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NCI Dictionary of Cancer Terms


EFS   

  In cancer, the length of time after primary treatment for a cancer ends that the patient remains free of certain complications or events that the treatment was intended to prevent or delay. These events may include the return of the cancer or the onset of certain symptoms, such as bone pain from cancer that has spread to the bone. In a clinical trial, measuring the EFS is one way to see how well a new treatment works. Also called event-free survival.