The Effect of Cod-Liver Oil on Tumor Growth

Abstract

Introduction Sugiura and Benedict (1925) fed cod-liver oil and various vegetable oils and found them without influence on the percentage of takes obtained or on the rate of growth of the Flexner-Jobling rat carcinoma or the Bashford and Twort mouse carcinoma. Preliminary experiments in connection with the effect of dietary fats on growth and composition of tumors (Haven, 1935) had indicated that cod-liver oil inhibits the growth of a rat carcinosarcoma. This fact is further substantiated in the present paper. Experimental Tumor: The tumor used throughout the subsequent experiments was rat carcinosarcoma 256 obtained from the Institute of Cancer Research, Columbia University. Young male rats weighing from 70 to 100 gm. were inoculated subcutaneously in the groin by the trocar method. In each of the experiments all the rats were inoculated from the same tumor. Diets: The diet used was Diet Number 262 (Sinclair, 1931) having the following percentage composition: The fats used were cod-liver oil of iodine number 157 and, for comparison, coconut oil of iodine number 9. When coconut oil was fed, vitamins A and D were supplied by dissolving the unsaponifiable matter from 5 gm. of cod-liver oil in each 100 gm. of fat. In each of the experiments half of the rats were placed on the cod-liver oil diet and half on the coconut oil diet on the day of inoculation and kept on this diet until the tumors were removed. Measurement of Tumor Growth: The method of measurement of tumor growth involved weighing the tumor at the time of removal from the animal which, in the majority of cases, was from five to seven weeks after inoculation. To permit comparison of the growth of a tumor of one age with that of a tumor of another age, the growth tendency of each tumor has been calculated by means of a formula of Bierich and Lang (1933) involving the weight of the tumor in grams upon its removal from the rat and its age in days from the date of inoculation, namely, Wt.=a.t2; a (growth tendency of the tumor) = weight/time2 × 10,000.