The concept and evolution of involved site radiation therapy for lymphoma
In contrast to Hodgkin's lymphomata, non-Hodgkin's lymphomata originate in approximately a fourth of the cases in extranodal organs and sites. The prognosis of patients with primary extranodal organ involvement of the non-Hodgkin's lymphomata is similar to that of patients with primary lumph node involvement of the Hodgkin's and non-Hodgkin's lymphomata, dependent on the special spreading of the disease corresponding to the 4 stages of the Ann Arbor classification. This applies to the primary involvement of a single lymph node region (Stage I) or a single extralymphatic organ or site (stage IE) as well as to further stages of spreading within the lymphatic system (Stages II and III) including secondary localized involvement of an extralymphatic organ and site (Stages IIE and IIIE). The same qualitative dependence of the prognosis of Hodgkin's and non-Hodgkin's lymphomata on the spatial spreading, corresponding to the Ann Arbor concept, legitimizes, in spite of some quantitative differences, the application of the Ann Arbor classification system to all malignant lymphomata.