Cancer in the older person has become an increasingly common problem with the aging of the population. The goal of this paper is to review the influence of age on cancer biology and cancer management. Specific interactions of cancer and aging include: Increased incidence of cancer with the age: This association may be reported to three factors: duration of carcinogenesis; increased susceptibility of older tissues to late stage carcinogens, and systemic effects of aging, including immune-senescence and enhanced cytokine production. Biological behavior of cancer: With aging, the prognosis of certain neoplasms, including acute myelogenous leukemia and large-cell non-Hodgkin's lymphoma worsens, whereas the behavior of other tumors becomes more indolent. In these biologic variations one may recognize both a 'seed" effect (different tumor cells) and a "soil" effect (different ways in which the older tumor host handles tumor growth. Goals of prevention and treatment: Given the limited life-expectancy of older individuals and reduced tolerance of clinical intervention, the main goal is compression of morbidity, rather than prolongation of survival. Cancer prevention in the older person: In virtue of increased susceptibility to environmental carcinogens, the older person appears an ideal candidate for primary prevention of cancer, including chemoprevention; though randomized controlled studies have not been performed, the older person may benefit from secondary prevention (screening), when the average life-expectancy is 3 years or longer. Cancer treatment: The risk of surgical complications increases only slightly with age for elective surgery, but increases dramatically for emergency surgery. Radiation therapy appears a valuable method of cancer treatment in patients of all ages. Chemotherapy can be made safer by the following provisions: use of hemopoietic growth factors for patients aged 70 and older receiving moderately toxic chemotherapy (CHOP and CHOP-like); maintenance of hemoglobin levels at 12 g/dl with erythropoietin; adjustment of the dose of renally excreted agents to the glomerular filtration rate; selection of the best candidates for chemotherapy based on comprehensive geriatric assessment.