RESUMEN
PURPOSE: This study was undertaken to retrospectively evaluate white blood cell kinetics, especially lymphocyte depression after different treatments, and to find the correlation between immunosuppression and large blood volume and dynamic blood flow within the mediastinal radiotherapy (RT) field in lung cancer. MATERIALS AND METHODS: Thirty-four patients with lung cancer were retrospectively evaluated; 10 patients had only radiotherapy (RT group), 8 had chemotherapy (CT group) and 16 had chemotherapy and radiotherapy (RT/CT group). The mean follow-up periods of the RT-including groups (RT group and RT/CT group) and the RT-excluding group (CT group) were 6 and 8 months, respectively. Complete blood cell counts including lymphocyte percentage (%) were checked weekly during RT but less frequently during CT and after RT. RESULTS: Changes in total white blood cell counts were not significantly different among the three groups. The lymphocyte count and lymphocyte % were much lower in the RT-including groups than in the RT- excluding group. The difference between pre-treatment and final lymphocyte count and the difference between pre-treatment and final lymphocyte % were significant (p=0.044 and p=0.037) between the RT- including groups and the RT-excluding group. CONCLUSION: Lymphopenia was more marked after treatment containing RT than CT only. Lymphopenia may be one cause of a compromised immune system after mediastinal irradiation in lung cancer. We suggest cautiously that previous studies showing evidence of lymphocyte apoptosis after low-dose irradiation and large blood volume and dynamic blood flow within the RT fields could be somewhat related to lymphopenia after mediastinal irradiation.