[Present trends in cancer therapy with high-LET radiations]

Application of high-LET radiations in cancer therapy is based on radiobiological arguments : great efficiency against hypoxic cancer cells, or cells in resistant phases of the mitotic cycle or quiescent. However, from a clinical point of view, the problem of the selection of patients who could benefit from high-LET radiations is not solved. Clinical observation shows that high-LET radiations bring a benefit for certain types of rumours : salivary glands, antrum, prostate, sarcomas, etc. These rumours are, in general, slowly growing, well differentiated and resistant to conventional x-rays as well as chemotherapy. Among high-LET radiations, fast neutrons have been most widely used. Today, neutrons can be applied in technical conditions, and with a allow the radiotherapist to apply high-LET radiations with an excellent physical selectivity. Unfortunately, the complexity of the equipment and mainly the cost prevented the development of the technique.