London: A vaccine against two strains of the human papillomavirus (HPV) could cut the number of cases and deaths from cervical cancer by three-quarters in the UK, according to a new study.[i]
The study, sponsored by pharmaceutical company GlaxoSmithKline (GSK), was presented at the International Papillomavirus Conference in Prague (September 1-7 2006).
It found that with 100% coverage, the vaccine could lead to a 76% reduction in cases of cervical cancer and a similar reduction 76% – in deaths from the cancer.
The researchers assumed that the women vaccinated would take part in the UKs existing cervical screening programme, so the benefits of vaccination highlighted in the study are in addition to the lives already being saved by cervical smears.
A computer model was used to predict the outcome of vaccinating all 12-year-old girls in the United Kingdom (376,385 girls) over their lifetime.
Extrapolating the decrease in cervical cancer cases and deaths seen in the study across the entire UK population, using the latest UK figures, would mean 262 women dying each year from cervical cancer, where currently there are 1,093 deaths.[ii] The number of cases of the disease in the UK would also drop from 2,841 to 682.[iii]
The researchers admit that 100% coverage assumed in the study is unrealistic, so the computer model gives alternatives. With 80% of 12 year old girls vaccinated, cancer cases and deaths are predicted to drop by around 61%.
The study also examined the potential impact of vaccination on the precancerous stages of cervical disease.
Over the lifetime of women vaccinated at 12 years of age, vaccination is predicted to reduce the burden of abnormal smears due to cancer-causing HPV by over half (52.4%) and the subsequent need for diagnostic colposcopies by 54.8%.
Vaccination is also predicted to bring a 70% reduction in the more severe pre-cancerous stages of cervical disease due to cancer-causing HPV strains (known as Cervical Intraepithelial Neoplasia, CIN 2 and 3).
This research examined the long-term impact of HPV vaccination using GSKs candidate HPV vaccine which targets HPV 16 and 18, the two most common HPV strains associated with cervical cancer.
Protection against additional cancer-causing strains of HPV was also included in the model.
This inclusion was based on preliminary evidence from GSK clinical trials, showing that the candidate HPV vaccine demonstrates additional protection against infection with the third and fourth most common HPV strains associated with cervical cancer globally, HPV 45 and 31.[iv]
The public health benefits of vaccination may be greater than predicted by the study since it does not look at cancers caused by HPV that affect other parts of the body.
There is evidence that HPV 16 and 18 may play a role in causing other anogenital cancers, including vulval and vaginal cancers. Therefore, in theory, protecting the body against cervical cancer could also prevent these additional cancers.
Further research is now being carried out to look at the overall cost-effectiveness of HPV vaccination to the NHS, which currently spends £157 million a year in England alone on the cervical cancer screening programme.[v]
Dr Anne Szarewski, Clinical Consultant for Cancer Research UK, who researches into HPV, said: HPV vaccination offers great promise in terms of reducing the number of cases of cervical cancer and preventing deaths from it.
Currently there are still 3,000 women in the UK who get cervical cancer each year despite a highly efficient screening programme.
The peak age for cervical cancer to strike is while women are in their late-30s, but it can occur earlier. Treatments, such as hysterectomy, will prevent them having children, perhaps before they have had a chance to start a family.
Dr Szarewski added: Beyond the cases and the deaths, hundreds of thousands of women each year in the UK suffer anxiety when they have an abnormal smear result. The idea of finally being able to prevent cases of cervical cancer with a vaccine is extremely exciting.
About GSKs candidate HPV vaccine
GSKs HPV vaccine targets HPV strains 16 and 18. In clinical trials, it has demonstrated sustained efficacy up to 4.5 years against HPV 16 and 18 infections, and associated abnormal cytology and precancerous stages of the disease (CIN). There is also evidence of cross protection against incident infection with HPV 31 and 45. The vaccine appears to be well tolerated, with a good safety profile.[vi],[vii]
GSKs HPV vaccine is formulated with the innovative adjuvant AS04. Studies have shown that the vaccine formulated with AS04 induced a stronger antibody response over a 48 month follow-up period, when compared to the same vaccine formulated with a conventional aluminium based adjuvant.
GSK applied to the European Agency for the Evaluation of Medicinal Products (EMEA) for an EU marketing authorisation for its HPV vaccine in May 2006, with submission to the US Food and Drug Administration expected by the end of 2006.
About HPV and cervical cancer
Cervical cancer is a major global health problem, with nearly 500,000 new cases occurring each year worldwide. It is the second most common cancer and the third leading cause of cancer deaths in women worldwide.[viii]
In the UK each year, almost 3,000 new cases of cervical cancer are reported[ix] and there are more than 1,000 deaths.8 It is the second most common cancer in women under the age of 35 years in the UK.9
Cervical cancer is not hereditary. It is caused by persistent infection with cancer-causing HPV. All women who have a sexual relationship are at risk of HPV.[x],[xi],[xii],[xiii]
HPV is very common and easily transmitted through close sexual contact[xiv] – full sexual intercourse is not necessarily required.[xv][xvi][xvii] The risk begins with first sexual activity.16,[xviii]
Up to 75% of sexually active women will be infected with HPV at some point in their lives.[xix],[xx]
There are cancer-causing and low risk strains of HPV. Cancer-causing strains can cause cervical cancer. The four most commons HPV strains associated with cervical cancer globally are 16 and 18, which account for approximately 70% of cervical cancers, and 31 and 45 which account for a further 10%.[xxi]
Cervical screening is an important preventative tool against cervical cancer and the UK operates a highly effective screening programme. It has been estimated that without a screening programme, up to 5,000 more UK women would die each year from cervical cancer.[xxii] Women should attend for regular cervical screening.
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