Unfortunately there is much less evidence about the effect of diet on the progression of cancer than about its effect on the likelihood of developing cancer in the first place. And it may depend on what type of cancer you have.

For people diagnosed with breast cancer, there is substantial evidence that being a healthy weight and being physically active can each improve quality of life, and are linked to increased survival.

There is not enough evidence to make firm recommendations for other cancers, nor to say that a particular type of food or diet helps, but most authorities recommend following the general recommendations for cancer prevention in people who have already been diagnosed with cancer (unless there is a medical or other reason why they should not). And remember, don’t take any supplements without first checking with your doctor – some have been shown to interfere with cancer treatments.