Definition

A term used in the staging of neuroblastoma. It describes certain features of the tumor found on an imaging test, such as an MRI or CT scan, that affect how much of the tumor can be removed by surgery. For example, a tumor that surrounds major blood vessels, such as the aorta or vena cava, or involves two areas of the body, such as the neck and chest, is considered an IDRF. The presence of IDRFs means that it may be more difficult to remove the tumor safely and is a factor in how the stage of disease is determined. Also called image-defined risk factor.