Fundamental and clinical studies on cancer control with total or upper half body irradiation

The tumor control effects of total body irradiation (TBI) for tumor bearing mice and human tumor were investigated fundamentally and clinically. TBI is usually used in tissue transplantation experiment in order to prevent rejective response for transplanted tissues by immunological reaction. This kind of suppressive effect of immunological response by TBI is considered as to be caused even if very small dose of TBI. However, there are only a few data concerning the effect of low dose of TBI, and TBI of low dose level is concluded to bring about the same effect as in high dose level by back extrapolation from the data of high dose level. In present paper, firstly the effects of TBI for tumor control in murine squamous carcinoma are reported, and secondly the results of clinical trial in malignant lymphoma are demonstrated. In fundamental studies, TBI of low doses (10-15 cGy) suggests potentiating effect in cell killing in combination of TBI of 10 cGy and local irradiation given at 12 hours after TBI though TBI of 10 cGy is not able to detect any cell killing effect. TBI of 10 cGy or 15 cGy also stands for suppressive effect of distant metastasis (lung metastasis). In clinical studies, malignant lymphoma (non-Hodgikin's lymphoma) is selected as the first disease of clinical trial, and the results are seemed to be prospective method to overcome cancers with radiotherapy, though the trial is not phase III clinical trial. (author)