Gardasil in the Developing World
Researchers at the University of Queensland Diamantina Institute have confirmed through a study in Vanuatu that a test for human papilloma virus (HPV) could help control cervical cancer in developing countries.
Early detection has proven essential in controlling cervical cancer risk in developed countries where screening programs have reduced the prevalence of the disease by about 75%. Yet cervical cancer remains the second most common cancer in women and causes approximately 275,000 deaths worldwide each year. Due to severely limited access to adequate screening, the brunt of this mortality will be borne by women in developing countries where more than 80% of new cases occur each year.
Nearly all cervical cancer is caused by a persistent HPV infection, which causes abnormal growth in the cells lining the cervix. Ideally, women will undergo a regular ‘cytology’ screen, or Pap test, where a cell sample is assessed by a trained pathologist. Any pre-cancerous or cancerous tissue is then removed. The earlier the disease progression is detected, the higher the chance for survival. Although effective, large scale cytology screening programs require substantial resources in terms of medical expertise and infrastructure. As such, they are simply not feasible in resource-poor settings. The recent development of an HPV vaccine shows great promise for controlling the prevalence of the disease. However, UQ Professor Ian Frazer, the vaccine’s co-creator, explains that many women in developing countries continue to have little or no access to the vaccine and millions have already been exposed to the virus.
Studies have shown that in women over 30, testing positive for HPV is indicative of the kind of persistent infection that leads to cervical cancer. Consequently, numerous global health experts believe an HPV-test could provide a viable screening alternative in developing countries. However, it is under debate as to whether a positive HPV-test would be a sufficiently specific indicator of cervical cancer risk. Moreover, a clearer picture of both HPV and cervical cancer prevalence in these regions is also needed.
Led by Professor Frazer and Dr Margaret McAdam, researchers at the UQ Diamantina Institute have worked with the Vanuatu Ministry of Health to conduct a pilot study in Vanuatu, evaluating cervical cancer screening and treatment strategies in a low resource setting. This study also represents the first in depth look into the prevalence of cervical cancer in Vanuatu. In collaboration with Ni-Vanuatu health care professionals, they recruited approximately 1000 apparently healthy women between the ages of 30 and 50 who were assessed for cervical cancer risk using both standard methods as well as an HPV test.
The study, which was published online this month in PLoS one, revealed a cervical cancer prevalence estimate of 100 in 100,000, amongst the highest in the world. The study went on to show that, as expected, cytology screening effectively detected the presence of pre-cancerous cervical cells. However, the HPV-test proved to be a more sensitive indicator of cervical cancer risk, and, critically, showed higher specificity than some of the simpler tests that have been proposed. As a result of their findings, the researchers propose that — for women over 30 — a single locally-conducted HPV test in combination with appropriate treatment for women with a positive test could provide an effective means of reducing the cervical cancer burden in developing countries.