[Fast neutron radiotherapy of prostate cancer]

Between 1976 and 1987, sixty eight patients suffering from prostate cancer were treated with fast neutron radiotherapy at the NIRS hospital in Chiba, Japan. Tumor doses of TDF 100 were administered to the prostate gland, the regional lymphnodes, and the true pelvis, using the two opposing fields by fast neutron alone or with a boost. The overall local or regional tumor recurrence rate was found to be 10% and local control seemed to correlate with the histological differentiation of the cancer tissue, though there was no definite correlation with hormone treatment. A relatively high incidence of grade 3 and 4 radiation complications were observed, 21% for grade 3 and 7% for grade 4, due to subcutaneous fat necrosis caused by an inferior dose distribution of the fast neutron machine. The 5-year survival rate was seen to be 52% in total and 70% for patients in stage C. The modality of radiotherapy for prostate cancer is discussed.