Elsevier

Urology

Volume 64, Issue 4, October 2004, Pages 765-771
Urology

Adult urology
Prostate cancer in native Japanese and Japanese-American men: Effects of dietary differences on prostatic tissue

https://doi.org/10.1016/j.urology.2004.05.047Get rights and content

Abstract

Objectives. To investigate the relationship between diet and prostate cancer (CaP) among native Japanese (NJ) and second-generation or third-generation Japanese-American (J-A) men—focusing on the effects of animal fat and soy on prostatic tissues.

Methods

The subjects were 50 Japanese men undergoing radical prostatectomy, 25 NJ living in Nagoya, Japan and 25 U.S.-born J-A men, living in Los Angeles, California. A priori, the NJ men were believed to be a low-fat, high-soy group and the J-A men, a high-fat, low-soy group. The studies included postoperative measurements of diet (Block questionnaire), body fat (bioimpedance), blood, urine, and prostatic biomarkers in malignant and adjacent normal tissue, using a tissue microarray made from the original paraffin blocks.

Results

The NJ and J-A men were similar in age (65 to 70 years old; P <0.05), prostate-specific antigen level (7.1 to 8.6 ng/mL), prostate volume (35 to 38 cm3), and Gleason score (5.6 to 6.6), but their body composition differed. J-A men had more body fat (24% versus 19%), higher serum triglyceride levels (245 versus 106 mg/dL), lower estradiol levels (27 versus 31 ng/mL), and much lower urinary soy-metabolite levels (1:3) than NJ men (P <0.02). In both NJ and J-A groups, expression of numerous tissue biomarkers separated normal from CaP tissue, including markers for apoptosis (Bcl-2, caspase-3), growth factor receptors (epidermal growth factor receptor), racemase, 5-lipoxygenase, kinase inhibition (p27), and cell proliferation (Ki-67; all P <0.02). Furthermore, within both normal and CaP tissues, caspase-3 and 5-lipoxygenase were expressed more in NJ than in J-A men (P <0.01). Nuclear morphometry showed that the chromatin in each of the four groups (normal versus CaP, NJ versus J-A) was different (area under the curve 85% to 94%, P <0.01), despite fundamental genetic homogeneity.

Conclusions

NJ and J-A men, products of similar genetics but differing environments, were shown to have differences in body composition that could influence CaP evolution. The CaP specimens from the NJ and J-A men were histologically similar, but tissue biomarker expression, especially of lipoxygenase and the caspase family, suggested differing mechanisms of carcinogenesis. Differences in nuclear morphometry suggested the additional possibility of gene-nutrient interactions.

Section snippets

Material and methods

A retrospective study of 50 Japanese men undergoing radical prostatectomy for cure of localized CaP between 1994 and 2001 was performed. All 50 men had typical Japanese surnames, and each regarded himself as of pure Japanese ancestry. Of the 50 men, 25 were Japanese-born men undergoing surgery in Nagoya, Japan, and 25 were second-generation or third-generation American-born Japanese men undergoing surgery in Los Angeles, California. Each series was consecutive and included all qualifying

Clinical characteristics

The men in this study were mostly in their mid to late 60s with moderately differentiated, organ-confined CaP (Table I). The J-A men were, on average, 5 years older (70 years versus 65 years), had a greater percentage of body fat (24.2% versus 19.3%), and underwent surgery 28.2 months earlier than the NJ men (P <0.002). Otherwise, the two groups were similar in terms of prostate weight (38.5 to 34.8 g), serum prostate-specific antigen level (7.1 to 8.6 ng/mL), pathologic tumor stage (mostly

Comment

The main hypothesis of the present study was that Western diet leads to tissue changes associated with malignant transformation in the prostate. Thus, two groups of men were studied, all with CaP and all from the same gene pool (all Japanese), but ingesting diets traditionally known to be markedly different. Although the dietary questionnaire did not reveal dramatic differences between the NJ and J-A men, their body composition was found to be different in several important ways, and related

Acknowledgment

To Maria Luz Macairan, M.D., Arlyn Llanes, and Shamim Baker, who provided research coordination at the Urological Sciences Research Foundation; Matthew Putzi, M.D., Helen Fedor, and the staff at the Johns Hopkins Tissue Microarray Laboratory, who constructed the tissue microarray; Massood A. Khan of the Brady Urological Institute for performing the QNG image analysis; George Yamauchi, M.D., and Yuichi Ito, M.D., who contributed the Los Angeles patients from their urology practices; George

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    This study was supported by grants from CaPCURE, The Prostate Cancer Foundation, Santa Monica, California; Elsa U. Pardee Foundation, Midland, Michigan; UCLA Clinical Nutrition Research Unit, grant CA 42170 to D. Heber; NCI grant P01-CA77739 to J. L. Mohler; Early Detection Research Network, NCI grant U01CA86323 and NCI Spore grant P50CA58236 to A. W. Partin.

    This study was presented in part at the Annual Meeting of the American Urological Association, Chicago, Illinois, April, 2003, and at the Annual Retreat of the CaPCURE Foundation, Washington, DC, September 2002.

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