A potential vaccine against the virus that causes cervical cancer and genital warts protects nine out of ten women, according to research published online by The Lancet Oncology yesterday (7 April).
Scientists found that the vaccine protected women against human papillomavirus types 16 and 18, which together cause about 70 per cent of cervical cancer, and types 6 and 11, which cause 90 per cent of genital warts.
The researchers tested the vaccine on 552 healthy women, aged 16-23, from Brazil, Europe and the United States. Half were given the vaccine and half were given a placebo.
During the trial, the women had regular cervical smears to identify potentially cancerous cells, and were tested for the presence of viral DNA.
The virus infects nearly 70 per cent of sexually active women worldwide at some point in their life. Although screening reduces the number of women who develop cervical cancer, pre-cancerous lesions need close monitoring and often have to be removed.
Most cases of cervical cancer (80 per cent of the estimated 370,000 new cases per year) arise in the developing world where cancer-screening programmes are rare.
Luisa Lina Villa of the Lugwig Institute for Cancer Research, Sao Paulo, Brazil, lead author on the article, says a vaccine could greatly reduce the incidence of cervical cancer in developing countries.
A vaccine would ideally be given to 10-13 year-old girls, who are unlikely to be sexually active and thus have probably not been exposed to the virus.
The researchers do not know how long their vaccine would protect those who are given it. But they stress that because women are at risk of human papillomavirus infection for as long as they are sexually active, protection induced by a vaccine must be long-lived.
The researchers add that a vaccine such as theirs, which protects against genital warts, could protect men as well as women.
Large-scale trials of the vaccine are underway.
Reference: Lancet Oncology (2005) DOI 10.1016/S1470-2045(05)70101-7