A radiotherapeutic experience for localized extranodal non-Hodgkin's lymphoma: prognostic factors and re-evaluation of treatment modality.
Between 1966 and 1988, 149 patients were treated with radiotherapy for localized extranodal lymphoma. The average total dose given was 39.8 Gy for low grade disease and 48.7 Gy for all other disease. Of the 149 patients, 60 also received adjuvant chemotherapy. Twenty-four had low grade lymphoma, 109 had intermediate grade disease, and 16 had high grade disease, histologically. The distribution of histological grade and T/B phenotype varied with the primary site. Low grade lymphomas were found mainly in the orbit, and T-cell lymphomas were found in the nasal cavity and nasopharynx. The 5-year survival rates according to tumor location were 89% for oral cavity, 86% for paranasal sinus, 83% for thyroid, 69% for orbit, 47% for Waldeyer's ring (WAR), 44% for testis, 23% for CNS, 21% for nasal cavity and 60% for other sites. Histological grade and T/B phenotype both had prognostic importance. Combined chemotherapy significantly improved the survival rate only for disease with intermediate or high grade histology. Other prognostic factors according to the primary site were the bulk of lymph node for WAR disease, the radiation dose for CNS disease, bone erosion for orbital disease, stridor for disease of the thyroid, and the tumor stage for disease of both the testis and the thyroid.