Strains identified for cervical cancer human papillomavirus vaccine
Researchers have identified strains of human papillomavirus (HPV) that could be used to prevent up to 84 per cent of cervical cancer cases, participants at the recent European Cancer Conference in Copenhagen heard.
Dr Xavier Bosch, Institut Catala d’Oncologia, Barcelona, explained
that persistent infection with high-risk types of HPV increases the risk
of cervical cancer. These types are detected in 90–100 per cent
of cases, as opposed to 5–20 per cent of controls. Their role in
the cause of cervical cancer provides a strong rationale for their use
in screening and for the development of anti-HPV vaccines.
Dr Bosch studied a pool of evidence on HPV and cervical cancer collected
by the International Agency for Research on Cancer based in Lyon, France.
His group estimated that a vaccine including HPV 16 and 18, the most
common high-risk types of the virus, would prevent 72 per cent of cervical
cancer cases among those vaccinated in Europe and North America. A vaccine
containing types 16, 18, 33, 31 and 45 would cover 84 per cent of cases,
he added.
Dr Bosch reported that, in Europe, around 65,000 new cases of cervical
cancer are diagnosed each year, of which 21,000 eventually lead to death. “HPV
vaccinations are still in the experimental stage, and the vaccine would
be expensive at introduction. But the gains in the longer term would
be huge both in terms of health care costs and in women’s quality
of life,” Dr Bosch said.
Meanwhile, a Cancer Research UK project has found that a vaccine against
HPV 16 and 18 acts against a pre-cancerous disease of the vulva. Scientists
at the charity’s Paterson Institute, Manchester, in collaboration
with doctors at St Mary’s Hospital, tested a vaccine called TA-HPV,
which was developed by Xenova Research Ltd and is a modified version
of the smallpox vaccine.
They gave the vaccine to 18 women with vulval intraepithelial neoplasia
(VIN) — a condition in which precancerous lesions appear on the
lining of the vulva and are difficult to treat.
Thirteen women developed a specific immune reaction to HPV and, in eight,
the diameter of the lesion shrunk by at least 50 per cent. This is the
first time scientists have used vaccines of this type in women with VIN.
Lead researcher Professor Peter Stern of Cancer Research UK said: “Our
results were encouraging ... although I think vaccines will prove most
useful as part of a combination of treatments.” He added that the
vaccines appeared well tolerated, with less impact than one of the current
mainstays of treatment — surgery. It appeared that the vaccine
was more effective in women with high levels of immune cells in their
lesions before vaccination.
“It could be that we will need to test women beforehand, to identify
a group who are most likely to benefit from vaccination. It is also possible
that repeated vaccination may build up the immune response against cancer,
in which case it might be necessary to give women a number of shots of
vaccine during a course of treatment,” Professor Stern added. |
