RECIST 1.1 criteria are the standard for the response assessment of most solid tumors on computed tomography (CT). Nevertheless, the emergence of new classes of treatment in the lasts decades has brought new challenges in the evaluation of response. A PubMed online database literature search was performed in order to identify papers in English with full text available published up to September 2017. Some oncologic treatments, such as antiangiogenic agents, immunotherapy and local treatments, have proven to be effective despite atypical patterns of response. In patients undergoing these treatments, size-based evaluations, such as RECIST1.1, show some limitations, since they often underestimate the response. Some modified criteria have been proposed to improve the response assessment in several specific settings, such in gastrointestinal stromal tumors treated by antiangiogenic agents, hepatocellular carcinoma treated by local ablation or solid tumors treated by immunotherapy. New techniques of image analysis and imaging modalities other than CT, such as magnetic resonance imaging and positron emission tomography, may provide additional information and amend some of the limitations of size-based criteria. The emergence of new treatment paradigms and the increasing trend toward personalizing treatment should be associated with a concomitant evolution of response assessment, in both research and clinical settings.