A vaccine that can train cancer patients' bodies to seek out and destroy tumour cells has been developed by scientists.

The therapy, which targets a molecule found in 90% of cancers, could provide a universal injection that would allow patients' immune systems to fight off common cancers including breast and prostate cancer.

Preliminary results from clinical trials have suggested that the vaccine can trigger an immune response in patients and reduce levels of disease.

The scientists behind the vaccine hope to conduct more extensive trials in patients to prove it can be effective against a range of cancers.

They believe it could be used to fight small tumours if they are detected early enough or to help prevent the return and spread of disease in patients who have undergone other forms of treatment such as surgery.

Cancer cells usually evade a patient's immune system because they are not recognised as a threat. While the immune system usually attacks foreign cells such as bacteria, tumours are formed of the patient's own cells that have malfunctioned.

However, scientists have discovered that a molecule called MUC1, which is found on the surface of cancer cells, can be used to help the immune system detect tumours.

The new vaccine, ImMucin, has been developed by the drug company Vaxil Biotherapeutics and researchers at Tel Aviv University. It uses a section of the molecule to prime the immune system so it can identify and destroy cancer cells.

Vaxil Biotherapeutics said: "ImMucin generated a robust and specific immune response in all patients which was observed after only two to four doses of the vaccine out of a maximum of 12 doses. In some of the patients, preliminary signs of clinical efficacy were observed."

The results are still to be published formally, but if further trials prove to be successful the vaccine could be available within six years.

As a therapeutic vaccine it is designed to be given to patients to help their bodies fight cancer rather than to prevent disease in the first place.

Cancer cells contain high levels of MUC1, as it is thought to be involved in helping tumours grow. Healthy cells also contain MUC1, but in levels that are too low to trigger the immune system after vaccination.

When a vaccinated patient's immune system encounters cancer cells, however, the larger concentration of MUC1 causes it to attack and kill the tumour. As MUC1 is found in 90% of cancers, the researchers believe it could be used to help fight the growth and spread of a wide range of cancers.

In a safety trial at the Hadassah Medical Centre in Jerusalem, 10 patients suffering from multiple myeloma, a form of blood cancer, have received the vaccine.

Seven have finished the treatment and Vaxil reported that all had greater immunity against cancer cells compared with before they were given the vaccine. Vaxil added that three patients were free of detectable cancer following the treatment.

The findings support research published in the journal Vaccine, which suggested that the treatment induced "potent" immunity in mice and increased their survival from cancer.

Cancer charities have given the vaccine a cautious welcome. Dr Kat Arney, the science information manager at Cancer Research UK, said: "These are very early results that are yet to be fully published, so there's a lot more work to be done to prove that this particular vaccine is safe and effective in cancer patients."