Another cervical cancer vaccine-Cervarix, developed by GlaxoSmithKline-has demonstrated positive results in a recent trial. The vaccine was found to still be effective after nearly five years, and may protect women against more types of cancer-causing viruses than originally thought, researchers report.
A specific type of infectious pathogen, called the human papillomavirus (HPY), causes most cervical cancers. Cervarix is designed to protect against HPV 16 and HPV 18, which account for approximately 70% of cervical malignancies, Harper says.
This study is a follow-up on some of the women who participated in a previous study that measured the effectiveness of the Cervarix vaccine.
Study author Dr. Diane M. Harper, a professor of community and family medicine and obstetrics and gynecology at Dartmouth Medical School, and her team tracked 776 of these women for up to 53 months. The women had received either three doses of the vaccine or three doses of placebo.
The researchers found that not only did the vaccine provide protection against HPV 16 and HPV 18, but also against two other HPV types HPV 45 and HPV 31, which can also trigger cervical cancer.
After 4.5 years, all of the women still tested positive for having been immunized with HPV 16 and HPV 18.
And, Harper notes, "Their antibody levels [which develop after a vaccine is administered], on average, did not decrease," indicating that the vaccine was still working and offering ongoing protection against these cancer-causing viruses.
The vaccine's apparent long-term effectiveness is promising, says Rachel Winer, a research scientist and HPV researcher at the University of Washington, Seattle.
Once a cervical cancer vaccine hits the market, young women in their late teens or early 20s would be the most likely candidates to receive it, she says.
The multistrain cross-protection that Cervarix offers is a bonus, 'Winer adds, and "worth investigating further" to find out the mechanism behind it.