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Prostate carcinogenesis in N-methyl-N-nitrosourea (NMU)-testosterone-treated rats fed tomato powder, lycopene, or energy-restricted diets.
J Natl Cancer Inst 2003; 95(21):1578-86JNCI

Abstract

BACKGROUND

Consumption of tomato products or lycopene and energy restriction have been hypothesized to reduce the risk of human prostate cancer. We investigated the effects of these dietary variables in a rat model of prostate carcinogenesis.

METHODS

Male rats (n = 194) treated with N-methyl-N-nitrosourea and testosterone to induce prostate cancer were fed diets containing whole tomato powder (13 mg lycopene/kg diet), lycopene beadlets (161 mg lycopene/kg diet), or control beadlets. Rats in each group were randomly assigned to either ad libitum feeding or 20% diet restriction. Differences between Kaplan-Meier survival curves for diet composition or restriction were tested with the log-rank test. Cox proportional hazards models were developed to examine the combined effect of diet composition and restriction on survival. Statistical tests were two-sided.

RESULTS

Risk of death with prostate cancer was lower for rats fed the tomato powder diet than for rats fed control beadlets (hazard ratio [HR] = 0.74, 95% confidence interval [CI] = 0.59 to 0.93; P =.009). In contrast, prostate cancer-specific mortality of the control and lycopene-fed rats was similar (P =.63). The proportions of rats dying with prostate cancer in the control, lycopene, and tomato powder groups were 80% (95% CI = 68% to 89%), 72% (95% CI = 60% to 83%), and 62% (95% CI = 48% to 75%), respectively. Rats in the diet-restricted group experienced longer prostate cancer-free survival than rats in the ad libitum-fed group (HR = 0.68, 95% CI = 0.49 to 0.96; P =.029). The proportion of rats that developed prostate cancer was 79% (95% CI = 69% to 86%) for ad libitum-fed rats and 65% (95% CI = 54% to 74%) for rats fed restricted diets. No interactions were observed between diet composition and dietary restriction.

CONCLUSIONS

Consumption of tomato powder but not lycopene inhibited prostate carcinogenesis, suggesting that tomato products contain compounds in addition to lycopene that modify prostate carcinogenesis. Diet restriction also reduced the risk of prostate cancer. Tomato phytochemicals and diet restriction may act by independent mechanisms.

Authors+Show Affiliations

Division of Nutritional Sciences, University of Illinois, Urbana-Champaign, IL (TWMB, JWE).No affiliation info availableNo affiliation info availableNo affiliation info availableNo affiliation info availableNo affiliation info available

Pub Type(s)

Journal Article
Research Support, U.S. Gov't, P.H.S.

Language

eng

PubMed ID

14600090

Citation

Boileau, Thomas W-M, et al. "Prostate Carcinogenesis in N-methyl-N-nitrosourea (NMU)-testosterone-treated Rats Fed Tomato Powder, Lycopene, or Energy-restricted Diets." Journal of the National Cancer Institute, vol. 95, no. 21, 2003, pp. 1578-86.
Boileau TW, Liao Z, Kim S, et al. Prostate carcinogenesis in N-methyl-N-nitrosourea (NMU)-testosterone-treated rats fed tomato powder, lycopene, or energy-restricted diets. J Natl Cancer Inst. 2003;95(21):1578-86.
Boileau, T. W., Liao, Z., Kim, S., Lemeshow, S., Erdman, J. W., & Clinton, S. K. (2003). Prostate carcinogenesis in N-methyl-N-nitrosourea (NMU)-testosterone-treated rats fed tomato powder, lycopene, or energy-restricted diets. Journal of the National Cancer Institute, 95(21), pp. 1578-86.
Boileau TW, et al. Prostate Carcinogenesis in N-methyl-N-nitrosourea (NMU)-testosterone-treated Rats Fed Tomato Powder, Lycopene, or Energy-restricted Diets. J Natl Cancer Inst. 2003 Nov 5;95(21):1578-86. PubMed PMID: 14600090.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - Prostate carcinogenesis in N-methyl-N-nitrosourea (NMU)-testosterone-treated rats fed tomato powder, lycopene, or energy-restricted diets. AU - Boileau,Thomas W-M, AU - Liao,Zhiming, AU - Kim,Sunny, AU - Lemeshow,Stanley, AU - Erdman,John W,Jr AU - Clinton,Steven K, PY - 2003/11/6/pubmed PY - 2003/12/3/medline PY - 2003/11/6/entrez SP - 1578 EP - 86 JF - Journal of the National Cancer Institute JO - J. Natl. Cancer Inst. VL - 95 IS - 21 N2 - BACKGROUND: Consumption of tomato products or lycopene and energy restriction have been hypothesized to reduce the risk of human prostate cancer. We investigated the effects of these dietary variables in a rat model of prostate carcinogenesis. METHODS: Male rats (n = 194) treated with N-methyl-N-nitrosourea and testosterone to induce prostate cancer were fed diets containing whole tomato powder (13 mg lycopene/kg diet), lycopene beadlets (161 mg lycopene/kg diet), or control beadlets. Rats in each group were randomly assigned to either ad libitum feeding or 20% diet restriction. Differences between Kaplan-Meier survival curves for diet composition or restriction were tested with the log-rank test. Cox proportional hazards models were developed to examine the combined effect of diet composition and restriction on survival. Statistical tests were two-sided. RESULTS: Risk of death with prostate cancer was lower for rats fed the tomato powder diet than for rats fed control beadlets (hazard ratio [HR] = 0.74, 95% confidence interval [CI] = 0.59 to 0.93; P =.009). In contrast, prostate cancer-specific mortality of the control and lycopene-fed rats was similar (P =.63). The proportions of rats dying with prostate cancer in the control, lycopene, and tomato powder groups were 80% (95% CI = 68% to 89%), 72% (95% CI = 60% to 83%), and 62% (95% CI = 48% to 75%), respectively. Rats in the diet-restricted group experienced longer prostate cancer-free survival than rats in the ad libitum-fed group (HR = 0.68, 95% CI = 0.49 to 0.96; P =.029). The proportion of rats that developed prostate cancer was 79% (95% CI = 69% to 86%) for ad libitum-fed rats and 65% (95% CI = 54% to 74%) for rats fed restricted diets. No interactions were observed between diet composition and dietary restriction. CONCLUSIONS: Consumption of tomato powder but not lycopene inhibited prostate carcinogenesis, suggesting that tomato products contain compounds in addition to lycopene that modify prostate carcinogenesis. Diet restriction also reduced the risk of prostate cancer. Tomato phytochemicals and diet restriction may act by independent mechanisms. SN - 1460-2105 UR - https://www.unboundmedicine.com/medline/citation/14600090/Prostate_carcinogenesis_in_N_methyl_N_nitrosourea__NMU__testosterone_treated_rats_fed_tomato_powder_lycopene_or_energy_restricted_diets_ L2 - https://academic.oup.com/jnci/article-lookup/doi/10.1093/jnci/djg081 DB - PRIME DP - Unbound Medicine ER -