Continuous versus split-course irradiation for lung cancer. Immunological implications

The therapeutical irradiation for lung cancer causes profound disturbances of host's general immunocompetence, the cellular immunodepression being the dominant finding. It is thought that split-course technique holds certain advantage over the continuous irradiation, since the former includes an interruption of 4 week duration, thus allowing the lymphopoietic system to recover to a certain degree. In this report, we compared the radiotherapy-due alterations of several parameters of cellular immunity (the number and function of total T cells, active T cells and the cells of monocyte/macrophage lineage), immediately after the completion of therapy in either continuously (n = 13) or split-course-irradiated (n = 12) lung cancer patients. All patients had received the total dose of 60 Gy. Both therapeutical techniques caused alterations of the parameters tested: the significant decrease of the total and active T cells and their proliferative responses, while the phagocytic activity and the number of mononuclear phagocytes were increased, the latter being affected to a lesser extent in split-course-treated patients. Our results suggest that both techniques have similar immunodepressant effect on the cellular immunity of lung cancer patients.