Clinical Experience With Split-Course Radiotherapy

Citations Over TimeTop 10% of 1969 papers

Abstract

IMPROVEMENT in results of cancer radiotherapy during recent years is due more to the fact that patients now seek treatment at an earlier stage of the disease than to true progress in treatment. Megavoltage therapy has, of course, meant indubitable progress—and the results in some tumor groups have improved because of it—but the better results depend on physical benefits and bigger dose. The essential problems of radiotherapy, on the other hand, are of a biological nature. The most important of these are the tumor characteristics and the proper utilization of the biological effects of irradiation. The recent advances in radiobiological research have greatly stimulated clinical radiotherapy. The aim of radiotherapy is practical; its achievement requires observation in the field of basic research, and, on the other hand, clinical therapy repeatedly poses new problems for radiobiology. Testing the validity of the observations and hypotheses of experimental radiobiology in clinical work is a task for radiotherapists. Fractionation is an important problem to both biologist and therapist, and splitcourse radiotherapy represents one form of the newer fractionation regimes. Here the treatment is divided into two or perhaps more phases separated by a rest interval. The theoretical basis of this therapy is the difference in cell proliferation between normal and tumor cells (23). During the rest interval, normal tissue proliferates as a result of cell loss stimulating the homeostatic feedback, inducing rapid proliferation. In malignant cells stimulation like this fails, and there is very little regrowth during a rest interval of two to three weeks. This method has been used by Sambrook in England and by Scanlon in the United States for many years. We have employed it increasingly in Helsinki since 1963. As early as 1935 Coutard (5) discussed the value of repeated short series of radiotherapy. Zuppinger (34, 35) was the first to use radiotherapy in two phases in treating patients with advanced cancer of the hypopharynx. Planned splitting of the radiotherapy course was reported by Sambrook in 1959 (21). A retrospective study of the effect of unplanned interruption of radiotherapy was reported in 1959 by Scanlon (25) and in 1964 by Holsti and Taskinen (14). In both studies it was concluded that interrupted treatment might be more favorable than continuous daily irradiation. Afterward, prospective clinical experiences confirmed the preliminary results of retrospective studies (9–12, 15, 22, 24, 26–32). Dutreix et al. (7) presented a modification of the treatment, in which the first part of the split-course therapy is given in two large fractions and the second part is fractionated as daily treatment or three times weekly. Both phases of the treatment have been given as a few large fractions by Levitt et al. (18).

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