The discovery could lead to the vaccine being approved for experimental use within a year, according to one specialist.

The vaccine was most effective when given to patients in the early stages of the disease.

The vaccine was made from a mixture of the patients' cancer cells and bacteria. It was effective for subjects whose cancer had broken through the bowel wall but had not spread further.

The findings were published in The Lancet medical journal on Friday.

Widespread killer

Cancer of the colon is a common form of cancer but is treatable if diagnosed at an early stage.

Even so, it is the second most common cancer in the UK after lung cancer and kills nearly 20,000 people a year.

The usual treatment starts with surgery, and can go on to include radiation therapy and chemotherapy, especially if the cancer has progressed far.

Following surgery, there is always the danger that small pieces of cancer remain, which can cause a recurrence of the disease.

The research suggests that a vaccine could help destroy any remaining cancerous growths.

It was carried out by researchers from Vrije University Hospital in Amsterdam, in the Netherlands.

Early intervention

The project studied 254 patients. Of these, 170 patients had early, or stage II colon cancer, where the tumour has eroded through the bowel wall but has spread no further.

Radiation therapy can be used to kill cancer cells

The other 84 had stage III cancer, where the cancer has travelled to the lymph nodes.

Half of each group was randomly chosen to have the vaccinations, while the other half got placebo injections.

The injections began a month after surgery, and were given three times a week. They contained neutralised cancer cells mixed with bacteria that boost the immune system.

Patients were given a booster shot of the cancer cells alone six months later. They were then monitored for five years.

The patients with stage II cancer had a 61% reduced risk of recurrence with the vaccine. Cancer recurred in 10 of the 85 who had been vaccinated and in 23 of the 85 who had not been vaccinated, the researchers said.

However, the injections seemed to have little effect in cases where the cancer had spread to the lymph nodes.

Side-effects of the vaccine included fever and flu-like symptoms during the first few days and leg ulcers that remained for about two months.

Public awareness

The World Health Organisation says about 780,000 people worldwide are diagnosed with colon cancer every year.

Many people ignore the warning signs, and public health campaigns have tried to draw familiarise the public with the symptoms of the cancer.

These include:

• Fresh blood in the stools

• Lasting change in normal bowel habits, diarrhoea or constipation for example

• Weight loss

• Pain in the abdomen or rectum

• Strained feeling in the rectum

The cancer also commonly causes anaemia.

This can cause a blockage, which is called a bowel obstruction. The symptoms of this are:

• Being sick

• Constipation

• Feeling bloated

• Griping pains in the abdomen

About 80% of patients who have the cancer diagnosed in the early stages can expect to live five years.

The researchers hope the vaccine could raise this rate to 90%.

'Substantial advance'

Dr Gabriel Feldman, director of colon cancer of the American Cancer Society, said the trial could lead to the vaccine being approved for experimental use in cancer treatment within a year.

He said: "We have nothing beyond finding the disease early that impacts the disease greatly.

"This is a substantial advance because it's going to change the management of patients with (early stages) of the disease."

In the past, vaccines have been used to prevent people from catching diseases by arming the immune system to fight off invaders.

In the new approach, doctors give a vaccine to people who are already sick in an effort to trigger the immune system to find and destroy cancer cells.