Virus-blocking vaccine offers cervical cancer hope

By MARTIN JOHNSTON and REUTERS

A new vaccine to protect against a virus linked to cervical cancer has proved extremely effective in a trial involving more than 2000 young women.

The vaccine, given in three injections, is designed to block infection by human papillomavirus (HPV) type 16.

None of the 1194 sexually active women who were given the vaccine in the American study developed a persistent infection from the virus.

But 3.8 per cent of the 1198 women who were given placebo injections did become infected, said the research team, led from the University of Washington.

Their results were published in the New England Journal of Medicine.

Dr Christopher Crum, of Brigham and Women's Hospital in Boston, said the vaccine could radically reduce the risk of cervical cancer.

Since HPV types 16 and 18 were responsible for the deadliest tumours, a vaccine against them would probably slash the death rate from cervical cancer by 95 per cent, he said in an editorial in the journal.

The vaccine is made by drug company Merck, which paid for the study.

Merck has started an international trial involving that vaccine and another version targeting four strains of HPV: types 16, 18, 11 and 6.

Genetic material from HPV, a common sexually transmitted infection, is found in virtually all cases of cervical cancer. But experts believe other factors such as cigarette smoking or a weakened immune system must also be present for HPV to progress to cancer.

HPV type 16 is thought to be responsible for about 50 per cent of all cases of cervical cancer and type 18 for a further 20 per cent.

The international trial will involve 5700 young women, including 300 in New Zealand. The participants will be randomly assigned to receive one or other of the vaccines or placebo injections.

Merck spokesman Phil Johnstone said yesterday that 56 women had been recruited so far for the New Zealand portion of the trial.

Cervical cancer appears in 450,000 women worldwide each year, causing about 250,000 deaths.

Around 200 New Zealanders are diagnosed with cervical cancer every year, and the disease kills about 80.

Cancer Society of New Zealand spokeswoman Betsy Marshall said mass vaccination would be an important means of controlling the disease in future.

"But it's unlikely in the short-term to address cervical cancer in total.

"Screening [smear tests and treatment of any abnormalities] will still be a very important part of controlling cervical cancer."

Other manufacturers are testing vaccines that protect against HPV 16 and other cancer-causing strains as well - types 18, 31, 33 and 45. But some doctors said the Merck product held the most promise.

"There are several papilloma vaccines but this is the only one that seems to have really got anywhere," said Dr Anne Szarewski, a clinical consultant at Cancer Research UK.

"Given that this vaccine has done so well in its Phase II trials, it's looking pretty positive ...

"In theory this could be on the market within five years."

Herald feature: Health