ABSTRACT
The neutron beam has higher relative biological effectiveness (RBE) than conventional X or gamma ray because it is densely ionizing radiation which is presented by high linear energy transfer (LET). This physical and radiobiological characteristic plays an important role in killing of cancer cells in the state of biologically radio-resistant to the conventional radiation. The rationale of high LET radiation in the application to clinical radiotherapy is summarized as, high oxygen enhancement ratio (OER), less repair of cell damage, and less dependence of radio-sensitivity on cell cycle. Neutron therapy alone or combined with conventional radiotherapy was performed in 12 patients with stage C or D1 prostatic cancer from Mar. 1987 to Dec. 1989 in Korea Cancer Center Hospital. Local control rate at the time of 24 months after therapy was 67% (4/6) in stage C and 67% (4/6) in stage DI. Two-year actuarial survival rate after therapy was 82% in stage C and 67% in stage D1. The problem of neutron therapy was relatively high incidence of major complication rate, but it could be lessened by the accumulation of experience for neutron therapy. We think neutron therapy to be one of adequate treatment modalities for local control of stage C or Dl prostatic cancer.