. . . "This helps them to know when treatment is needed and which treatment is appropriate for each person.The stage of non-Hodgkin lymphoma describes how many groups of lymph nodes are affected, where they are in the body and whether other organs such as the bone marrow or liver are involved.Stage 1One group of lymph nodes is affected - for example in the armpit, on one side of the neck or in the groin." . . . .