Staging refers to the use of several diagnostic tests to determine to what extent, if any, the cancer has spread in the body. Staging may include blood work sampling regional and distant lymph nodes, thoracic (chest) radiographs, abdominal radiographs or ultrasound, CT scan, MRI scan, , special stains, or bone marrow aspiration. Staging is important in determining the prognosis of a cancer and what treatment options are recommended.