Cancer and the radiotherapist.

THE first cure of skin cancer with ionizing irradiation was reported in I899. Within a few years the new rays had been tried out on many disease processes, including deep tumours. Cures of superficial, accessible cancers were reported in increasing numbers, but at the same time complications followed the use of the new rays. These included the production of cancer. By the 1930s radium and radon were established firmly in the radiotherapist's armamentarium and so-called deep 200to 25o-kilovolt X-rays were in general use for the external treatment of cancer. Experiences with a few small 'Io-g. radium 'bomb' units and one or two higher voltage X-ray machines indicated that better results might be obtainable with external irradiation using harder, more penetrating rays. It has recently become practical clinically to produce supervoltage X-rays from cyclical or linear accelerators, and an additional impetus has been given to radiotherapy by the availability of 60Co sources, emitting a gamma-ray beam equivalent to X-rays from a machine of between 2 and 3 million volts. Other techniques that have been investigated enthusiastically over the last few years include rotation therapy, charged particle irradiation, isotopic replacements for radium and radon, and the chemical or biological modification of the radiation response. Probably the most encouraging recent tendency has been the increasing co-operation between the radiotherapist and all other branches of medicine. Combined clinics are becoming accepted features of medical practice, with considerable benefit to the patient. Only in this way will radiotherapists continue to improve their results.