134 Action of Radium and X-Rays upon Tumour Growth. 



growth of tumour, viz., 1-46 times the normal, the number of animals 

 being seventeen (vide Table lY). 



The data in Section B (Table II) show that the body weight of the rat 

 increases 15 per cent, more rapidly under small dose X-ray treatment than 

 that of untreated animals of the same initial body weight ; the number of 

 animals used is enough to preclude the effect being accidental. 



The increased resistance to tumour inoculations of an animal which has 

 previously been given small daily doses of X-rays is a fairly constant 

 feature of Table III. Considering the number of animals used (viz., 77, 

 and an equal number of controls), it is very improbable that the reduction 

 in tumour growth, amounting on the average to about 40 per cent., can 

 be attributed to anything but the X-ray treatment. 



In Section C, Table V, the quantitative reduction in the rate of tumour 

 growth appears to be sufficiently large to preclude the element of chance. 

 There is less restraint upon the growth of the tumour when the tumour itself is 

 allowed to share in the small-dose radiation treatment {vide data in Table VI). 



The bearing of these investigations upon the radiological treatment of 

 malignant disease in man appears to be two-fold. In the first instance 

 it must be recognised that the uniform irradiation of a large tumour in 

 the human subject is hardly possible whether X-rays or radium be used. 

 Small variations from the lethal dose would appear imimportant, but 

 should the quantity of radiation reaching outlying portions of the growth 

 be so diminished in intensity as to be a small dose (such as a few per cent, 

 of the lethal dose) it might have a stimulating instead of a destructive effect 

 on the malignant cells. Turning now to the body as a whole, there seems 

 ample evidence to show that large generalised doses of radiation lower 

 the normal resistance to tumour growth. This result is completely reversed 

 when the normal animal is given very small generalised doses of X-rays, 

 repeated at frequent intervals, and it would therefore seem a rational 

 measure to supplement the local intensive irradiation of a tumour by a 

 feeble generalised irradiation of the patient, care being taken wherever 

 possible not to expose the tumour cells to this radiation. 



EEFERENCES. 



1. Chambers, Scott and Euss, ' Journal of Pathology and Bacteriology,' vol. 23, 1920. 



2. Wedd and Euss, 'Journal of Pathology and Bacteriology,' vol. 17 (1912). 



3. Wood and Prime, ' Annals of Surgery,' vol. 62, p. 751 (1915). 



4. Euss, Chambers, Scott and Mottram, ' Lancet,' April 28, 1919. 



5. Murphy and Morton, 'Journal of Experimental Medicine,' vol. 22 (1915). 



6. Mottram and Euss, ' Eoy. Soc. Proc.,' B, vol. 90 (1917). 



7. Prime, 'Journal of Cancer Eesearch,' p. 115, April, 1920. 



