CHAPTEE XVII 



THE CHEMISTRY OF TUMORS 



CHEMICAL investigations of tumors have been relatively few 

 in number, but, so far as they have yet been made, there has 

 been little detected that indicates any important deviation of 

 the chemical processes of tumors from those of normal cells of 

 similar origin. Likewise, the chemical composition of tumor 

 tissue resembles closely, on the whole, the composition of related 

 normal tissues. It is hardly to be imagined that the course of 

 chemical changes is greatly different in tumor cells from that in 

 normal cells, in view of the abundant evidence that the meta- 

 bolic products of tumor cells are identical with those of the cells 

 from which they arose. Thus, inetastatic growths of thyroid 

 tissue will produce thyroiodin in any part of the body, liver 

 carcinoma metastases produce bile, tumors from the choroid or 

 from pigmented moles produce melanin, etc. The capacity of 

 tumor cells to produce complicated products of metabolic action 

 specific for the parent cells from which they arose, as illustrated 

 above, indicates beyond question that the course of their chem- 

 ical activities is very much like that of normal cells. So, too, 

 the composition of the cells is found to be similar indeed to that 

 of the parent cells, both in regard to primary and secondary 

 constituents. Thus, Bang found that sarcomas derived from 

 lymph-glands contain the particular nucleoproteids that are found 

 normally only in lymph-glands ; hypernephromas contain, like 

 adrenal tissue, much fat, lecithin, and cholesterin ; squamous 

 cell carcinomas develop great amounts of kerato-hyalin ; carcino- 

 mas of mucous membranes may contain much mucin, etc. 



Many have sought in cancer tissues a poison that might 

 account for the cachexia charateristic of new-growths. Extracts 

 have been obtained that were destructive to red corpuscles 

 (hemolytic), and that were sometimes slightly toxic to animals, 

 but the results have not seemed sufficiently striking to account 

 for the appearance of cachexia. Because of the interference 

 with circulation, brought about in tumors by pressure of the 

 growing tissues upon their blood-vessels, areas of necrosis fre- 

 quently develop, and these, undergoing autolysis, yield substances 



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