Increasing life expectancy results in an increased number of elderly cancer patients. Comorbidities and functional impairment influence the patient's course of disease and the choice of antineoplastic treatment. The Comprehensive Geriatric Assessment (CGA) supports the appraisal of the patient's individual health characteristics, especially due to the fact that chronologic age does not always correlate with the patient's health. Next to the appraisal of comorbidities and functional impairment, nutritional state, cognitive impairment, psychological state, social support, quality of life and the patient's medication are recorded. The Society of Geriatric Oncology (SIOG) recommends the CGA in cancer patients older than seventy years. While planning a systemic antineoplastic therapy, renal, hepatic, cardiac and bone marrow insufficiencies have to be considered. Renal and hepatic impairment often cause in dose reduced antineoplastic treatment, whereas in patients with cardiac insufficiency liposomale substances and in patients with decreased bone marrow function growth factors are available. Additionally to the oncological treatment, an early involvement of palliative care specialists should be considered.