For the second hypothesis, the objective will be to determine to what extent the number of CTCs and the degree of platelet cloaking varies in exposed and non-exposed groups following a supervised exercise intervention, and to compare this with a non-exercised comparison group. The exercise intervention will prescribe moderate intensity aerobic exercise that will be supervised once per week for 3 months and completed independently at home for a further 3 months. Patients will wear Polar heart rate monitors to monitor exercise prescription and progression. Assessments including blood sampling and quality of life questionnaires will be completed at baseline, 3 months and 6 months.