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[Efficacy of lycopene intake in primary prevention of prostate cancer: a systematic review of the literature and meta-analysis.].
Cataño, JG, Trujillo, CG, Caicedo, JI, Bravo-Balado, A, Robledo, D, Mariño-Alvarez, AM, Pedraza, A, Arcila, MJ, Plata, M
Archivos espanoles de urologia. 2018;(2):187-197
Abstract
OBJECTIVE To evaluate the efficacy of lycopene intake in primary prevention of prostate cancer (PCa). METHODS A systematic search of the literature was conducted in March 2015 and the articles published between the years 1990-2015 were reviewed. The following search terms were used: prostate cancer, prostatic neoplasm, lycopene, prevention, effectiveness and efficacy (MeSH). Publications including research in humans, written in English and whose texts were accessible were reviewed. The types of studies included were: clinical trials, cohort and case-control studies. We found 343 articles; of these, 27 were included in the systematic review. After the latter were rigorously analyzed, 23 were included in the meta-analysis using the pooled odds ratios (OR) and risk ratios (RR) of case-control and cohort studies, respectively, and their confidence intervals (95% CI), using random-effects models with Review Manager 5.2. RESULTS Out of the 27 articles included in the systematic review, 22 were case-control and 5 were cohort studies. For the case-control studies, the total number of patients with PCa was 13,999 and the total number of controls 22,028. Cohort studies included 187,417 patients and PCa was diagnosed in 8,619 of these. The metaanalysis determined an OR = 0.94 (IC 95% 0.89-1.00) and RR = 0.9 (IC 95% 0.85-0.95) of PCa related with lycopene and/or raw or cooked tomatoes intake. CONCLUSIONS Although our study found that there is a statistically significant inverse association between lycopene intake and PCa, the magnitude of this association is weak and comes solely from observational studies, which do not allow recommending its use as a standard of practice. High-quality randomized clinical trials are required to clarify current evidence.
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Soy Consumption and the Risk of Prostate Cancer: An Updated Systematic Review and Meta-Analysis.
Applegate, CC, Rowles, JL, Ranard, KM, Jeon, S, Erdman, JW
Nutrients. 2018;(1)
Abstract
Prostate cancer (PCa) is the second most commonly diagnosed cancer in men, accounting for 15% of all cancers in men worldwide. Asian populations consume soy foods as part of a regular diet, which may contribute to the lower PCa incidence observed in these countries. This meta-analysis provides a comprehensive updated analysis that builds on previously published meta-analyses, demonstrating that soy foods and their isoflavones (genistein and daidzein) are associated with a lower risk of prostate carcinogenesis. Thirty articles were included for analysis of the potential impacts of soy food intake, isoflavone intake, and circulating isoflavone levels, on both primary and advanced PCa. Total soy food (p < 0.001), genistein (p = 0.008), daidzein (p = 0.018), and unfermented soy food (p < 0.001) intakes were significantly associated with a reduced risk of PCa. Fermented soy food intake, total isoflavone intake, and circulating isoflavones were not associated with PCa risk. Neither soy food intake nor circulating isoflavones were associated with advanced PCa risk, although very few studies currently exist to examine potential associations. Combined, this evidence from observational studies shows a statistically significant association between soy consumption and decreased PCa risk. Further studies are required to support soy consumption as a prophylactic dietary approach to reduce PCa carcinogenesis.
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The association between green tea consumption and breast cancer risk: A systematic review and meta-analysis.
Najaf Najafi, M, Salehi, M, Ghazanfarpour, M, Hoseini, ZS, Khadem-Rezaiyan, M
Phytotherapy research : PTR. 2018;(10):1855-1864
Abstract
This systematic review and meta-analysis aimed to critically evaluate the relation between green tea (GT) consumption and the risk of breast cancer. Popular electronic databases were systematically searched for papers in English language. All case-control and cohort studies in addition to randomized clinical trials were included if they assessed the chemopreventive effects of GT on breast cancer. The quality of included studies was assessed using the Newcastle-Ottawa and Jadad scale. This systematic review comprised 14 studies: 9 case-control studies, 4 cohort studies, and 1 clinical trial. Odds ratio (OR) in case-control studies suggested that women in the group receiving the highest level of GT had 19% reduction in breast cancer risk compared with those who received the lowest level of GT (summary OR = 0.81, p = .031; 95% CI [0.66, 0.981]; heterogeneity, I2 = 71.53, p < .001, random effect model; 9 studies). OR in cohort studies also showed no significant difference (OR = 0.99, p = .94; 95% CI [0.81, 1.138]; heterogeneity, I2 = 19.06, p = .29; fixed-effect model; 4 studies). According to the only clinical trial, treatment with GT could not alter the mammographic density compared with placebo (26% vs. 25%). It cannot be concluded that GT consumption may decrease the risk of breast cancer. Due to high heterogeneity, a pooled analysis of case-control and cohort studies was not performed.
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Non-herbal tea consumption and ovarian cancer risk: a systematic review and meta-analysis of observational epidemiologic studies with indirect comparison and dose-response analysis.
Zhang, D, Kaushiva, A, Xi, Y, Wang, T, Li, N
Carcinogenesis. 2018;(6):808-818
Abstract
Ovarian cancer (OC) accounts for 4% of female malignancies worldwide, and its prognosis is unfavorable. Currently available epidemiologic data suggest that non-herbal tea consumption may reduce OC risk, but these evidences are inconsistent. A comprehensive literature search for observational epidemiologic studies reporting associations between non-herbal tea consumption and OC risk was conducted in electronic databases. A random-effects model was used to synthesize effect measures in binary meta-analysis, and adjusted indirect comparison was used to compare whether there was a difference in effects between green tea (GT) and black tea (BT). Both linear and non-linear models were used to explore the dose-response relationship. Fourteen studies were included, and we obtained an inverse and significant pooled estimate in binary meta-analysis [risk ratio (RR)pool = 0.76, 95% confidence interval (CI) 0.61-0.95, PCochran < 0.001, I2 = 81.5%]. No publication bias was identified in binary meta-analysis. In binary meta-analysis stratified by tea types, we observed a significant association for GT (RRpool = 0.64, 95% CI 0.45-0.90, PCochran = 0.071, I2 = 53.6%), but not BT (RRpool = 0.85, 95% CI 0.65-1.12, PCochran = 0.007, I2 = 65.9%). Indirect comparison, which treated BT as the reference, showed an inverse but non-significant association (RRGT versus BT = 0.74, 95% CI 0.48-1.15). Both linear and non-linear models found that OC risk decreased as the consumption levels of total non-herbal tea increased. However, the dose-response relationship was stronger for GT when compared with BT. Our results suggest that non-herbal tea, especially GT, is associated with a reduced risk of OC. Future studies should explore biochemical evidence regarding the variation in chemopreventive effects between different types of non-herbal tea.