Up to 30 newly-diagnosed female breast cancer patients will be recruited. Following written informed consent, participants will be invited for a baseline testing session. This will involve a fasting blood sample (ideally at a time when the patient's medical team would take a blood sample anyway). The investigators will analyse this sample for a number of markers of health, such as blood sugar and fat levels, and markers of inflammation. The investigators will measure the patients' height with a stadiometer, and weight and body fat percentage using a special set of scales. The investigators will ask patients to complete several questionnaires that ask questions about their current well-being. Finally the investigators will measure the patients' handgrip strength as well as their fitness levels. The grip strength test involves squeezing a handheld device as hard as possible for a few seconds. The fitness test involves cycling on a stationary bike with a gradually increasing resistance until the patient cannot continue any longer because of fatigue. In this test the investigators will ask patients to breathe through a tube to determine the maximal amount of oxygen they can take up during exercise. This measure (termed VO2max) is one of the best health markers that can be measured: it is the best predictor of future risk of chronic disease or premature death. All testing sessions will be performed at the Manor Hospital in Oxford (unless the equipment required for the analysis of VO2max is not available for a period of time, in which case patients will be invited to attend Oxford Brookes campus for the fitness test; this is a 4-minute drive from the Manor Hospital).