Irradiation influence on the bone marrow function of patients who received external radiotherapy to the bone metastasis lesion

The effects of external radiotherapy (EBRT) on the bone marrow function were studied in 49 patients who received regional EBRT to the bone metastatic lesions. The platelet counts showed gradual but significant decrease to 88.0% at 12 weeks after completing the irradiation compared to the baselines. The lymphocyte counts decreased rapidly and significantly to 74.3% at 2 weeks after starting the irradiation but recovered to the baseline levels at 12 weeks after the irradiation. The decreases in the lymphocytes showed weak correlations with the widths of the irradiation areas and the lymphocytes counts before the irradiation, respectively. There found no significant decrease in the other blood cell counts which provoked serious adverse events due to the EBRT. These results suggest that the regional irradiation to the bone metastatic lesions would not cause serious nor long-term myelosuppression. (author)