The role of splenic irradiation in chronic lymphocytic leukemia

Fourteen patients with chronic lymphocytic leukemia (CCL) who received a total of 23 courses of splenic irradiation (SI)for various combinations of painful splenomegaly, progressive leukocytosis, lymphocytosis, thrombocytopenia, and anemia are reviewed. Splenic midplane doses ranged from 200-1750 rads (3-14 days), while the most typicalregimen was 300-450 rads in two to three fractions of 150 rads given over 3-8 days. Response to SI was rated according to a scoring system which evaluated the splenic and hematologic response, as well as the response of disease-related symptons. According to this scoring system, most patients demonstrated a significant relief of painful splenomegaly, along with improvement of hemogram and bone marrow parameters. While those patients judged as failures to prior chemotherapy or total body irradiation showed improvement following SI, those who had received minimal therapy prior to SI showed a superior response. SI, in those showing a satisfactory response, was repeated successfully in several patients (up to six times in one instance). The onset and duration of response to SI, dose-reponse data, survival, clinical and hemotologic responses, and the possible mechanism of action of SI are discussed with reference to the available literature.