MEN with prostate cancer are much more likely to die from the disease if they fail to eat healthily after being diagnosed, a study has found.

Those most wedded to a "Western" diet containing a lot of red and processed meat, fat and refined grains, were two-and-a-half-times more likely to die from a prostate cancer-related cause than men least likely to eat such foods.

Western diet consumers also had a 67 per cent increased risk of dying from any cause, while overall death rates of men choosing a "prudent" diet rich in vegetables, fruit, fish and beans were reduced by 36 per cent.

Researchers analysed health and diet data on 926 men participating in a US investigation called the Physicians' Health Study who were diagnosed with prostate cancer.

After diagnosis, the men were followed for an average of 14 years and placed in one of four groups according to the extent to which they embraced a typical Western diet.

Researcher Dr Jorge Chavarro, from the Harvard TH Chan School of Public Health in Boston, US, said: "There is currently very little evidence to counsel men living with prostate cancer on how they can modify their lifestyle to improve survival.

"Our results suggest that a heart-healthy diet may benefit these men by specifically reducing their chances of dying of prostate cancer."

Prostate cancer is the most common form of the disease among men in Scotland, with more than 3,100 new cases diagnosed each year. There were 876 deaths from the disease in 2013, according to the latest official figures.

The findings appear in the journal Cancer Prevention Research.

Lead author nutritional scientist Dr Meng Yang, also from the Harvard TH Chan School, pointed out that all the study participants were physicians and white.

"It is very important that our results are replicated in other studies with more diverse socioeconomic and racial/ethnic backgrounds," she said.

Previous studies have suggested that some foods may slow down the growth of prostate cancer or reduce the risk of it returning after treatment, but the evidence is limited.

Examples include soya products, pulses such as kidney beans, chickpeas and lentils, broccoli, kale and other cruciferous vegetables, cooked and processed tomatoes, green tea and pomegranate juice.

Good food sources of the mineral selenium, but not supplements, are also said to be beneficial. They include Brazil nuts, liver, kidney, fish, seafood and poultry.

*Meanwhile, a drug that frees the immune system to attack a devastating form of lung cancer has been shown to double the life expectancy of genetically targeted patients.

Nivolumab is one of new generation of immunotherapy drugs that release cancer-applied brakes on the immune system called "checkpoints".

The results, from a major international trial involving patients who had already been treated for the most common form of lung cancer, were described by one expert as a "paradigm shift".

In the Phase III trial, the last step before a drug is licensed for use in clinics, researchers compared the effectiveness of nivolumab and the standard chemotherapy drug docetaxel in 582 patients with advanced non-squamous non-small cell lung cancer (NSCLC).

The disease accounts for around 85 per cent of all cases of lung cancer, which is diagnosed in 43,463 new patients and causes 35,371 deaths each year in the UK.

Overall, nivolumab reduced the risk of dying by 27 per cent compared with docetaxel and increased typical survival time from 9.4 to 12.2 months.

But the drug was found to be most effective in patients whose cancers produced higher levels of a tumour protein called PD-L1, potentially paving the way to personalised treatments.

Dr Alan Worsley, senior science information officer at Cancer Research UK, said: "Advances like these are giving real hope for lung cancer patients, who have until now had very few options."