Vaccines 'may block many cancers'

Anti-viral vaccines have the potential to prevent one in ten cases of cancer in Britain, and as many as 25% in the developing world, a report says.

The Cancer Research UK study estimates there are more than 1.8 million new cases of virus-associated cancer world-wide each year.

The charity says just a handful of viruses are to blame.

It says greater investment in new vaccines could be a highly productive way to combat cancer.

Cancers linked to infection with particular viruses include:

• Cervix

• Stomach

• Liver

• Nasopharyngeal carcinoma (nasal passages)

• Lymphomas

• Leukaemia

The report stresses that only a small proportion of people infected with viruses linked to cancer go on to develop the disease.

However, it estimates that as many as 18% of new cases of cancer each year are linked to viral infections.

Lead researcher Professor Alan Rickinson, from the University of Birmingham, said: "Studying the association between infectious agents and human cancers is extremely important because, in such cases, infection represents one defined link in the chain of events leading to cancer development.

"Knowing this helps us to trace other links in the chain and to understand how the whole chain fits together.

"More importantly, if we can break the chain by preventing the infection through vaccination, then we can prevent the cancer developing."

Vaccine development is most well advanced in the case of cervical cancer, which is largely caused by infection with the human papilloma virus (HPV).

Rival products

Rival drug companies are battling to bring products to market, with the expectation that they could prevent around 70% of all cases of the disease.

However, Dr Anne Szarewski, clinical consultant at Cancer Research UK, said there was still work to be done.

"We don't know yet how long immunity will last, and if booster vaccines will be required.

"The longest period for which women have been followed up after an HPV vaccine trial has been four years."

A vaccine has also been developed for the Hepatitis B virus which is linked to liver cancer.

No vaccines have yet been developed to help combat stomach cancer, nasopharyngeal carcinoma and the lymphomas and leukaemias associated with infections.

Professor John Toy, medical director of Cancer Research UK, said it was important people understood it was not possible to "catch" cancer, in the same way as a cold or flu virus.

But he added: "As today we successfully vaccinate against infectious diseases so we shall soon be able to vaccinate against certain types of cancer."