Potent preventive action of curcumin on radiation-induced initiation of mammary tumorigenesis in rats

This investigation evaluated the preventive effect of curcumin on radiation -induced tumor initiation in rat mammary glands. Fifty-four female rats wer e mated and then divided into two groups at day 11 of pregnancy. As the con trol group, 27 rats were fed a basal diet during the experimental period. A s the experimental group, 27 rats were fed a diet containing 1% curcumin be tween day 11 of pregnancy and parturition (day 23 of pregnancy). All rats o f both groups received whole body irradiation with 1.5 Gy gamma -rays from a Co-60 source at day 20 of pregnancy and were then implanted with a diethy lstilbestrol pellet 1 month after weaning. A high incidence (70.3%) of mamm ary tumorigenesis was observed in the control group. The tumor incidence (1 8.5%) was significantly reduced in the rats fed curcumin during the initiat ion stage. The appearance of the first palpable tumor was delayed by 6 mont hs in the curcumin-fed group and the average latent period until the appear ance of mammary tumors was 2.5 months longer in the curcumin-fed group than in the control group. By histological examination, the proportion of adeno carcinoma (16.7%) in total tumors in the curcumin-fed rats was found to be decreased to half that (32.1%) in the control group. Compared with the cont rol rats, the body weight of rats in the experimental group was decreased s lightly by administration of the curcumin diet from day 11 of pregnancy, in spite of a similar intake of diet, but had recovered to the level of the c ontrol by the end of the experiment. At the time of irradiation, curcumin d id not have any effect on organ weight or on the development and differenti ation of mammary glands of pregnant rats. In addition, the serum concentrat ions of fatty acids, thiobarbituric acid-reactive substances and ovarian an d pituitary hormones, except LH, remained at the control level. Also, mo ch ange in litter size and body weight of pups born from curcumin-fed rats ind icated no toxicity of curcumin, These results suggest that curcumin does no t have any side-effects and is lan effective agent for chemoprevention acti ng at the radiation-induced initiation stage of mammary tumorigenesis.