Clinical results with fast neutrons (DT, 14 MeV).

In Hamburg, the therapy with DT-neutrons had the best curative effect on highly differentiated tumors. With the standard dose of 15.6 Gy in four weeks with fast neutrons only or--in treating tumors in radiosensitive organs such as brain and intestine--with a photon-neutron schedule, we have seen no necroses in normal tissues. The rate of medium or slight subcutaneous fibroses has been no more than 10%. The local effect on tumors in our pilot study has been better than with megavoltage therapy in invasive thyroid cancer, prostate cancer stage C, soft tissue sarcoma, and rectal carcinoma. The best results have been achieved with neutrons only, but a photon-neutron schedule may be more effective as megavoltage therapy only. With our DT-neutrons we find some indications for better results than with megavoltage therapy if we use sophisticated treatment planning and if we strictly observe the tolerance dose of the different tissues and organs. The therapeutic index of our DT-neutrons is higher than with cyclotron-produced neutrons.