Cancer in the older person is an increasingly common problem, due to the progressive prolongation of the life-expectancy of the Western population. This article reviews the mechanisms associating aging and cancer, age-related changes in cancer biology, assessment of the older person to estimate life-expectancy, treatment tolerance, and medical and social conditions that may interfere with cancer treatment, effectiveness of cancer prevention and cancer treatment in older individuals. A comprehensive geriatric assessment (CGA) is commonly used to predict life-expectancy and functional reserve and to unearth conditions that may jeopardize cancer prevention and treatment. In the interest of cost and time, shortened forms of CGA are being explored. Chemoprevention of cancer is a promising form of prevention that at present has no conclusive clinical indications. Early diagnosis of breast and colon cancer through screening of asymptomatic patients at risk may be beneficial for individuals with a life-expectancy of 5 years or longer. Early detection of lung cancer in ex-smokers is undergoing clinical trials, as this disease is becoming more and more common. Age should not prevent appropriate treatment of cancer in older individuals, especially in those with adequate life-expectancy and functional reserve. The National Cancer Center Network (NCCN) has issued a series of guidelines to minimize the toxicity and promote the effectiveness of cancer in older patients. Important interventions include prevention of neutropaenic infections with filgrastim and peg-filgrastim, prevention of anaemia with epoietin or darbepoietin, and prevention and early management of mucositis.