RATIONAL: Patients diagnosed with malignant hematological diseases undergoing HSCT are faced with poor prognosis. The treatment is demanding and associated with severe deconditioning potentially leading to worse prognostic outcomes. To what extend patients body composition at the point of referral to HSCT, as well as changes in body composition throughout the cancer continuum is associated with cancer outcomes is currently not well described, specifically if this should be part of standard clinical evaluation in order to optimize therapy-efficacy. Recent findings suggest that pathophysiological alterations in skeletal muscle mass and function can have significant implications for the risk of disease progression and long term prognosis.