This chapter discusses: current evidence in the field of aging and cancer; the integration of geriatric principles in oncology; the content of a Comprehensive Geriatric Assessment; Comprehensive Geriatric Assessment in routine practice; international perspective. Due to growth of the aging population and a prolonged exposure to carcinogens, cancer has become an important disease in older people. Cancer is a very serious health problem at any age; however, combined with increasing age, it creates even more challenging situations for healthcare providers. Medical and radiation oncologists are faced with another challenge since evidence-based data of the risks and benefits of cancer treatments in older patients are lacking. Up to 40 per cent of general geriatric patients are found to be at risk for malnutrition, and without proper nutritional support, an intensive cancer treatment could induce cachexia. The incidence of cancer, particularly gynaecologic malignancy, increases with advanced age.