New vaccines will protect against cancer

Mar 13 2006

The leading cancer charity in Britain is predicting that thousands of cancers will be prevented every year as specific vaccines are developed.

It is estimated that as many as one in three people will have some form of cancer in their lifetime; more than 275,000 new cancers are diagnosed in Britain each year and breast, lung, bowel and prostate cancers account for more than half of them.

The global number of virus-associated cancer accounts for more than 1.8 million cases of cancer each year, which equates to 18 per cent of all new cancer cases worldwide.

According to a new report by Cancer Research UK, vaccines against specific viruses could prevent one in ten cases of cancer in Britain.

The report also estimates that a handful of infections can trigger around one quarter of cancer cases in the developing world and suggests that vaccines could stop them.

The authors of the report stress that people cannot "catch" cancer, but some viruses can initiate the disease in some people.

Scientists know that almost all kinds of cancer develop through a series of genetic accidents, which when they accumulate cause a cell to become cancerous.

It seems for some cancers one of these genetic accidents is linked to infection.

Cancers linked to infection with particular viruses include cancers of the cervix, liver and nasal passages as well as certain types of lymphomas including some Hodgkin’s lymphomas and rare forms of leukaemia.

Many cases of stomach cancer are also linked to a common bacterial infection.

Although only a small proportion of virus-infected people develop these cancers, the global number of virus- associated cancer accounts for more than 1.8 million new cases of cancer each year, which is around 18 per cent of all new cancer cases worldwide.

Lead author of the report Professor Alan Rickinson, from the Cancer Research UK Institute at the University of Birmingham says that the study of the link 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.

This knowledge, he says helps us to trace other links in the chain and helps the understanding of how the whole chain fits together.

Rickinson says more importantly, if we can break the chain by preventing the infection through vaccination, then we can prevent the cancer developing.

Development of a vaccine for cervical cancer is well ahead; almost half a million cases of cervical cancer are diagnosed worldwide and almost are caused by the human papilloma virus (HPV); experts believe that the vaccine could prevent around 70 per cent of cervical cancer.

Dr Anne Szarewski, a clinical consultant at Cancer Research UK, says she believes the work being done on this vaccine is the most exciting development in cervical cancer research in many years.

She says they hope that by using HPV vaccines they will ultimately be able to prevent the majority of cases.

With any disease caused by a virus, says Szarewski, the best way to stop it is to prevent it with a vaccine but a number of questions remain unanswered, such as how long immunity will last, and if booster vaccines will be required.

To date 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.

There are 340,000 cases of primary liver cancer worldwide – half of which are linked to the Hepatitis B virus.

There are 2,784 cases of this cancer in the UK each year but a much lower percentage of these are linked to the virus.

No vaccines have yet been developed to help combat stomach cancer, nasopharyngeal carcinoma and the lymphomas and leukaemias associated with infections, but research continues into possible links between other cancers and underlying infection.

Professor John Toy, medical director of Cancer Research UK, says it is very important that people understand they cannot catch cancer in the way they can catch a cold or flu virus.

He believes soon it will be possible to vaccinate against certain types of cancer just as we successfully vaccinate against infectious diseases.