[Changes in the content and composition of gangliosides of tumors as affected by chemotherapeutic agents]. 
The lipid-bound sialic acid (LSA) levels increased in the metastasizing Lewis lung carcinoma (3LL) and significantly decreased in blood plasma of the tumour-bearing mice after cyclophosphamide treatment correlating with the drug therapeutic effect.  5-fluorouracil that was less active in the used therapeutic doses did not cause similar changes in the LSA levels.  No correlation was found between the LSA levels in adenocarcinoma 755 and the drug antitumour activity.  It was observed that the content of hematoside, GM1 and GD1b sharply increases and GD3 and GD1a levels significantly decrease under the cyclophosphamide treatment of the Lewis tumour.