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On the Local and Generalised Action of Radium and X-Rays 

 upon Tumour Growth.* 



By S. Euss, D.Sc, Helen CHAiiBERS, M.D., and Gladwys M. Scott, Cancer 

 Eesearch Laboratories, Middlesex Hospital. 



(Communicated by Sir Walter Fletciier, F.E.S. Eeceived December 31, 1920.) 



There are many considerations in the successful treatment of a tumour in 

 the animal body by radiation. Broadly speaking, the subject may be divided 

 into two main divisions : (1) the action of X-rays and the beta- and gamma- 

 rays from radium on the tumour cells, and (2) the effect of these rays upon 

 the animal itself. 



In both cases a gradual change of effects is observed according to the 

 dose of radiation. Actively growing malignant cells, given a large dose of 

 radiation, degenerate and die when re-inoculated into a living animal ; a dose 

 short of this quantity causes the tumour cells to grow at a slower rate 

 than they would do normally, but if given a very small dose, the cells appear 

 to be stimulated rather than hindered in their subsequent growth. 



Prolonged exposure of the animal to the rays results in severe wasting 

 .and death ; with a reduction in the exposure a growing animal will retain its 

 health, but with a diminished rate of increase of body weight. As the dose 

 of radiation becomes less, a stage is reached when the rate of increase of 

 body weight exceeds that of the normal animal ; and, when the animal 

 is given these very small doses of X-rays, it is found to develop a state of 

 increased resistance to an implanted tumour. 



Such briefly are the chief effects to be considered when devising methods 

 by which a lethal dose of radiation may be given to a tumour without 

 reducing the resistance of the animal. 



The experimental data in this paper will be dealt with as follows : — 



(A) The effect of the rays in various doses upon mahgnant cells, before 

 inoculation. 



(B) The effect of the rays in various doses upon normal animals — (1) body 

 growth, and (2) subsequent inoculations of mahgnant cells. 



(C) The effects of the rays in various doses upon animals which are 

 bearing tumours. 



This investigation has been carried out upon rats, and the tumours have 

 been of three distinct types : Jensen's rat sarcoma ; a very slowly growing 



* This investigation includes, though is not restricted to, experimental work under- 

 taken at the request of the Medical Eesearch Council upon the general biological effects 

 of small doses of X-rays. 



