A dream that has inspired cancer researchers for more than a quarter of a century has come true. The first vaccine to prevent cancer has won a licence and will be in use by the end of the year.

The approval by the US Food and Drug Administration (FDA) of Gardasil, a vaccine to prevent cervical cancer, has reawakened interest in the whole field of cancer vaccines. Gardasil, from Merck, and its rival Cervarix, from GlaxoSmithKline (GSK), will prevent infection by human papilloma virus, which causes cervical cancer. They will save thousands of lives every year.

True, cervical cancer is a special case, as it is known to be caused by a virus. Most cancers are not, so simple vaccines to prevent and treat them are less readily devised. But after years of disappointment, hopes are rising that vaccines against a wide range of cancers may prove effective. Is the tide turning? Some eminent people people think so.

Last week GSK announced results from a trial of its lung cancer vaccine, which produced a one-third reduction in the chances of cancer recurring after surgery, compared with a placebo. Lung cancer is one of the toughest cancers to treat, so these results — though not statistically significant — were “very encouraging”, GSK said. Bigger trials will follow.

Other straws in the wind include good results in tackling prostate and skin cancers, and non-Hodgkin’s lymphoma. If the scale of effort is any guide, cancer researchers and drug companies believe that vaccines can at last make a real contribution. There are more than 100 cancer vaccines in late-stage development from more than 75 companies, and although many will fail, in the next five years about 50 should be launched, analysts believe.

Cancer specialists foresee the day when cancer will be “just another disease”, not the death sentence that it used to be. There will be cures, but most patients are unlikely to be cured completely. For them, it will become a disease that they live with rather than die from.

Already the number of people in this group is growing fast, partly as a result of earlier diagnosis, partly longer survival. But by 2025 this group will be many times larger as cancer vaccines make it possible to blunt the disease’s cutting edge.

Unlike Gardasil and Cervarix, most cancer vaccines are designed not to prevent cancer but to treat it. The reason cancer can spread is that the immune system is often poor at recognising cancer cells as “foreign” and attacking them. Essentially, tumour cells appear normal to it — and even when an attack is launched, cancer cells can develop ways of “hiding”, perhaps by reducing the number of proteins on the cell surface that are normally the targets of antibodies.

The aim of cancer vaccines is to restore or strengthen the immune system’s ability to attack cancer cells. The idea is far from new but for many years made little progress.

“Twenty years ago, people didn’t realise how little they knew about the immunology of cancer,” says Dr Jose Lutzky, of Mount Sinai Medical Centre in Miami Beach. Typically, early results were encouraging but the vaccines failed as soon as large trials were attempted. “The whole field was riddled with high expectations,” says one US researcher. “Then everybody failed.”

Despite this, the idea remains so attractive that research has continued and is growing.Several different methods are being used. The simplest idea is to combine fragments of a cancer cell with an adjuvant — a material known to provoke the immune system into action — in hope that this will create a much stronger immune response.

Another approach is to take specialised white blood cells from the patient, mix them with the cancer cells, then inject them back. Similarly, the idea is that these dendritic cells — the most powerful immune-inducing cells in the body — will help the immune system to recognise and attack the cancer.

Last year the first concrete success for a vaccine using dendritic cells was published. Provenge, made by a Seattle-based company, used dendritic cells taken from prostate cancer patients and engineered them to produce a protein found in about 95 per cent of prostate cancer cells.