lymphoma staging, a system for classifying non-Hodgkin’s lymphomas according to the extent of the disease for the purpose of treatment and prognosis. The Ann Arbor staging system is commonly used to summarize the extent of the cancer in adults. The stages are described by Roman numerals I through IV, with stage IV indicating the highest level of involvement. Lymphomas that affect an organ outside the lymph system have E added to their stage, while those affecting the spleen have an S added. The letters A or B may also be added to a stage, B indicating the presence of symptoms associated with advanced disease. An X is added to the stage for tumors of the chest with characteristics that suggest the need for more intensive treatment.