THE INFLUENCE OF RADIATION ON THE SURVIVAL 

 OF MICE INJECTED WITH ASCITES TUMOUR CELLS 



V. DKASIL 



Institute of Biophysics, Czechoslovak Academy of Sciences, Brno, Czechoslovakia 



If Elirlich ascites tumour cells (EAT) are injected otherwise than intra- 

 peritoneally, there arise solid tumours, the localization of which depends on 

 the manner of injection. After intravenous injections of EAT, the tumours 

 develop mostly in the lungs, less frequently in the mesentery, liver and other 

 organs. 



In this communication we present the results of preliminary experiments 

 aimed at finding an answer to the question of whether the irradiation of the 

 animal prior to injecting it with EAT can influence the resulting formation 

 and growth of tumours. 



The diploid form of EAT grows in mice of all strains hitherto tested 

 in this respect (CBA, C3H, C57B1, ASW). Non-irradiated mice (three- 

 month-old females) die after an injection of 10 million cells, their mean 

 survival-time being about thirty days. The mean survival-time depends on 

 the number of injected cells; when 1 million ceUs are injected, it amounts to 

 forty-five days. Tumours are found uniformly in aU experimental animals 

 after an intrajDeritoneal injection. It appears that the injected cells produce a 

 very weak homologous reaction. The EAT for our experiments with intra- 

 venous injections was obtained from the peritoneal cavity of mice through 

 which the tumour is passed. The suspension for intravenous injections was 

 diluted at least ten times and injected very slowly in an amount of 0-8 ml. 



The experimental mice were divided into three groups, viz. non-irradiated, 

 irradiated one day prior to injection with EAT, and irradiated thirty days 

 before being injected. The mice were given doses of 20 r, 60 r, and 180 r 

 (180 kV, 0-5 mm Cu, 1-0 mm Al). The results of one typical experimental 

 series are shown in Fig. 1. From these results it follows that, after an injection 

 of EAT, irradiated mice die much faster than non-irradiated ones. Upon 

 repeating the experiments we have found a good reproduceabUity after doses 

 of 60 r and 180 r. In mice irradiated with 20 r, the reduction of the mean 

 survival time after an injection of EAT lies on the borderline of statistical 

 significance. 



From the results of these experiments it follows that even small doses of 

 radiation can exert such an influence on mice that from the EAT injected 

 into them intravenously tumours are formed at a faster rate, and consequently, 



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