A study found that almost four in ten patients with aggressive prostate cancer did not need planned surgery or radiotherapy after making simple lifestyle changes.

Doctors found that the adjustments slowed down or even halted the progression of their disease.

And they claim that there is no reason that the benefits could not be seen in other types of cancer.

Previous studies have shown that adopting a more healthy lifestyle can help to prevent different types of cancer developing.

Rising obesity rates have been linked to at least six different types of cancer, including breast cancer, the most common form of the disease in women.

Researchers at Addenbrooke's hospital in Cambridgeshire decided to test the effects of adopting a healthy lifestyle in 110 men who had been diagnosed with the aggressive form of prostate cancer.

Changes made included cutting down on salt and alcohol, eating more oily fish, losing weight and taking moderate amounts of regular exercise.

Some of the patients were also given vitamin and mineral supplements, which the findings show made no difference to their cancer.

All the patients also took small doses of aspirin, although the researchers say that there was no conclusive evidence that the drug helped patients.

Doctors monitor the progression of prostate cancer using a test for Prostate Specific Antigens (PSA).

These rise as tumours grow, but doctors found that lifestyle changes caused levels to stabilise and even fall for some patients in the trial.

The findings show that 40 of the patients, 36 per cent, did not need further treatment.

Robert Thomas, a consultant oncologist, from Addenbrooke's, who led the study, said: "Because prostate cancer is very slow growing it is possible for us to monitor its progress.

"(The same thing) is hard to evaluate other cancers. It would not be correct to delay chemotherapy or surgery to see whether the effects of a healthy lifestyle would be the same in breast cancer, for example.

"The main benefit of lifestyle changes in other types of cancer would probably be in helping to ensure that the disease did not recur."

Paul Sinclair, from Bedford, who took part in the trial, started drinking more pomegranate juice as one of the adjustments to his lifestyle.

He said that he was surprised in the difference that the changes made to his condition.

He said: "We followed (the disease) with a series of blood tests to monitor the levels, and they started reducing.

"The results I had in April/March this year were nearly normal, really much to my surprise."

Prostate cancer affects more men in Britain than any other form of the disease.

About 35,000 men are diagnosed with the condition every year and a third go on to die from the disease.