Ann Arbor Staging Classification

The Ann Arbor staging classification is a system doctors use to describe how far lymphoma (a type of blood cancer) has spread in the body. It uses Roman numerals I through IV: I indicates the cancer is in a single area or small region; II involves multiple areas on the same side of the diaphragm (a muscle that helps breathe); III means the disease is on both sides of the diaphragm; and IV indicates widespread involvement of organs outside the lymph nodes. Sometimes, additional letters are added to describe whether symptoms are present or the extra areas involved, helping guide treatment decisions.