPV types responsible for most cervical cancers. It is thus of great importance to assess if there are significant differences in the geographic distribution of HPV types causing cervical cancer. If this is the case, their description would provide the rationale for considering tailoring vaccine products to the HPV types prevalent in a given geographic area vs. producing a common vaccine suitable to the worldwide distribution of HPV types. Previous studies have revealed some geographic differences in HPV type distribution, but the size of individual studies and the validity of the PCR testing systems used precluded delineation of clear patterns. 4,6 -15,20 HPV screening...

Human papillomavirus genotype distribution and cervical squamous intraepithelial lesions among high-risk women with and without HIV-1 infection in Burkina Faso

“…Therefore, administration of a bivalent HPV-16/18 vaccine in this population before they get exposed might have the potential to prevent the majority of highgrade lesions in this population, but this would need to be determined in prospective studies. It is not known, however, whether successful control of HPV-16 or -18 might not lead to replacement by other oncogenic HPV types, which are highly prevalent in our population as in many parts of sub-Saharan Africa (Muñoz et al, 2004).…”

Routine cervical screening with primary HPV testing and cytology triage protocol in a randomised setting

“…On the area of cervical cancer prevention, much emphasis and hope has lately been given on human papillomavirus (HPV) vaccines being tested around the world (Koutsky et al, 2002;Harper et al, 2004;Munoz et al, 2004). Nevertheless, organised population-based screening is still the most effective way to control for cervical cancer (The working group of IARC, 2005).…”

Prevention of cancer through immunization: Prospects and challenges for the 21st century

“…Ongoing epidemiological studies have shown that infection of the genital tract with HPV is very common, with over 50% of sexually active young women and young men acquiring at least one genital HPV infection in the first 5 years of sexual activity [9]. Cervical cancer is causally associated with infection by one of a subset of about 15 genital HPV termed "high-risk" [10]. Worldwide, two of the high-risk HPV types, HPV16 and 18, are responsible for approximately 70% of cervical cancer and are also the HPV types most often found in HPV-associated cancers at other sites.…”