By Michelle Roberts
Health editor, BBCNews online
One in six cancers - two million a year globally - are
caused by largely treatable or preventable infections, new estimates suggest.
The Lancet
Oncology review, which looked at incidence rates for 27 cancers in
184 countries, found four main infections are responsible.
These four - human papillomaviruses, Helicobacter pylori and
hepatitis B and C viruses - account for 1.9m cases of cervical, gut and liver cancers.
Most cases are in the developing world.
The team from the International Agency for Research on
Cancer in France, part of the World Health Organization, says more efforts are
needed to tackle these avoidable cases and recognise cancer as a communicable
disease.
'Preventable'
The proportion of cancers related to infection is about
three times higher in parts of the developing world, such as east Asia, than in
developed countries like the UK - 22.9% versus 7.4%, respectively.
“Start Quote
Infection prevention ...could have a substantial effect
on the future burden of cancer worldwide”
Dr Catherine de Martel and Dr Martyn Plummer
Nearly a third of cases occur in people younger than 50
years.
Among women, cancer of the cervix accounted for about half
of the infection-related cancers. In men, more than 80% were liver and gastric
cancers.
Drs Catherine de Martel and Martyn Plummer, who led the
research, said: "Infections with certain viruses, bacteria, and parasites
are some of the biggest and preventable causes of cancer worldwide
"Application of existing public-health methods for
infection prevention, such as vaccination, safer injection practice, or
antimicrobial treatments, could have a substantial effect on the future burden
of cancer worldwide."
Vaccines are available to protect against human
papillomavirus (HPV) - which is linked to cancer of the cervix - and hepatitis
B virus - an established cause of liver cancer.
And experts know that stomach cancer can be avoided by
clearing the bacterial infection H. pylori from the gut using a course of
antibiotics.
Commenting on the work, Dr Goodarz Danaei from Harvard
School of Public Medicine in Boston, the US, said: "Since effective and
relatively low-cost vaccines for HPV and HBV are available, increasing coverage
should be a priority for health systems in high-burden countries."
Jessica Harris of Cancer Research UK said: "It's
important that authorities worldwide make every effort to reduce the number of
infection-related cancers, especially when many of these infections can be
prevented. In the UK, infections are thought to be responsible for 3% of
cancers, or around 9,700 cases each year.
"Vaccination against HPV, which causes cervical cancer,
should go a long way towards reducing rates of this disease in the UK. But it's
important that uptake of the vaccination remains high. At a global level, if
the vaccine were available in more countries, many thousands more cases could
be prevented."
