Fruit, vegetables, fibre and micronutrients and risk of US renal cell carcinoma

Unveiling the Effects of Cruciferous Vegetable Intake on Different Cancers: A Systematic Review and Dose-Response Meta-analysis

CONTEXT

Epidemiological studies indicated that cruciferous vegetable intake is associated with positive health outcomes. However, the role of cruciferous vegetables may have differential impacts on various cancers.

OBJECTIVE

This meta-analysis aims to review recent epidemiological studies on the link between cruciferous vegetables and various cancers. It seeks to identify the optimal intake dose and timing of cruciferous vegetables influencing their association with cancer risk.

DATA SOURCES

Studies on cruciferous vegetables and cancer were searched in PubMed, NCBI, Web of Science, and Elsevier databases from 1978 to June 2023.

DATA EXTRACTION

Extracted data from 226 relevant case-control and cohort studies were expressed by standardized mean difference and 95% CI, followed by the subgroup analysis to eliminate heterogeneity.

RESULTS

Intake of cruciferous vegetables can prevent cancers, with an odds ratio of 0.77 and risk ratio (RR) of 0.96. The intake levels of cruciferous vegetables associated with the risk of colorectal cancer, lung cancer, upper gastrointestinal cancer, gynecological cancer (ovarian cancer and endometrial cancer), bladder cancer, renal cancer, and prostate cancer were found to be 5.41 servings/week, 5.41 servings/week, 5.5 servings/week, 7.4 servings/week, 5.5 servings/week, 4.85 servings/week, and 3 servings/week, respectively. In a cohort followed for 2 to 15 years, limited consumption of cruciferous vegetables was correlated with a higher cancer RR. In the Asian population, cruciferous vegetables had a significant relationship with lung cancer, head and neck squamous cell carcinoma, and esophageal cancer. Conversely, cruciferous vegetables are predominantly associated with colorectal, renal, gynecological, and prostate cancer in the American population.

CONCLUSION

This study highlights the complex link between cruciferous vegetables and cancer, influenced by factors such as cancer type, region, intake level, and follow-up duration.

Effect of smoking, hypertension and lifestyle factors on kidney cancer - perspectives for prevention and screening programmes

Renal cell carcinoma (RCC) incidence has doubled over the past few decades. However, death rates have remained stable as the number of incidental renal mass diagnoses peaked. RCC has been recognized as a European health care issue, but to date, no screening programmes have been introduced. Well-known modifiable risk factors for RCC are smoking, obesity and hypertension. A direct association between cigarette consumption and increased RCC incidence and RCC-related death has been reported, but the underlying mechanistic pathways for this association are still unclear. Obesity is associated with an increased risk of RCC, but interestingly, improved survival outcomes have been reported in obese patients, a phenomenon known as the obesity paradox. Data on the association between other modifiable risk factors such as diet, dyslipidaemia and physical activity with RCC incidence are conflicting, and potential mechanisms underlying these associations remain to be elucidated.

Phytochemicals for the Prevention and Treatment of Renal Cell Carcinoma: Preclinical and Clinical Evidence and Molecular Mechanisms

Renal cell carcinoma (RCC) is associated with about 90% of renal malignancies, and its incidence is increasing globally. Plant-derived compounds have gained significant attention in the scientific community for their preventative and therapeutic effects on cancer. To evaluate the anticancer potential of phytocompounds for RCC, we compiled a comprehensive and systematic review of the available literature. Our work was conducted following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses criteria. The literature search was performed using scholarly databases such as PubMed, Scopus, and ScienceDirect and keywords such as renal cell carcinoma, phytochemicals, cancer, tumor, proliferation, apoptosis, prevention, treatment, in vitro, in vivo, and clinical studies. Based on in vitro results, various phytochemicals, such as phenolics, terpenoids, alkaloids, and sulfur-containing compounds, suppressed cell viability, proliferation and growth, showed cytotoxic activity, inhibited invasion and migration, and enhanced the efficacy of chemotherapeutic drugs in RCC. In various animal tumor models, phytochemicals suppressed renal tumor growth, reduced tumor size, and hindered angiogenesis and metastasis. The relevant antineoplastic mechanisms involved upregulation of caspases, reduction in cyclin activity, induction of cell cycle arrest and apoptosis via modulation of a plethora of cell signaling pathways. Clinical studies demonstrated a reduced risk for the development of kidney cancer and enhancement of the efficacy of chemotherapeutic drugs. Both preclinical and clinical studies displayed significant promise of utilizing phytochemicals for the prevention and treatment of RCC. Further research, confirming the mechanisms and regulatory pathways, along with randomized controlled trials, are needed to establish the use of phytochemicals in clinical practice.

Can Diet Prevent Urological Cancers? An Update on Carotenoids as Chemopreventive Agents

Urological cancers, namely prostate, bladder, kidney, testicular, and penile cancers, are common conditions that constitute almost one-quarter of all malignant diseases in men. Urological cancers tend to affect older individuals, and their development is influenced by modifiable metabolic, behavioral, and environmental risk factors. Phytochemicals may have cancer-fighting properties and protect against cancer development, slow its spread, and reduce the risk of cancer deaths in humans. This paper aims to review the current literature in regard to the effects of carotenoids in reducing urological cancer risk.

Novel molecules as the emerging trends in cancer treatment: an update

As per World Health Organization cancer remains as a leading killer disease causing nearly 10 million deaths in 2020. Since the burden of cancer increases worldwide, warranting an urgent search for anti-cancer compounds from natural sources. Secondary metabolites from plants, marine organisms exhibit a novel chemical and structural diversity holding a great promise as therapeutics in cancer treatment. These natural metabolites target only the cancer cells and the normal healthy cells are left unharmed. In the emerging trends of cancer treatment, the natural bioactive compounds have long become a part of cancer chemotherapy. In this review, we have tried to compile about eight bioactive compounds from plant origin viz. combretastatin, ginsenoside, lycopene, quercetin, resveratrol, silymarin, sulforaphane and withaferin A, four marine-derived compounds viz. bryostatins, dolastatins, eribulin, plitidepsin and three microorganisms viz. Clostridium, Mycobacterium bovis and Streptococcus pyogenes with their well-established anticancer potential, mechanism of action and clinical establishments are presented.

Anti-Inflammatory and Anticancer Effects of Microalgal Carotenoids

Acute inflammation is a key component of the immune system's response to pathogens, toxic agents, or tissue injury, involving the stimulation of defense mechanisms aimed to removing pathogenic factors and restoring tissue homeostasis. However, uncontrolled acute inflammatory response may lead to chronic inflammation, which is involved in the development of many diseases, including cancer. Nowadays, the need to find new potential therapeutic compounds has raised the worldwide scientific interest to study the marine environment. Specifically, microalgae are considered rich sources of bioactive molecules, such as carotenoids, which are natural isoprenoid pigments with important beneficial effects for health due to their biological activities. Carotenoids are essential nutrients for mammals, but they are unable to synthesize them; instead, a dietary intake of these compounds is required. Carotenoids are classified as carotenes (hydrocarbon carotenoids), such as α- and β-carotene, and xanthophylls (oxygenate derivatives) including zeaxanthin, astaxanthin, fucoxanthin, lutein, α- and β-cryptoxanthin, and canthaxanthin. This review summarizes the present up-to-date knowledge of the anti-inflammatory and anticancer activities of microalgal carotenoids both in vitro and in vivo, as well as the latest status of human studies for their potential use in prevention and treatment of inflammatory diseases and cancer.

Components of one-carbon metabolism and renal cell carcinoma: a systematic review and meta-analysis

PURPOSE

Little is known about the aetiology of renal cell carcinoma (RCC). Components of one-carbon (1C) metabolism, which are required for nucleotide synthesis and methylation reactions, may be related to risk of RCC but existing evidence is inconclusive. We conducted a systematic review and independent exposure-specific meta-analyses of dietary intake and circulating biomarkers of 1C metabolites and RCC risk.

METHODS

Medline and Embase databases were searched for observational studies investigating RCC or kidney cancer incidence or mortality in relation to components of 1C metabolism and 12 eligible articles were included in the meta-analyses. We used Bayesian meta-analyses to estimate summary relative risks (RRs) and 95% credible intervals (CrIs) comparing the highest versus lowest categories as well as the between-study heterogeneity.

RESULTS

We did not find convincing evidence of an association between any exposure (riboflavin, vitamin B6, folate, vitamin B12, methionine, homocysteine, choline, or betaine) and RCC risk. However, vitamin B6 biomarker status did have a protective (RR = 0.62) but imprecise (95% CrI 0.39-1.14) effect estimate and folate intake had a notable association as well (RR = 0.85, 95% CrI 0.71-1.01).

CONCLUSION

There was a lack of precision due largely to the low number of studies. Further investigation is warranted, especially for folate and vitamin B6, which had consistent suggestive evidence of a protective effect for both dietary intake and biomarker status. A unique strength of this review is the use of Bayesian meta-analyses which allowed for robust estimation of between-study heterogeneity.

Dietary fiber, glycemic index, glycemic load and renal cell carcinoma risk

Several epidemiological studies have investigated the potential association between dietary fiber, glycemic index (GI) or glycemic load (GL), and renal cell carcinoma (RCC) risk with inconsistent results. The aim of this study was to systematically evaluate this issue with a meta-analysis approach. A comprehensive literature search up to March 2018 was performed in PubMed and Web of Science databases. Summary relative risks (RRs) and 95% confidence intervals (CIs) were estimated with a random-effects model. Twelve studies were finally included in this study (eight for fiber analysis, five for GI and five for GL). A significant positive association was observed between GI and the risk of RCC (summary RR 1.16, 95% CI 1.02-1.32), and no significant heterogeneity was detected among studies (I2 = 22.8%, P = 0.262). A significant inverse association was found between fiber intake and the risk of RCC (summary RR 0.82, 95% CI 0.72-0.92), and no significant heterogeneity was observed across studies (I2 = 27.6%, P = 0.218). GL was not significantly associated with RCC risk (summary RR 1.14, 95% CI 0.81-1.60), and significant heterogeneity was found across studies (I2 = 78.6%, P < 0.001). In conclusion, this systematic review and meta-analysis suggests that dietary GI and fiber may be associated with the risk of RCC. Further large prospective cohort studies are still warranted to confirm our preliminary findings.

Lycopene Triggers Nrf2-AMPK Cross Talk to Alleviate Atrazine-Induced Nephrotoxicity in Mice

Atrazine (ATR), an environmental persistent and bioaccumulative herbicide, has been associated with environmental nephrosis. Lycopene (LYC) exhibits important properties of nephroprotection, but there are limited data on the specific underlying mechanism. The primary objective of this study was to explore the therapeutic effect of LYC on ATR-induced nephrotoxicity in mice. The mice were divided randomly into 6 groups and treated as follows: control group (C), 5 mg/kg LYC group (L), 50 mg/kg ATR group (A1), 200 mg/kg ATR group (A2), 50 mg/kg ATR plus 5 mg/kg LYC group (A1+L), and 200 mg/kg ATR plus 5 mg/kg LYC group (A2+L) by oral gavage administration for 21 days. We found that pretreatment with LYC significantly suppressed the ATR-induced renal tubular epithelial cell swelling. Furthermore, LYC mitigated ATR-induced dysregulation of oxidative stress markers by reducing MDA, H₂O₂ levels, and increasing SOD, GPx, CAT concentration, and Nrf2 activation. Moreover, LYC activated the autophagic flux by a detectable change in autophagy-related genes (Beclin-1 and ATGs) and proteins (p62/SQSTM) and by the formation of autophagic vacuole (AV) and LC3 aggregation, in parallel with AMPK activation (pAMPK/AMPK). Herein, ATR-up-regulated nuclear factor erythroid 2-related factor 2 (Nrf2) expression and Nrf2-regulated redox genes, including quinoneoxidoreductase-1 (NQO1) and heme oxidase-1 (HO1), whereas LYC down-regulated those of the above genes. In addition, LYC suppressed ATR-induced activation of autophagy (increased LC3II/LC3I, ATGs, Beclin1, and p62, in parallel with increased AMPK activation). Collectively, our findings identified a cross talk between AMPK-activated autophagy and the Nrf2 signaling pathway in LYC-mediated nephroprotection against ATR-induced toxicity in mice kidney.

Renal cell carcinoma risk associated with lower intake of micronutrients

Kidney cancer incidence in African Americans (AA) is higher than among European Americans (EA); reasons for this disparity are not fully known. Dietary micronutrients may have a protective effect on renal cell carcinoma (RCC) development by inhibiting oxidative DNA damage and tumor growth. We evaluated whether any micronutrient associations differed by race in the US Kidney Cancer Study. 1142 EA and AA RCC cases and 1154 frequency‐matched controls were enrolled in a population‐based case‐control study between 2002 and 2007. Dietary micronutrient intake was derived from an interviewer‐administered diet history questionnaire. RCC risk associated with micronutrient intake was estimated using adjusted odds ratios from logistic regression comparing lower to highest quartiles of intake and sample weighting. Inverse associations with RCC risk were observed for α‐carotene, β‐carotene, lutein zeaxanthin, lycopene, vitamin A, folate, thiamin, vitamin C, α‐tocopherol, β‐tocopherol, γ‐tocopherol, and selenium. A trend for β‐cryptoxanthin was suggested among EA but not AA or the total sample (P‐interaction = .04). Otherwise, findings did not differ by race, gender, age, or smoking status. The increase in RCC risk associated with lower micronutrient intake is similar within AA and EA populations. A diet rich in sources of micronutrients found in fruits, vegetables, and nuts may help to reduce the overall risk of RCC.

Consumption of fruits and vegetables and risk of renal cell carcinoma: a meta-analysis of observational studies

Background

There have been inconsistent results about the association between consumption of fruits and vegetables and renal cell carcinoma (RCC) risk. We conducted a meta-analysis of the published observational studies to explore this association.

Results

Nineteen observational studies (4 cohort, 1 pooled and 14 case-control studies), involving 10,215 subjects with RCC were part of this meta-analysis. The SRR for the highest vs. the lowest intake of vegetables was 0.73 (95% CI: 0.63–0.85; P_{heterogeneity} = 0.004, I² = 53.5%), whereas for fruits it was 0.86 (95% CI: 0.75–0.98; P_{heterogeneity} = 0.012, I² = 47.4%). Linear dose-response analysis also showed similar results, e.g., for per 1 serving/day increment of vegetables, the SRR was 0.90 (95% CI: 0.84–0.96) and for fruits it was 0.97 (95% CI: 0.93–1.01). Nonlinear association was only observed for vegetables (P_nonlinearity = 0.001), but not for fruits (P_nonlinearity = 0.221).

Materials and Methods

Eligible studies up to August 31, 2016 were identified and retrieved by searching MEDLINE and EMBASE databases along with manual review of the reference list from the retrieved studies. Quality of included studies was evaluated using Newcastle-Ottawa Quality Assessment Scale (NOS). Random-effects model was used to calculate summary relative risk (SRR) and corresponding 95% confidence interval (CI).

Conclusions

This meta-analysis indicated a protective effect of consumption of vegetables and fruits on RCC risk. Further studies are warranted with prospective designs that use validated questionnaires and control for important confounders.

Hormone factors play a favorable role in female head and neck cancer risk

Due to lower female incidence, estimates of exogenous and endogenous hormonal factors in head and neck cancers (HNCs, comprising cancers of the oral cavity, oropharynx, hypopharynx, and larynx) among women have been inconsistent and unable to account for key HNC risk factors. We pooled data from 11 studies from Europe, North America, and Japan. Analysis included 1572 HNC female cases and 4343 controls. Pooled odds ratios (ORs) estimates and their 95% confidence intervals (CIs) were calculated using multivariate logistic regression models adjusting for tobacco smoking and alcohol drinking. Lower risk was observed in women who used hormone replacement therapy (HRT) (OR = 0.58; 95% CI: 0.34–0.77). Pregnancy (OR = 0.61; 95% CI: 0.42–0.90) and giving birth (OR = 0.59; 95% CI: 0.38–0.90) at <35 years of age were inversely associated with HNCs. An inverse association with HNC was observed with age at start of HRT use (OR = 0.59; 95% CI: 0.39–0.90) for each additional 10 years and with duration of use (OR = 0.87; 95% CI: 0.76–0.99 for every 3 years). Exogenous female hormone use is associated with a nearly twofold risk reduction in female HNCs. The lower female HNC incidence may, in part, be explained by endogenous and exogenous estrogen exposures.

Alcohol and Dietary Folate Intake and Promoter CpG Island Methylation in Clear-Cell Renal Cell Cancer

We investigated whether alcohol and dietary folate intakes were associated with promoter methylation in clear-cell renal cell carcinoma (ccRCC). The Netherlands Cohort Study with a case-cohort design included 120,852 subjects aged 55-69 yr in 1986. Diet was measured with a food-frequency questionnaire. After 20.3 yr of follow-up, paraffin-embedded tumor blocks were collected. Methylation-specific polymerase chain reaction (MSP) was used to analyze promoter methylation of 11 genes. ccRCC cases were classified into low (0-19% of the genes), intermediate (20-39%), and high (40%+) methylation. Multivariable Cox regression analyses were conducted, stratified according to methylation, including 3980 subcohort members and 297 ccRCC cases. Increasing alcohol intake was associated with decreased ccRCC risk, but was not statistically significant; multivariable adjusted hazard ratio (HR) for ≥30 g alcohol/day versus 0 g/day was 0.78 [95% confidence interval (CI): 0.48-1.24], and P-value for trend was 0.46. In strata according to methylation index, no significant heterogeneity was observed. Dietary folate intake was not associated with ccRCC risk. There was no significant heterogeneity between strata according to methylation index. There was no effect modification of alcohol and dietary folate intake on ccRCC risk, nor in strata according to methylation index. Our findings do not support the hypothesis that alcohol and dietary folate intakes are involved in ccRCC.

Renal cell carcinoma: links and risks

This review provides an overview of the incidence of renal cell carcinoma (RCC) and a summary of the most commonly associated risk factors. A literature review was performed with a focus on recent studies with a high level of evidence (large prospective cohort studies and meta-analyses). The incidence rate of RCC varies globally, with the rate rising rapidly in more developed regions, demonstrating the effects of increased use of diagnostic imaging and prevalence of modifiable risk factors. Based on the current evidence, cigarette smoking, obesity, and hypertension are the most well-established risk factors for sporadic RCC worldwide. Acquired cystic kidney disease is also a significant risk factor, specifically in dialysis patients. There is increasing evidence for an inverse association between RCC risk and moderate alcohol consumption. Certain analgesics and occupational exposure have been linked to an increased risk of RCC, although data are limited. Diets rich in fruits and vegetables may provide a protective effect.

Vitamin C intake and risk of renal cell carcinoma: a meta-analysis

Studies have showed that vitamin C intake is linked to renal cell carcinoma risk, however, the results were inconsistent. Hence, the present meta-analysis was to examine the association between vitamin C intake and RCC risk. We searched the published studies that reported the relationship between vitamin C intake and RCC risk using PubMed and Embase up to January 2015. Based on a fixed effects model, RR and the corresponding 95% CI were used to assess the pooled risk. 3 prospective cohort studies and 7 case-control studies were included. The overall RR (95% CI) of RCC for the highest vs. the lowest levels of vitamin C intake was 0.78(0.69,0.87). Little evidence of heterogeneity was found. In the subgroup analyses, we found an inverse association between vitamin C intake and RCC risk in the case-control studies but not in the prospective cohort studies. Additionally, this association between vitamin C intake and RCC risk was not differed by population distribution. Our study provides evidence that vitamin C intake is associated with a reduced RCC risk. However, our conclusion was just based on ten including studies, so more high-quality of case-control studies or cohort studies which report this topic are needed.

One-Carbon Metabolic Factors and Risk of Renal Cell Cancer: A Meta-Analysis

BACKGROUND

Nutrients related to one-carbon metabolism were previously shown to be significantly associated with the risk of cancer. The aim of this meta-analysis was to evaluate potential relationships between one-carbon metabolic factors and renal cell cancer (RCC) risk.

METHODS

PubMed, EMBASE, and Cochrane Library databases were searched through March 2015 for observational studies of quantitative RCC risk estimates in relation to one-carbon metabolic factors. The relative risks (RRs) with 95% confidence intervals (CIs) measured the relationship between one-carbon metabolic factors and RCC risk using a random-effects model.

RESULTS

Of the 463 citations and abstracts identified by database search, seven cohorts from five observational studies reported data on 133,995 individuals, and included 2,441 RCC cases. Comparing the highest with the lowest category, the pooled RRs of RCC were 0.72 (95%CI: 0.52-1.00; P = 0.048) for vitamin B12. In addition, an increase in folic acid supplementation of 100 μg/day was associated with a 3% lower risk of RCC (RR, 0.97; 95%CI: 0.93-1.00; P = 0.048). Similarly, an increase of 5 nmol/L of vitamin B2 was associated with a reduced risk of RCC 0.94 (95%CI: 0.89-1.00; P = 0.045). Sensitivity analyses suggested that a higher serum vitamin B6 might contribute to a reduced risk of RCC (RR, 0.83; 95%CI: 0.77-0.89; P < 0.001).

CONCLUSIONS

Higher levels of serum vitamin B2, B6, B12, and folic acid supplementation lowered the risk of RCC among the study participants.

Impacts of a farmers' market incentive programme on fruit and vegetable access, purchase and consumption

OBJECTIVE

The present study examines the impact of Health Bucks, a farmers' market incentive programme, on awareness of and access to farmers' markets, and fruit and vegetable purchase and consumption in low-income New York City neighbourhoods.

DESIGN

The evaluation used two primary data collection methods: (i) an on-site point-of-purchase survey of farmers' market shoppers; and (ii) a random-digit-dial telephone survey of residents in neighbourhoods where the programme operates. Additionally, we conducted a quasi-experimental analysis examining differential time trends in consumption before and after programme introduction using secondary Community Health Survey (CHS) data.

SETTING

New York City farmers' markets and communities.

SUBJECTS

Farmers' market shoppers (n 2287) completing point-of-purchase surveys in a representative sample of New York City farmers' markets in 2010; residents (n 1025) completing random-digit-dial telephone survey interviews in 2010; and respondents (n 35 606) completing CHS interviews in 2002, 2004, 2008 and 2009.

RESULTS

Greater Health Bucks exposure was associated with: (i) greater awareness of farmers' markets; (ii) increased frequency and amount of farmers' market purchases; and (iii) greater likelihood of a self-reported year-over-year increase in fruit and vegetable consumption. However, our CHS analysis did not detect impacts on consumption.

CONCLUSIONS

While our study provides promising evidence that use of farmers' market incentives is associated with increased awareness and use of farmers' markets, additional research is needed to better understand impacts on fruit and vegetable consumption.

Antioxidant micronutrients and the risk of renal cell carcinoma in the Women's Health Initiative cohort

BACKGROUND

Renal cell carcinoma (RCC) is the eighth leading cancer among women in incidence and commonly is diagnosed at a more advanced stage. Oxidative stress has been considered to play an important role in the pathogenesis of RCC. Various dietary micronutrients have antioxidant properties, including carotenoids and vitamins C and E; thus, diets rich in these nutrients have been evaluated in relation to RCC prevention. The objective of this study was to explore the correlation between antioxidant micronutrients and the risk of RCC.

METHODS

In total, 96,196 postmenopausal women who enrolled in the Women's Health Initiative (WHI) between 1993 and 1998 and were followed through July 2013 were included in this analysis. Dietary micronutrient intake was estimated from the baseline WHI food frequency questionnaire, and data on supplement use were collected using an interview-based inventory procedure. RCC cases were ascertained from follow-up surveys and were centrally adjudicated. The risks for RCC associated with intake of α-carotene, β-carotene, β-cryptoxanthin, lutein plus zeaxanthin, lycopene, vitamin C, and vitamin E were analyzed using Cox proportional hazards regression adjusted for confounders.

RESULTS

Two hundred forty women with RCC were identified during follow-up. Lycopene intake was inversely associated with RCC risk (P = .015); compared with the lowest quartile of lycopene intake, the highest quartile of intake was associated with a 39% lower risk of RCC (hazard ratio, 0.61; 95% confidence interval, 0.39-0.97). No other micronutrient was significantly associated with RCC risk.

CONCLUSIONS

The current results suggest that further investigation into the correlation between lycopene intake and the risk of RCC is warranted.

Nutritional countermeasures targeting reactive oxygen species in cancer: from mechanisms to biomarkers and clinical evidence

Reactive oxygen species (ROS) exert various biological effects and contribute to signaling events during physiological and pathological processes. Enhanced levels of ROS are highly associated with different tumors, a Western lifestyle, and a nutritional regime. The supplementation of food with traditional antioxidants was shown to be protective against cancer in a number of studies both in vitro and in vivo. However, recent large-scale human trials in well-nourished populations did not confirm the beneficial role of antioxidants in cancer, whereas there is a well-established connection between longevity of several human populations and increased amount of antioxidants in their diets. Although our knowledge about ROS generators, ROS scavengers, and ROS signaling has improved, the knowledge about the direct link between nutrition, ROS levels, and cancer is limited. These limitations are partly due to lack of standardized reliable ROS measurement methods, easily usable biomarkers, knowledge of ROS action in cellular compartments, and individual genetic predispositions. The current review summarizes ROS formation due to nutrition with respect to macronutrients and antioxidant micronutrients in the context of cancer and discusses signaling mechanisms, used biomarkers, and its limitations along with large-scale human trials.

Cruciferous vegetables intake is associated with lower risk of renal cell carcinoma: evidence from a meta-analysis of observational studies

Background

Epidemiologic studies have evaluated the association between cruciferous vegetables(CV) intake and the risk of renal cell carcinoma(RCC); however, the existing results are controversial. The aim of this meta-analysis was to investigate the association between CV intake and RCC risk.

Methods

A literature search was carried out using PUBMED and EMBASE database between January 1966 and March 2013. Fixed-effect and random-effect models were used to estimate summary relative risks (RR) and the corresponding 95% confidence intervals (CIs). Potential sources of heterogeneity were detected by meta-regression. Subgroup analyses, sensitivity analysis and cumulative meta-analysis were also performed.

Results

A total of 12 studies (six cohorts, six case–control) contributed to the analysis, involving 1,228,518 participants and 5,773 RCC cases. When all studies were pooled, we observed a significantly inverse association between CV intake and RCC risk (RR = 0.81, 95% CI [0.72, 0.91]). This association was also significant when analyses were restricted to six high-quality studies (RR = 0.89, 95% CI [0.82, 0.98]). In subgroup analyses, CV intake was significantly associated with reduced RCC risk among studies conducted in America (RR = 0.77, 95%CI [0.70, 0.86]); however, CV intake had no significant association with RCC risk among studies conducted in Europe (RR = 0.87, 95%CI [0.71, 1.07]). Furthermore, sensitivity analysis confirmed the stability of results.

Conclusions

The findings of this meta-analysis suggested that high intake of CV was inversely associated with RCC risk among Americans. More studies, especially high quality cohort studies with larger sample size, well controlled confounding factors are warranted to confirm this association.

Hypertension in adolescence is not an independent risk factor for renal cancer: a cohort study of 918,965 males

BACKGROUND

Hypertension has been repeatedly linked to renal cell cancer, independent of overweight and anti-hypertensive drug use, but its role remains unclear, especially within the growing group of relatively young-middle aged renal cancer patients. In order to delineate the role of hypertension in early onset renal cancer, we examined the association of blood pressure measured at age 17 with the incidence of renal cancer.

METHODS

Sociodemographic and medical data of 918,965 adolescent males examined for fitness for military service from 1967 to 2005 were linked to the National Cancer Registry in this nationwide population-based cohort study (12,910,585 person years) to obtain cancer incidence. A single measurement of blood pressure at age 17 was stratified as optimal (<120/80), normal (≥ 120/80 < 130/85), high normal (≥ 130/85 < 140/90), or high (≥ 140/90). We used Cox proportional hazards modeling to estimate the hazard ratio of the blood pressure categories for renal cancer, adjusted for year of birth, body mass index, origin of parents, and height. We also assessed the role of a clinical diagnosis of persistent hypertension (n = 4223, based on multiple measurements).

RESULTS

Of those who had their blood pressure recorded, 90 examinees developed renal cancer. In a multivariable model, the higher categories of blood pressure were associated with a decreased risk of renal cancer (hazard ratio, 0.32; 95% confidence interval, 0.12-0.84; P = .021 for blood pressure ≥ 140/90 vs < 120/80). Furthermore, there was no evidence of increased risk for those with an established diagnosis of hypertension (hazard ratio, 1.28; 95% confidence interval, 0.17-9.50; P = .81).

CONCLUSIONS

It is unlikely that hypertension in adolescents carries an increased risk for renal cancer.

Intake of fiber and fiber-rich plant foods is associated with a lower risk of renal cell carcinoma in a large US cohort

BACKGROUND

Plant-based and fiber-rich diets high in vegetables, fruit, and whole grains are recommended to prevent cancer and chronic conditions associated with renal cell carcinoma (RCC), such as obesity, hypertension, and diabetes. Diet may play a role in the etiology of RCC directly and/or indirectly.

OBJECTIVE

In a large prospective cohort of US men and women, we comprehensively investigated dietary intake and food sources of fiber in relation to RCC risk.

DESIGN

Participants of the NIH-AARP Diet and Health Study (n = 491,841) completed a self-administered questionnaire of demographics, diet, lifestyle, and medical history. Over 9 (mean) years of follow-up we identified 1816 incident cases of RCC. HRs and 95% CIs were estimated within quintiles by using multivariable Cox proportional hazards regression.

RESULTS

Total dietary fiber intake was associated with a significant 15-20% lower risk of RCC in the 2 highest quintiles compared with the lowest (P-trend = 0.005). Intakes of legumes, whole grains, and cruciferous vegetables were also associated with a 16-18% reduced risk of RCC. Conversely, refined grain intake was positively associated with RCC risk in a comparison of quintile 5 with quintile 1 (HR: 1.19; 95% CI: 1.02, 1.39; P-trend = 0.04). The inverse association between fiber intake and RCC was consistent among participants who never smoked, had a body mass index [BMI (in kg/m(2))] <30, and did not report a history of diabetes or hypertension.

CONCLUSIONS

Intake of fiber and fiber-rich plant foods was associated with a significantly lower risk of RCC in this large US cohort. This trial was registered at clinicaltrials.gov as NCT00340015.

Nutrients related to one-carbon metabolism and risk of renal cell cancer

PURPOSE

Folate, vitamins B6 and B12, methionine, choline, and betaine are nutrients related to one-carbon metabolism and have been hypothesized to decrease cancer risk. Few studies have evaluated dietary intakes of these nutrients in relation to renal cell cancer (RCC).

METHODS

We conducted prospective follow-up studies of women in the Nurses' Health Study and men in the Health Professionals Follow-up Study. Diet was assessed repeatedly using a validated semi-quantitative food-frequency questionnaire in both studies.

RESULTS

During follow-up of 24 years among 77,208 women (918,891 person-years) and 22 years among 47,886 men (1,731,752 person-years), we accrued 436 cases of RCC (225 women and 211 men). Intakes of folate, vitamins B6 and B12, methionine, and betaine were not found to be related to RCC risk. Higher intake of free choline, but not other forms of choline, was associated with reduced RCC risk. The results were similar in men and women.

CONCLUSIONS

We found little evidence that higher intakes of nutrients related to one-carbon metabolism lower RCC risk. One-carbon metabolism may have little influence on renal carcinogenesis.