The effect of added dietary tryptophane on the occurrence of diethylstilbestrol-induced mammary cancer in rats
Dunning, W.F.; Curtis, M.R.; Maun, M.E.
Cancer Research 10(5): 319-323
1950
ISSN/ISBN: 0008-5472 PMID: 15414482 Document Number: 518870
Three groups of A x C Line 9935 female rats with diethylstilbestrol pellets implanted in their scapular region, were placed on iso-caloric synthetic diets containing 26% protein. The 1st group of 12 received the diet with 26% casein, the 2d group of 12 received the same diet, substituting 24.6% tryptophan-free casein hydrolysate and 1.4% D, L-tryptophan for the intact casein and the 3d group of 15 received in place of the intact casein, 21.7% tryptophan-free casein hydrolysate, plus 4.3% D, L-tryptophan. All 39 rats lived more than 160 days, the minimum period before the occurrence of an induced mammary cancer, and 32 or 82% developed multiple mammary cancers. Of the control group, 9 or 75% developed 51 gross cancers in an average of 363 ± 8.6 days, while 100% of those which received 1.4% D, L-tryptophan developed 79 mammary cancers in an avg. of 316 ± 5.7 days and 9 or 60% of the rats that received the high-tryptophan diet developed only 31 gross mammary cancers in an avg. of 399 ± 7.5 days. Addition of 1% D, L-tryptophan in-creased the number and % of induced cancers and significantly reduced the avg. latent period below that observed for the control group. The greater increase in dietary tryptophan produced the reverse effect of a decreased number and percentage of induced cancers and a significantly prolonged latent period.