Cancer in the older person is increasingly common. The biological interactions of cancer with age are only partly understood and may provide some clues to future forms of cancer prevention and treatment. Management-related decisions in a population with limited life expectancy and limited functional reserve should be based on the natural history of the cancer, the patient’s life expectancy, and the patient’s tolerance of treatment. In addition, financial and caregiver considerations are important in assessing the treatment’s benefits and risks. Cooperation between geriatricians and oncologists seems to be essential to generate predictive models, as well as outcome information to improve the decision making in older cancer patients. It may also be essential in caring for a host of older cancer survivors. In France, this cooperation is already a reality that finds its expression in a network of units of oncogeriatrics distributed throughout the country.