Soy product and isoflavone consumption in relation to prostate cancer in Japanese men.

The incidence of prostate cancer is much lower in Asian than Western populations. Environmental factors, such as dietary habits, may play a major role in the causation of prostate cancer. Although isoflavones have been suggested to show a preventive effect against prostate cancer in animal experiments, the results of epidemiologic studies are inconsistent. Here, we conducted a population-based prospective study in 43,509 Japanese men ages 45 to 74 years who generally have a high intake of isoflavones and low incidence of prostate cancer. Participants responded to a validated questionnaire, which included 147 food items. During follow-up from 1995 through 2004, 307 men were newly diagnosed with prostate cancer, of which 74 cases were advanced, 220 cases were organ localized, and 13 cases were of an undetermined stage. Intakes of genistein, daidzein, miso soup, and soy food were not associated with total prostate cancer. However, these four items decreased the risk of localized prostate cancer. In contrast, positive associations were seen between isoflavones and advanced prostate cancer. These results were strengthened when analysis was confined to men ages >60 years, in whom isoflavones and soy food were associated with a dose-dependent decrease in the risk of localized cancer, with relative risks for men in the highest quartile of genistein, daidzein, and soy food consumption compared with the lowest of 0.52 [95% confidence interval (95% CI), 0.30-0.90], 0.50 (95% CI, 0.28-0.88), and 0.52 (95% CI, 0.29-0.90), respectively. In conclusion, we found that isoflavone intake was associated with a decreased risk of localized prostate cancer.     

Phytoestrogens and thyroid cancer risk: the San Francisco Bay Area thyroid cancer study.

Epidemiological and pathological data suggest that thyroid cancer may well be an estrogen-dependent disease. The relationship between thyroid cancer risk and dietary phytoestrogens, which can have both estrogenic and antiestrogenic properties, has not been previously studied. We present data from a multiethnic population-based case-control study of thyroid cancer conducted in the San Francisco Bay Area. Of 817 cases diagnosed between 1995 and 1998 (1992 and 1998 for Asian women), 608 (74%) were interviewed. Of 793 controls identified through random-digit dialing, 558 (70%) were interviewed. Phytoestrogen consumption was assessed via a food-frequency questionnaire and a newly developed nutrient database. The consumption of traditional and nontraditional soy-based foods and alfalfa sprouts were associated with reduced risk of thyroid cancer. Consumption of "western" foods with added soy flour or soy protein did not affect risk. Of the seven specific phytoestrogenic compounds examined, the isoflavones, daidzein and genistein [odds ratio (OR), 0.70; 95% confidence interval (CI), 0.44-1.1; and OR, 0.65, 95% CI, 0.41-1.0, for the highest versus lowest quintile of daidzein and genistein, respectively] and the lignan, secoisolariciresinol (OR, 0.56; 95% CI, 0.35-0.89, for the highest versus lowest quintile) were most strongly associated with risk reduction. Findings were similar for white and Asian women and for pre- and postmenopausal women. Our findings suggest that thyroid cancer prevention via dietary modification of soy and/or phytoestrogen intake in other forms may be possible but warrants further research at this time.     

Plasma isoflavone levels versus self-reported soy isoflavone levels in Asian-American women in Los Angeles County

In a case-control study conducted among Asian-American women in Los Angeles County, we reported that the risk of breast cancer was significantly reduced in association with soy intake [Wu,A.H., Wan,P., Hankin,J. et al. (2002) Carcinogenesis, 23, 1491-1496]. In a subset of cases (n = 97) and controls (n = 97) we investigated the relationship between self-reported usual adult intake of soy isoflavones which was determined from a food frequency questionnaire and levels of plasma isoflavones (genistein and daidzein) and isoflavone metabolites (equol, dihydrogenistein and dihydrodaidzein) from a randomly timed blood specimen. In analyses conducted in cases and controls separately, levels of plasma genistein, daidzein and total isoflavones increased with increasing levels of self-reported intake of soy isoflavones. Breast cancer cases and control subjects did not differ in their respective associations between total plasma isoflavone levels and self-reported intake (P = 0.48). Among all subjects, there was a 3-fold difference in geometric mean plasma levels of total isoflavones [81.8 (95% CI = 53.4, 125.1) versus 26.4 nmol/l (95% CI = 16.6, 41.8)] between women in the highest quartile of soy isoflavone intake (>12.68 mg isoflavones/1000 kcal) compared with those in the lowest quartile of intake (相似文献   

Lack of prospective associations between plasma and urinary phytoestrogens and risk of prostate or colorectal cancer in the European Prospective into Cancer-Norfolk study

Dietary phytoestrogens are suggested to reduce the risk of prostate and colorectal cancer, but the results of epidemiologic studies have not yielded consistent support for this proposed effect, possibly due to inadequate databases of phytoestrogen levels in foods. Biomarkers of phytoestrogen intakes may provide a clearer insight into the relationship between phytoestrogen exposure and the risk of prostate or colorectal cancer risks. From the European Prospective into Cancer-Norfolk cohort (ages 45-75), serum and urine samples were analyzed for seven phytoestrogens [daidzein, enterodiol, enterolactone, genistein, glycitein, O-desmethylangolensin (O-DMA), and equol] among 193 cases of prostate cancer and 828 controls, and 221 cases of colorectal cancer with 889 controls. Summary variables of total lignans (enterodiol and enterolactone) and total isoflavones (daidzein, genistein, O-DMA, equol, and glycitein) were created and analyzed in conjunction with individual phytoestrogens. Logistic regression analyses revealed that there was no significant association between prostate cancer risk and total serum isoflavones [odds ratio (OR), 1.01; 95% confidence interval (CI), 0.93-1.10] or total serum lignans (OR, 0.94; 95% CI, 0.86-1.04) or between colorectal cancer risk and total serum isoflavones (OR, 1.01; 95% CI, 0.94-1.08) or total serum lignans (OR, 1.03; 95% CI, 0.94-1.12). Similarly, null associations were observed for individual serum phytoestrogens and for all urinary phytoestrogen biomarkers. In conclusion, we have found no evidence to support an inverse association between phytoestrogen exposure and prostate or colorectal cancer risk.     

Dietary phytoestrogen intake and premenopausal breast cancer risk in a German case-control study

A diet high in isoflavonoids (soy) is associated with lower breast cancer risk in Asian populations. Due to the low soy intake, dietary lignans may be the more important phytoestrogen class in Western populations. We used a population-based case-control study of breast cancer by age 50 in southern Germany to evaluate the association between dietary intake of different phytoestrogens and premenopausal breast cancer risk. Dietary information was collected from 278 premenopausal cases and 666 age-matched controls, using a validated FFQ. Using multivariate logistic regression, the highest vs. lowest intake quartiles of daidzein and genistein yielded significantly reduced ORs (95% CI) for breast cancer risk of 0.62 (0.40-0.95) and 0.47 (0.29-0.74), respectively. The protective effects of daidzein and genistein were found only for hormone receptor-positive tumors. High intake of other isoflavonoids, e.g., formononetin and biochanin A, as well as the sum of isoflavonoids were not associated with a decrease in risk. Breast cancer risk significantly decreased with a high intake of the plant lignan matairesinol (OR = 0.58, 95% CI 0.37-0.94) but not secoisolariciresinol or the sum of plant lignans. However, both estimated mammalian lignans, enterodiol and enterolactone, were inversely associated with breast cancer risk, with ORs (95% CI) of 0.61 (0.39-0.98) and 0.57 (0.35-0.92), respectively. No effect was found for total phytoestrogen intake. Our results suggest an important role of dietary intake of daidzein and genistein, despite low levels, as well as of matairesinol and mammalian lignans to reduce premenopausal breast cancer risk in this study population.     

Healthy Plant Foods Intake Could Protect Against Prostate Cancer Risk: A Case-Control Study

Background: Several studies have investigated the association between healthy plant foods intake and prostate cancer risk with inconsistent results. So this study was conducted to examine the existence of any possible association between healthy plant foods and prostate cancer risk. Materials and Methods: Sixty newly diagnosed prostate cancer cases and 60 controls engaged in a hospital-based case-control study. A validated 16o-items semi-quantitative FFQ was used to assess usual dietary intakes. Energy-adjusted amounts of healthy plant foods intake were calculated using the residual method. Logistic regression model was also used to derive beta estimates and odds ratios. Results: Cases were older and more likely to be inactive. In crude model, individuals in the highest tertile vs lowest tertile of total healthy plant foods (OR= 0.12; 95 % CI 0.04, 0.34), total fruits (OR= 0.11; 95 % CI 0.04, 0.30), total vegetables (OR= 0.08; 95 % CI 0.03, 0.24), fresh fruits (OR= 0.11; 95 % CI 0.04, 0.30), and raw vegetables (OR= 0.06; 95 % CI 0.02, 0.18) had significantly lower risk of prostate cancer. After controlling for potential confounders (age, BMI, total energy intake, job, education, smoking, physical activity, some drug usage, and also dietary intakes), just total healthy plant foods (OR= 0.12; 95 % CI 0.02, 0.55), total vegetables (OR=0.03; 95 % CI 0.00, 0.25), and raw vegetables (OR= 0.01; 95 % CI 0.00, 0.12) were associated with lower prostate cancer risk. Conclusions: The results of this study suggest that a diet rich in healthy plant foods and especially total or raw vegetable may protect against prostate cancer.     

Prospective cohort study on the relationship between dietary intake of soy food and total cancer mortality risk in urban Shanghai北大核心CSCD

Objective: To investigate the relationship between soy food intake and total cancer mortality risk. Methods: In the Shanghai Men's Health Study (2002-2013) and the Shanghai Women's Health Study (1997-2013), the food frequency questionnaires were used to collect information concerning soy food intake. Hazard ratio (HR) and 95% confidence interval (CI) for the association of soy food intake and total cancer mortality risk were derived using the COX proportional hazards model with adjustment of potential confounders. Results: During average 9.2 years for men and 14.7 years for women of follow-up, 2 122 cancer deaths were identified from 59 857 male participants, while 2 580 cancer deaths were identified from 73 044 female participants. Compared with the lowest quartile of soy food consumption, the HR s of the highest quartile intake group were 0.99 (95% CI: 0.87-1.12) and 0.96 (95% CI: 0.85-1.08) for the risk of total cancer mortality in men and women, respectively. It suggested that the association of soy food intake with total cancer mortality risk was not statistically significant. The further analyses showed the relationship between dietary soy isoflavones intake and total cancer mortality risk was not statistically significant in both men and women, the corresponding HR s were 1.06 (95% CI: 0.93-1.19) and 0.98 (95% CI: 0.88-1.10). Conclusion: Dietary intake of soy food may be not associated with the decreased risk of total cancer mortality. Copyright © 2017 by TUMOR All rights reserved.     

Do preserved foods increase prostate cancer risk?

Preserved foods have been found in some studies to be associated with increased cancer risks. The possible relationship between preserved foods and prostate cancer was investigated in a case-control study in southeast China during 2001-2002 covering 130 histologically confirmed cases and 274 inpatient controls without malignant disease. The total amount of preserved food consumed was positively associated with cancer risk, the adjusted odds ratio being 7.05 (95% CI: 3.12-15.90) for the highest relative to the lowest quartile of intake. In particular, the consumption of pickled vegetables, fermented soy products, salted fish and preserved meats was associated with a significant increase in prostate cancer risk, all with a significant dose-response relationship.     

Phytoestrogen consumption and endometrial cancer risk: a population-based case–control study in New Jersey

Phytoestrogens have been shown to exert anti-estrogenic and estrogenic effects in some tissues, including the breast. However, only a few studies have evaluated their role in endometrial cancer risk. We evaluated this association in a population-based case–control study in New Jersey. A total of 424 cases and 398 controls completed an interview, including a food frequency questionnaire with supplemental questions for phytoestrogen foods. Risk estimates were derived using an unconditional logistic regression, adjusting for major risk factors for endometrial cancer. There was some suggestion of a decreased risk with quercetin intake (OR: 0.65; 95% CI: 0.41–1.01 for the highest compared to the lowest quartile; p for trend: 0.02). We found a limited evidence of an association with any of the lignans evaluated, total lignans, coumestrol, individual isoflavones, total isoflavones, or total phytoestrogens. However, there was some suggestion of an inverse association with total isoflavone intake limited to lean women (BMI <25; OR for the highest tertile: 0.50; 95% CI: 0.25–0.98) and those with a waist-to-hip ratio ≤0.85 (OR: 0.59; 95% CI: 0.33–1.05). There was no evidence of effect modification by HRT use. This study suggests a reduction in endometrial cancer risk with quercetin intake and with isoflavone intake in lean women.     

Soybean products and reduction of breast cancer risk: a case-control study in Japan

Components of the Japanese diet, which might contribute to the relatively low breast cancer incidence rates in Japan, have not been clarified in detail. Since soybean products are widely consumed in Japan, a case-control study taking account of the menopausal status was conducted using data from the hospital-based epidemiologic research program at Aichi Cancer Center (HERPACC). In total, 167 breast cancer cases were included and 854 women confirmed as free of cancer were recruited as the control group. Odds ratios (OR) and 95% confidence intervals (95% CI) were determined by multiple logistic regression analysis. There were reductions in risk of breast cancer associated with high intake of soybean products among premenopausal women. Compared with women in the lowest tertile, the adjusted ORs for top tertile intake of tofu (soybean curd) was 0.49 (95% CI, 0.25-0.95). A significant decrease in premenopausal breast cancer risk was also observed for increasing consumption of isoflavones (OR=0.44; 95% CI, 0.22-0.89 for highest vs lowest tertile; P for trend=0.02). The present study found a statistically inverse association between tofu or isoflavone intake and risk of breast cancer in Japanese premenopausal women, while no statistically significant association was evident with the risk among postmenopausal women.     

Does high soy milk intake reduce prostate cancer incidence? The Adventist Health Study (United States)

Objectives: Recent experimental studies have suggested that isoflavones (such as genistein and daidzein) found in some soy products may reduce the risk of cancer. The purpose of this study was to evaluate the relationship between soy milk, a beverage containing isoflavones, and prostate cancer incidence.Methods: A prospective study with 225 incident cases of prostate cancer in 12,395 California Seventh-Day Adventist men who in 1976 stated how often they drank soy milk.Results: Frequent consumption (more than once a day) of soy milk was associated with 70 per cent reduction of the risk of prostate cancer (relative risk=0.3, 95 percent confidence interval 0.1-1.0, p-value for linear trend=0.03). The association was upheld when extensive adjustments were performed.Conclusions: Our study suggests that men with high consumption of soy milk are at reduced risk of prostate cancer. Possible associations between soy bean products, isoflavones and prostate cancer risk should be further investigated.     

Preserved foods in relation to risk of nasopharyngeal carcinoma in Shanghai, China

A population-based case-control study was conducted in Shanghai, China, to investigate the association between dietary factors and risk of nasopharyngeal carcinoma (NPC). The study included 935 NPC patients aged 15 to 74 years and 1,032 community controls. Exposures to salted fish and other protein-containing preserved food were associated with increased risk of NPC. Individuals who ate salted fish at least once a week had an 80% increase in risk of NPC relative to those who ate salted fish less than once a month (p = 0.07). Compared with those in the lowest quartile of protein-containing preserved foods, subjects in the highest quartile of intake experienced a statistically significant 78% increase in risk of NPC [odds ratio (OR) = 1.78, 95% confidence interval (CI) = 1.37-2.31], with a dose-dependent relationship (p for linear trend < 0.001 ). A similar association between intake of preserved vegetables and NPC risk was observed (OR = 1.39, p for linear trend = 0.003). In contrast, high intake of oranges/tangerines was associated with a statistically significant reduction in risk of NPC (OR = 0.55, p for linear trend < 0.001). When we examined the joint effect of preserved food and oranges/tangerines on risk of NPC, subjects in the highest tertile of preserved food and the lowest tertile of orange/ tangerine intake had a 3-fold increase in risk (95% CI = 2.08-4.91) compared with those in the lowest tertile of preserved food and the highest tertile of orange/tangerine intake.     

Breast Cancer and Dietary Factors in Taiwanese Women

Objectives To examine the effect of the consumption of dietary factors on the risk of breast cancer in a case–control study in Taiwan.Methods Two-hundred-and-fifty cases and 219 age-matched controls between the ages of 25 and 74 were interviewed in person between 1996 and 1999. Usual consumption of dietary habits including 100 foods was assessed using a food frequency questionnaire and a nutrient database developed and validated in Taiwanese populations.Results Cases consumed significantly more fat than controls. Cases also consumed statistically significant less supplements such as vitamins and mineral than controls. Food group analyses showed that highest quartile of beef and pork intake significantly increased risk in younger women (OR = 2.5, 95% CI = 1.0–6.0) and all women (OR = 2.5, 95% CI = 1.1–3.3). The age- education- and total calorie-adjusted odds ratio (OR) of breast cancer risk comparing the highest and second highest quartile of fat intake to the lowest quartile was 5.1, 95% confidence interval (CI): 2.1–13 and 3.5, 95% CI: 1.4–8.7 among those younger cases (≤40). A multiple regression model indicates a protective effect of supplements (OR: 0.40, 95% CI: 0.3–07) and a harmful effect of dietary fat (OR: 2.6, 95% CI: 1.4–5.0) for the highest versus lowest quartile in all women.Conclusions Our results indicate a strong protective effect of dietary supplements and a harmful effect of dietary fats on the risk of breast cancer among women in Taiwan. These findings should be confirmed in future follow-up studies. Specific amount of dietary supplements and dietary fats should be quantified for a more accurate evaluation on the risk for breast cancer in this population.^★ Supported by the Koo Foundation Cancer Center Research Fund.     

Epidemiology of soy exposures and breast cancer risk

Most of the early studies published on soy and breast cancer were not designed to test the effect of soy; the assessment of soy intake was usually crude and few potential confounders were considered in the analysis. In this review, we focused on studies with relatively complete assessment of dietary soy exposure in the targeted populations and appropriate consideration for potential confounders in the statistical analysis of study data. Meta-analysis of the 8 (1 cohort, 7 case-control) studies conducted in high-soy-consuming Asians show a significant trend of decreasing risk with increasing soy food intake. Compared to the lowest level of soy food intake (or=20 mg isoflavones per day). In contrast, soy intake was unrelated to breast cancer risk in studies conducted in the 11 low-soy-consuming Western populations whose average highest and lowest soy isoflavone intake levels were around 0.8 and 0.15 mg per day, respectively. Thus, the evidence to date, based largely on case-control studies, suggest that soy food intake in the amount consumed in Asian populations may have protective effects against breast cancer.     

Dietary acrylamide and risk of renal cell cancer

The detection of acrylamide, classified as a probable human carcinogen, in commonly consumed foods created public health alarm. Thus far, only 2 epidemiologic studies have examined the effect of dietary acrylamide on cancer risk. Presently, we reanalyzed data from a large population-based Swedish case-control study of renal cell cancer. Food frequency data were linked with national food databases on acrylamide content, and daily acrylamide intake was estimated for participants. The risk of renal cell cancer was evaluated for intake of food items with elevated acrylamide levels and for total daily acrylamide dose. Adjusting for potential confounders, there was no evidence that food items with elevated acrylamide, including coffee (OR(highest vs. lowest quartile) = 0.7; 95% CI = 0.4-1.1), crisp breads (OR(highest vs. lowest quartile) = 1.0; 95% CI = 0.6-1.6) and fried potatoes (OR(highest vs. lowest quartile) = 1.1; 95% CI = 0.7-1.7), were associated with a higher risk of renal cell cancer risk. Furthermore, there was no association between estimated daily acrylamide intake through diet and cancer risk (OR(highest vs. lowest quartile) = 1.1; 95% CI = 0.7-1.8; p for trend = 0.8). The results of this study are in line with the 2 previous studies examining dietary acrylamide and suggest there is no association between dietary acrylamide and risk of renal cell cancer.     

Legume and isoflavone intake and prostate cancer risk: The Multiethnic Cohort Study

Findings from studies of legume, soy and isoflavone intake and prostate cancer risk are as yet inconclusive, although soy has received considerable attention due to its high phytoestrogen content. Therefore, the present study investigated the relationship of these dietary exposures to prostate cancer risk in the Multiethnic Cohort Study in Hawaii and Los Angeles. The analyses included 82,483 men who completed a detailed quantitative food frequency questionnaire in 1993-1996. A total of 4,404 prostate cancer cases including 1,278 nonlocalized or high-grade cases were recorded during the average follow-up period of 8 years. Multivariate relative risks (RR) and 95% of confidence intervals (CI) were estimated using Cox proportional hazards models with age as the time metric. Among men with the highest intake of legumes, the risk reduction was 11% for total prostate cancer (RR = 0.89, 95% CI = 0.80-0.99, p for trend = 0.007) and 26% for nonlocalized or high-grade cancer (RR = 0.74, 95% CI = 0.61-0.90, p for trend = 0.007) compared to men with the lowest intake. Similar risk reductions were observed for soy products and for legumes excluding soy products in separate analyses. We found no significant risk reduction associated with intake of total or specific isoflavones for either total prostate cancer or for nonlocalized or high-grade cancer. The findings of our study suggest that legume intake is associated with a moderate reduction in prostate cancer risk and that the isoflavones in soy products are probably not responsible for this effect.     

Meat Consumption,Related Nutrients,Obesity and Risk of Prostate Cancer: a Case-Control Study in Uruguay

Background: In order to determine the role of meat consumption and related nutrients in the etiology of prostate cancer we conducted a case-control study among Uruguayan men in the time period 1998-2007. Results: The study included 464 cases and 472 controls, frequency matched for age and residence. Both series were drawn from the four major public hospitals in Montevideo. Unconditional logistic regression was used to estimate odds ratios (ORs) and 95 % confidence intervals (95 % CI) of prostate cancer by quartiles of meat intake and related nutrients. The highest vs. the lowest quartile of intake of total meat (OR = 5.19, 95 % CI 3.46-7.81), red meat (OR = 4.64, 95 % CI 3.10-6.95), and processed meat (OR = 1.78, 95% CI 1.22-2.59) were associated with increased risk of prostate cancer. Meat nutrients were directly associated with the risk of prostate cancer (OR for cholesterol 5.61, 95 % CI 3.75-8.50). Moreover, both total meat and red meat displayed higher risks among obese patients. Conclusions: This study suggests that total and red meat and meat nutrients may play a role in the etiology of prostate cancer in Uruguay.     

Adolescent diet and breast cancer in Utah

A population-based case-control study was conducted to assess the association between breast cancer risk, body mass index (BMI) and adolescent dietary fat and fiber consumption. Data were collected in Utah from white female cases (N = 172) and controls (N = 190) between the ages of 20 and 54 years. Odds ratios (OR) and 95% test-based confidence intervals (CI) were determined by multiple-logistic regression analysis controlling for age, education, age at menarche, and age at first pregnancy. Menopausal status was identified as an effect modifier, therefore, separate analyses were performed for pre and postmenopausal groups. An elevated risk (OR = 2.9 for highest quartile versus lowest, CI = 1.1-8.1) was associated with a larger BMI at age 12 in premenopausal women; a larger adult BMI lowered the odds ratio (OR = 0.4, CI = 0.2-1.0 for highest quartile versus lowest) in premenopausal women; BMI did not alter risk in postmenopausal women. Although not statistically significant, high fat intake consistently lowered the odds ratios below 1.0 in premenopausal women in the upper three quartiles compared to the lowest fat intake referent quartile (OR = 0.7, CI = 0.2-2.1 for highest versus lowest quartile) but was inconsistent in postmenopausal women (OR = 0.7, CI = 0.2-2.7 for highest versus lowest quartile). When fat intake was assessed by its component parts, fat from milk, cheese and yogurt reduced the odds ratios in both premenopausal (OR = 0.4, CI = 0.1-1.1 for highest versus lowest quartile) and postmenopausal women (OR = 0.2, CI = 0.0-0.8). In postmenopausal women, high fiber intake produced elevated odds ratios in all three upper quartiles (OR = 6.6, CI = 1.5-29.6 for highest versus lowest quartile), while fiber from grains resulted in a decreased risk in both premenopausal (OR = 0.2, 95% CI = 0.2-0.7 for highest versus lowest quartile) and postmenopausal women (OR = 0.7, 95% CI = 0.3-2.0). The possibility of biased estimates from low response rates (cases = 60%, controls = 61%), potential recall bias, and some lack of precision in the dietary instrument should be considered. It appears from these analyses that the relation of breast cancer to dietary intake, especially during adolescent years, is not clear, and that risk associated with fat or fiber intake may be affected by the nutrient source.     

A case--control study of selenium in nails and prostate cancer risk in British men

In view of the experimental evidence suggesting that the micronutrient selenium reduces prostate cancer risk, we investigated the association between the selenium level in fingernails, a measure of long-term selenium intake, and prostate cancer risk in a case-control study among 656 British men, conducted in 1989-1992. Nail clippings were taken at the time of recruitment and selenium concentration, measured using neutron activation techniques, was successfully assayed for 300 case-control pairs and varied six-fold among the controls (0.59 p.p.m.; interquartile range, 0.50-0.71 p.p.m.). Nail selenium concentration was not significantly associated with prostate cancer risk: men in the highest quartile of nail selenium had a slightly increased risk compared with men in the lowest quartile (OR 1.24, 95 CI, 0.73-2.10); for advanced prostate cancer, men in the highest quartile had a slightly reduced risk compared with men in the lowest quartile (OR 0.78, 95% CI, 0.27-2.25). These results suggest that selenium is not strongly associated with prostate cancer risk in British men.     

Dietary intake of isoflavones and coumestrol and the risk of prostate cancer in the Prostate,Lung, Colorectal and Ovarian Cancer Screening Trial

Experimental studies have revealed that phytoestrogens may modulate the risk of certain sites of cancer due to their structural similarity to 17β‐estradiol. The present study investigates whether intake of these compounds may influence prostate cancer risk in human populations. During a median follow up of 11.5 years, 2,598 cases of prostate cancer (including 287 advanced cases) have been identified among 27,004 men in the intervention arm of the Prostate, Lung, Colorectal and Ovarian Cancer Screening Trial. Dietary intake of phytoestrogens (excluding lignans) was assessed with a food frequency questionnaire. Cox proportional hazards regression analysis was performed to estimate hazard ratios (HRs) and 95% confidence intervals (CI) for dietary isoflavones and coumestrol in relation to prostate cancer risk. After adjustment for confounders, an increased risk of advanced prostate cancer [HR (95% CI) for quintile (Q) 5 vs. Q1] was found for the dietary intake of total isoflavones [1.91 (1.25–2.92)], genistein [1.51 (1.02–2.22), daidzein [1.80 (1.18–2.75) and glycitein [1.67 (1.15–2.43)] (p‐trend for all associations ≤0.05). For example, HR (95% CI) for comparing the Q2, Q3, Q4 and Q5 with Q1 of daidzein intake was 1.45 (0.93–2.25), 1.65 (1.07–2.54), 1.73 (1.13–2.66) and 1.80 (1.18–2.75), respectively (p‐trend: 0.013). No statistically significant associations were observed between the intake of total isoflavones and individual phytoestrogens and non‐advanced and total prostate cancer after adjustment for confounders. This study revealed that dietary intake of isoflavones was associated with an elevated risk of advanced prostate cancer.