Measuring Fluid Buildup in Cancer Patients

The goal of this study is to improve the monitoring of fluid retention in cancer patients. The main question it aims to answer is: Can segmental bioelectrical impedance analysis be used to monitor local fluid retention (edema) in cancer patients? We will include: * Breast cancer patients with fluid and or lymph retention in one or both arms after radiotherapy (outpatients) * Cancer patients with fluid retention in one or both legs after chemotherapy (hospitalized) Participants will: * Have measurements taken using bioelectrical impedance * Provide blood samples and 24-hour urine collection * Weight monitorering * Complete diet and fluid registration (inclusive enteral and parenteral) * Have clinical palpatory and measurement assessment of oedema.