Population aging is associated with greater numbers of older people with cancer. Thanks to treatment advances, not only are more seniors diagnosed with cancer, but there are also more and more older cancer survivors. This upward trend will continue. Given the heterogeneity of aging, managing older patients with cancer poses a significant challenge for Medical Oncology. In Spain, a Geriatric Oncology Task Force has been set up within the framework of the Spanish Society for Medical Oncology (SEOM). With the aim of generating evidence and raising awareness, as well as helping medical oncologists in their training with respect to seniors with cancer, we have put together a series of basic management recommendations for this population. Many of the patients who are assessed in routine clinical practice in Oncology are older. CGA is the basic tool by means of which to evaluate older people with cancer and to understand their needs. Training and the correct use of recommendations regarding treatment for comorbidities and geriatric syndromes, support care, and drug-drug interactions and toxicities, including those of antineoplastic agents, as detailed in this article, will ensure that this population is properly managed.