Cancer is a disease of older people, but this age group has often been excluded from clinical trials of cancer, which leads to poor transportability of standardized treatments in older cancer patients. One of the main reasons for the exclusion is the heterogeneity of older people in several domains: social environment, comorbidities, dependency, functional status, nutritional status, cognition status, and mood status. Comprehensive geriatric assessment aims to assess this heterogeneity and has identified frequent health problems often unknown before therapeutic decisions, which allows for targeted geriatric interventions with or without follow-up and appropriate cancer treatment selection. Several tools and scores have been developed for a complementary approach. These tools have the following characteristics: they screen for vulnerability to select patients who may benefit from a comprehensive geriatric assessment; are predictive tools for survival, postoperative complications, or chemotherapy-related toxicity; are decisional algorithms for cancer treatment; or define a core set of geriatric data to be collected in clinical cancer trials. Here, we present an overview of the geriatric tools that were published in PubMed from 2000 to 2017, that could help in the therapeutic decision-making for older cancer patients.