Decreased growth of human prostate LNCaP tumors in SCID mice fed a low-fat, soy protein diet with isoflavones.

Epidemiological studies suggest that high intake of dietary fat is a risk factor for the development of clinical prostate cancer. Soy protein has also been proposed to play a role in the prevention of prostate cancer, and one of the isoflavones in soy protein, genistein, inhibits the growth of human prostate cancer cell lines in vitro. This study was de-signed to evaluate whether altering dietary fat, soy protein, and isoflavone content affects the growth rate of a human androgen-sensitive prostate cancer cell line (LNCaP) grown in severe-combined immunodeficient (SCID) mice. SCID mice were randomized into four dietary groups: high-fat (42.0 kcal%) = casein, high-fat (42.0 kcal%) = soy protein = isoflavone extract, low-fat (12.0 kcal%) = casein, and low-fat (12.0 kcal%) = soy protein = isoflavone extract. After two weeks on these diets, the mice were injected subcutaneously with 1 = 10 5 LNCaP tumor cells and placed in separate cages (1 mouse/cage) to strictly control caloric intake. Isocaloric diets were...