DISCUSSION ON TUMOR RESPIRATION 235 



ON THE SPECIFICITY OF GLYCOLYSIS IN MALIGNANT 



LIVER TUMORS AS COMPARED WITH HOMOLOGOUS 



ADULT OR GROWING LIVER TISSUES* 



DEAN BURK 



National Cancer Institute, National Institute of Health, U. S. Public Health 



Service, and Cornell University Medical College 



In this discussion I wish to focus attention upon one particular 

 aspect of tumor and growth metabohsm that is simple but far- 

 reaching in implication. It is a problem more of comparative bio- 

 chemistry than of intermediate metabolism proper, and concerns 

 the origin of tumor metabolism. The question I wish to pose, and 

 hope to succeed in answering here, is whether the large glycolysis 

 of tumors is necessarily an expression and requirement of their 

 extensive and usually rapid growth. It has been widely held, since 

 the middle period of Warburg's tumor work (1925), that growing 

 tissues in general have a high anaerobic (and sometimes aerobic) 

 glycolytic activity. This very active metabolism has in turn been 

 attributed to extra and special metabolic requirements of the growth 

 process. If it could be found that certain growing tissues do not 

 exhibit marked glycolysis, then it might well be said that the glycol- 

 ysis of tumors is not necessarily a consequence merely of extensive 

 growth, but that it has a more specific and characteristic significance 

 for tumor metabolism than has been recognized or acknowledged. 



Before presenting data bearing directly on the foregoing question, 

 a related aspect of the problem of the origin of tumor glycolysis, and 

 of suitable criteria for ascertaining significant differences between 

 normal and tumor metabolism, should be discussed by way of back- 

 ground (cf. also ref. 17). In recent years Berenblum, Chain, and 

 Heatley (1) have made the claim that "valid comparisons can only 

 be made between any particular tumor and the normal tissue from 

 which it is derived" (la, p. 370). This emphatic assertion, which I 

 believe it is very desirable to contravert at this early stage in its 

 possible development, is surely dogmatic and arbitrary to say the 

 least, for there are many valuable comparisons to be drawn between 

 tumor materials and adult tissues widely separated from them 

 embryologically, as well as between tumors and tissues as closely 

 homologous as possible. I for one would not undertake to say which 

 type of comparison would, in fact, be the more profitable in the 

 long run, let alone advocate the exclusion of either one. Certainly 



* For much valuable help in the preparation of this manuscript I am greatly 

 indebted to Miss Juliet M. Spangler, Senior Cancer Aide, 



