Effects of essential fatty acid deficiency and of carbon tetrachloride-induced liver cirrhosis on oral carcinogenesis in the rat.

The relative resistance of the oral mucosa to carcinogenic influences was studied in connection with altered fatty acid composition of the oral epithelium in the rat. The water-soluble carcinogen 4-nitrochinoline N-oxide was used. The lipid changes were induced either through essential fatty acid (EFA) deficiency or through carbon tetrachloride-induced liver cirrhosis. Although the strongest initial reaction in the oral mucosa was seen in the EFA-deficient rats, a result considered to be due to increased permeability of the epithelium to the carcinogen, oral carcinoma did not develop earlier in the EFA-deficient group than in normal controls. The liver cirrhotic group developed clinical signs of carcinoma earliest (5.4 months) whereas in EFA-deficient and normal rats carcinoma appeared after an average of 6.0 and 6.5 months, respectively. However, as a previous study (Lekholm 1976) has shown that the fatty acid changes were less pronounced in cirrhotic than in EFA-deficient rats, it would appear that there is no clear correlation between the extent of lipid distrubance and reduced resistance of the oral epithelium to the induction of carcinoma.