Source:http://linkedlifedata.com/resource/umls/id/C1518527
NCI: A type of study in which individuals are observed or certain outcomes are measured. No attempt is made to affect the outcome (for example, no treatment is given).,NCI: Studies in which biomedical and/or health outcomes are assessed in pre-defined groups of individuals. Subjects in the study may receive diagnostic, therapeutic, or other interventions, but the investigator does not assign specific interventions to the subjects of the study.,NCI: Studies among cancer patients and healthy populations that involve no intervention or alteration in the status of the participants.