Abstract
Lost and remaining functions are of special importance in geriatric medicine. The level of functional deficits ultimately determines the remaining quality of life and the patient's ability to continue independently. In contrast, the actual severity of a disease measured by common standards becomes less important. Geriatric assessment is increasingly used to describe the impact of disease and to focus on the functional losses and problems that are particularly relevant to the individual elderly patient. When developing a treatment plan for older cancer patients, it is essential to consider the functional deficits caused by age-related changes or comorbidity, the remaining compensation mechanisms and the patient's expectations. Cancer treatment has to be adapted to the individual needs of elderly patients. As the number of cancer patients is rising in all areas of medical practice, a close collaboration between oncologists and geriatricians will become increasingly important.