Dietary selenium intake and growth of the MT-W9B transplantable rat mammary tumor.

The present study reports the effect of dietary selenium deficiency and supplementation on the growth of the transplantable MT-W9B mammary tumor in female Wistar-Furth rats. Supplementation of the diet with 2 ppm of selenium inhibited tumor growth and reduced the final tumor weight by approximately 50% compared to the control rats receiving 0.1 ppm of selenium. The inhibitory response was selective, without inducing any weight loss in the animals. On the other hand, selenium deficiency (less than 0.02 ppm) had no influence on the growth of this tumor.