The consumption of diets containing 5 to 10 servings of fruits and vegetables daily is the foundation of public health recommendations for
cancer prevention, yet this concept has not been tested in experimental models of
prostate cancer. We evaluated combinations of tomato and broccoli in the Dunning R3327-H prostate
adenocarcinoma model. Male Copenhagen rats (n=206) were fed diets containing 10% tomato, 10% broccoli, 5% tomato plus 5% broccoli (5:5 combination), 10% tomato plus 10% broccoli (10:10 combination) powders, or
lycopene (23 or 224 nmol/g diet) for approximately 22 weeks starting 1 month prior to receiving s.c.
tumor implants. We compared the effects of diet to surgical
castration (2 weeks before termination) or
finasteride (5 mg/kg
body weight orally, 6 d/wk).
Castration reduced prostate weights,
tumor areas, and
tumor weight (62%, P<0.001), whereas
finasteride reduced prostate weights (P<0.0001), but had no effect on
tumor area or weight.
Lycopene at 23 or 224 nmol/g of the diet insignificantly reduced
tumor weights by 7% or 18%, respectively, whereas tomato reduced
tumor weight by 34% (P<0.05). Broccoli decreased
tumor weights by 42% (P<0.01) whereas the 10:10 combination caused a 52% decrease (P<0.001).
Tumor growth reductions were associated with reduced proliferation and increased apoptosis, as quantified by
proliferating cell nuclear antigen immunohistochemistry and the ApopTag assay. The combination of tomato and broccoli was more effective at slowing
tumor growth than either tomato or broccoli alone and supports the public health recommendations to increase the intake of a variety of plant components.