<qa>  What is an omega-3-fatty acid?Eicosapentaenoic acid EPA is an omega-3-fatty acid, derived from fish oil and a commonly available nutritional supplement. It is believed to reduce the inflammatory effect of cancer and the trauma of surgery, in turn dampening the catabolic effect causing skeletal muscle loss. Studies on oesophageal cancer patients have previously suggested that EPA can preserve lean muscle mass 5. The investigators expect EPA to cause less lean muscle loss and improved aerobic performance. High dietary intake is not thought to have health risks 6 and EPA has recently been trialed in infant milk formulas with no adverse effects 7. 