The effect of carbohydrate restriction on prostate cancer tumor growth in a castrate mouse xenograft model

BACKGROUND No- and low-carbohydrate diets delay tumor growth compared to western diet (WD) in prostate cancer (PCa) xenograft studies. The effect of these diets in concert with androgen deprivation is unknown. METHODS A total of 160 male SCID mice were injected with 1x 105 LAPC-4 human PCa cells. Of these, 150 mice were castrated and randomized to an ad libitum WD or fed via a paired-feeding protocol with a no-carbohydrate ketogenic diet (NCKD), 10% carbohydrate diet, or 20% carbohydrate diet. The remaining 10 mice were not castrated and were fed an ad libitum WD. The mice were sacrificed once volumes reached 1,000mm3 and survival tested using the log-rank test. Serum from the median surviving 8mice/group was assayed for insulin, IGF-1, and IGFBP-3. RESULTS Body weights were roughly equal among groups. The 10 non-castrated mice experienced accelerated tumor growth. Among castrated mice, WD had the most rapid tumor growth; 20% carbohydrate diet the slowest (P=0.046). Survival was not significantly different among the various carbohydrate restricted groups (P=0.51). When pooled, there was a non-significant trend (P=0.11) in improved survival among the carbohydrate restricted diets versus WD. No significant difference in serum insulin, IGF-1, and IGFBP-3 levels was noted among all groups at pre-randomization or at sacrifice. CONCLUSIONS A 20% carbohydrate diet slowed tumor growth versus a WD. Though the benefit of carbohydrate restriction was somewhat less than in prior studies in non-castrate mice, these data still suggest diets achievable in humans may play a role in PCa management. Prostate 73: 449454, 2013. (c) 2012 Wiley Periodicals, Inc.