Consumption of different types of meat and the risk of renal cancer: meta-analysis of case-control studies

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.

Food groups and urologic cancers risk: a systematic review and meta-analysis of prospective studies

Background

To assess the association between 12 food groups intake and the risk of urologic cancers.

Methods

We scanned PubMed and Web of Science databases up to April 1st, 2023, and 73 publications met the inclusion criteria in the meta-analysis. We used a random effects model to estimate the summary risk ratios (RRs) and 95% confidence intervals (95% CI).

Results

In the linear dose-response meta-analysis, an inverse association was found between each additional daily 100 g of fruits [RR: 0.89, 95%CI = (0.83, 0.97)], 100 g of vegetables [RR: 0.92, 95%CI = (0.85, 0.99)], 12 g of alcohol [RR: 0.91, 95%CI = (0.88, 0.94)] and 1 cup of coffee [RR: 0.95, 95%CI = (0.83, 0.97)] intake and the risk of renal cell carcinoma. Conversely, each additional daily 100 g of red meat intake was positively associated with renal cell carcinoma [RR: 1.41, 95%CI = (1.03, 2.10)]. Inverse associations were observed between each additional daily 50 g of egg [RR: 0.73, 95%CI = (0.62, 0.87)] and each additional daily 1 cup of tea consumption and bladder cancer risk [RR: 0.97, 95%CI = (0.94, 0.99)]. There were no significant associations for nonlinear dose-response relationships between 12 food groups and urological cancers.

Conclusion

Our meta-analysis strengthens the evidence that appropriate intake of specific food groups, such as fruits, vegetables, alcohol, tea, and coffee, is associated with the risk of renal cell carcinoma or bladder cancer. More studies are required to fill the knowledge gap on the links between various food groups and urologic cancers because the evidence was less credible in this meta-analysis.

Systematic Review Registration

This study was registered on PROSPERO (CRD42022340336).

Poultry Consumption and Human Health: How Much Is Really Known? A Systematically Searched Scoping Review and Research Perspective

This scoping review was conducted to systematically search and chronicle scientific literature pertinent to poultry intake and human health. The protocol (uploaded to Open Science Framework, https://osf.io/2k7bj/) was conducted in accordance with Preferred Reporting Items for Systematic Reviews and Meta-Analyses extension for scoping reviews guidelines. Articles with observational and experimental research, narrative and systematic reviews, and meta-analyses were included. Among 13,141 articles identified, 525 met inclusion criteria. Among these 525 articles, 212 focused on cancer morbidity and mortality; 41 on cardiovascular disease (CVD) morbidity and mortality; 52 on CVD risk factors; 32 on type 2 diabetes mellitus (T2DM) morbidity and mortality; 33 on T2DM risk factors; and 42 on body weight and body composition. An "Other" category (181 articles) included nutrient status, psychological well-being/mental health, cognition, microbiome, chronic kidney disease, nonalcoholic fatty liver disease, skin disorders, and fertility, among others. Among the 525 included articles, 366 were observational, 64 were experimental, and 76 were reviews and meta-analyses. Eighty-three percent of articles focused on adults or older adults. A paucity of research exists to support poultry as health-promoting foods, with most research only indirectly assessing poultry intake compared with other foods of interest (e.g., red meats or plant-based protein foods). No randomized controlled trials and only 1% of OBS assessed the influence of processed poultry intake on human health. In the future, the relative health effects of consuming poultry will be compared with a widening array of traditional and new protein-rich food products, necessitating the need for research to assess poultry as foods of choice. Science and health professionals, the poultry industry, and the public will benefit from new observational and experimental research to address cutting-edge scientific, public policy, and consumer topics pertinent to poultry intake and human health.

Total, red and processed meat consumption and human health: an umbrella review of observational studies

Meat consumption has represented an important evolutionary step for humans. However, modern patterns of consumption, including excess intake, type of meat and cooking method have been the focus of attention as a potential cause of rise in non-communicable diseases. The aim of this study was to investigate the association between total, red and processed meat with health outcomes and to assess the level of evidence by performing a systematic search of meta-analyses of prospective cohort studies. Convincing evidence of the association between increased risk of (i) colorectal adenoma, lung cancer, CHD and stroke, (ii) colorectal adenoma, ovarian, prostate, renal and stomach cancers, CHD and stroke and (iii) colon and bladder cancer was found for excess intake of total, red and processed meat, respectively. Possible negative associations with other health outcomes have been reported. Excess meat consumption may be detrimental to health, with a major impact on cardiometabolic and cancer risk.

A Web-Based Prediction Model for Cancer-Specific Survival of Elderly Patients With Clear Cell Renal Cell Carcinoma: A Population-Based Study

Background

Clear cell renal cell carcinoma (ccRCC) is expected in the elderly and poor prognosis. We aim to explore prognostic factors of ccRCC in the elderly and construct a nomogram to predict cancer-specific survival (CSS) in elderly patients with ccRCC.

Methods

Clinicopathological information for all elderly patients with ccRCC from 2004 to 2018 was downloaded from the Surveillance, Epidemiology, and End Results (SEER) program. All patients were randomly assigned to a training cohort (70%) or a validation cohort (30%). Univariate and multivariate Cox regression models were used to identify the independent risk factors for CSS. A new nomogram was constructed to predict CSS at 1-, 3-, and 5 years in elderly patients with ccRCC based on independent risk factors. Subsequently, we used the consistency index (C-index), calibration curves, and the area under the receiver operating curve (AUC) and decision curve analysis (DCA) to test the prediction accuracy of the model.

Results

A total of 33,509 elderly patients with ccRCC were enrolled. Univariate and multivariate Cox regression analyses results showed that age, sex, race, marriage, tumor size, histological grade, tumor, nodes, and metastases (TNM) stage, and surgery were independent risk factors for CSS in elderly patients with ccRCC. We constructed a nomogram to predict CSS in elderly patients with ccRCC. The C-index of the training cohort and validation cohort was 0.81 (95% CI: 0.802-0.818) and 0.818 (95% CI: 0.806-0.830), respectively. The AUC of the training cohort and validation cohort also suggested that the prediction model had good accuracy. The calibration curve showed that the observed value of the prediction model was highly consistent with the predicted value. DCA showed good clinical application value of the nomogram.

Conclusion

In this study, we explored prognostic factors in elderly patients with ccRCC. We found that age, sex, marriage, TNM stage, surgery, and tumor size were independent risk factors for CSS. We constructed a new nomogram to predict CSS in elderly patients with ccRCC with good accuracy and reliability, providing clinical guidance for patients and physicians.

The role of diet in renal cell carcinoma incidence: an umbrella review of meta-analyses of observational studies

BACKGROUND

Evidence associating diet with the incidence of renal cell carcinoma (RCC) is inconclusive. We aimed to summarize evidence associating dietary factors with RCC incidence and assess the strength and validity of this evidence.

METHODS

We conducted an umbrella review of systematic reviews or meta-analyses (SRoMAs) that assessed the association between diet and RCC incidence. Through April 2021, PubMed, Web of Science, Embase, The Cochrane Library, Scopus, and WCRF were searched. Two independent reviewers selected studies, extracted data, and appraised the quality of SRoMAs. According to credibility assessment criteria, evidence can be divided into five categories: convincing (class I), highly suggestive (class II), suggestive (class III), weak (class IV), and nonsignificant (class V).

RESULTS

Twenty-nine meta-analyses were obtained after screening. After excluding 7 overlapping meta-analyses, 22 meta-analyses including 502 individual studies and 64 summary hazard ratios for RCC incidence were included: dietary patterns or dietary quality indices (n = 6), foods (n = 13), beverages (n = 4), alcohol (n = 7), macronutrients (n =15), and micronutrients (n =19). No meta-analyses had high methodological quality. Five meta-analyses exhibited small study effects; one meta-analysis showed evidence of excess significance bias. No dietary factors showed convincing or highly suggestive evidence of association with RCC in the overall analysis. Two protective factors had suggestive evidence (vegetables (0.74, 95% confidence interval 0.63 to 0.86) and vitamin C (0.77, 0.66 to 0.90)) in overall analysis. One protective factor had convincing evidence (moderate drinking (0.77, 0.70 to 0.84)) in Europe and North America and one protective factor had highly suggestive evidence (cruciferous vegetables (0.78, 0.70 to 0.86)) in North America.

CONCLUSIONS

Although many meta-analyses have assessed associations between dietary factors and RCC, no high-quality evidence exists (classes I and II) in the overall analysis. Increased intake of vegetables and vitamin C is negatively associated with RCC risk. Moderate drinking might be beneficial for Europeans and North Americans, and cruciferous vegetables might be beneficial to North Americans, but the results should be interpreted with caution. More researches are needed in the future.

TRIAL REGISTRATION

PROSPERO CRD42021246619.

Association of Processed Meats and Alcohol Consumption with Renal Cell Carcinoma: A Worldwide Population-Based Study

The link between diet and renal cell carcinoma (RCC) is still unclear. The purpose of this study was to evaluate the association of diet with RCC's incidence and mortality rates worldwide. We conducted an ecological study including 170 countries, whose data on age-standardized (AS) incidence and mortality rates of RCC, dietary factors, and potentially confounding factors such as obesity, insufficient physical activity, tobacco smoking, hypertension, diabetes, and human development index (HDI) were collected and available on May 2020 from the Global Cancer Observatory, the Global Dietary Database, the Global Health Observatory data repository, the Diabetes Atlas 9th edition and the Human Development Report 2019. Univariable and multivariable linear regression analyses were performed to determine the association of dietary factors with incidence and mortality rates of RCC adjusted for the effects of population age and potentially confounding factors. Intake of processed meats and consumption of alcohol were both positively associated with AS incidence rates of RCC (β = 0.11, P < 0.001 and β = 0.1, P = 0.044, respectively). We suggest that high consumption of processed meats and/or alcohol is a risk factor for RCC. However, they were not associated with mortality. Further research is needed at an individual level.Supplemental data for this article is available online at https://doi.org/10.1080/01635581.2020.1856388.

Dietary Habit and Other Risk Factors of Chronic Kidney Disease Among Patients Attending Dessie Referral Hospital, Northeast Ethiopia

Background

In low- and middle-income countries, the burden of chronic kidney disease (CKD) is rising due to poor access to early detection and management services. In Ethiopia, little is known about the context-specific risk factors and their magnitude, particularly the dietary habit of patients is not studied. Therefore, this study aimed to identify the dietary and other risk factors of CKD in Northeast Ethiopia.

Methods

We conducted a facility-based unmatched case–control study utilizing quantitative method of data collection. Data were collected on a total of 66 cases and 134 controls using structured questionnaire and anthropometric measurements. Dietary habit was assessed using the Diet History Questionnaire (DHQ). Medical history, patient chart review and physical examination were employed to collect other relevant information. To identify independent predictors of CKD, we conducted a multivariable logistic regression analysis.

Results

About 54.5% cases and 46.3% of controls were female, while 40.9% of cases and 38.8% of controls were within the age group of 36–55. All cases and 128 (95.5%) controls consumed meat in the last year. Forty-six (69.7%) cases and 74 (55.2%) controls use palm oil as the main cooking oil. History of hypertension (adjusted odds ratio (AOR)=2.39; 95%CI: 1.17–4.89), anemia (AOR=2.38; 95%CI: 1.04–5.42), palm oil use (AOR=2.10; 95%CI: 1.01–4.35) and family history of CKD (AOR=8.77; 95%CI: 3.73–20.63) were significantly associated with the risk of having CKD.

Conclusion

Meat consumption and use of palm oil are higher among patients with CKD than controls. History of hypertension, anemia, family history of CKD and palm oil consumption were found to be risk factors for CKD. Dietary counseling interventions and dietary modifications might help in CKD prevention. Furthermore, routine urinalysis and estimation of glomerular filtration rate (GFR) for all hospitalized patients with hypertension and anemia could help to detect CKD at an earlier stage for a better prognosis.

Obesity and cancer risk: Emerging biological mechanisms and perspectives

Continuously rising trends in obesity-related malignancies render this disease spectrum a public health priority. Worldwide, the burden of cancer attributable to obesity, expressed as population attributable fraction, is 11.9% in men and 13.1% in women. There is convincing evidence that excess body weight is associated with an increased risk for cancer of at least 13 anatomic sites, including endometrial, esophageal, renal and pancreatic adenocarcinomas; hepatocellular carcinoma; gastric cardia cancer; meningioma; multiple myeloma; colorectal, postmenopausal breast, ovarian, gallbladder and thyroid cancers. We first synopsize current epidemiologic evidence; the obesity paradox in cancer risk and mortality; the role of weight gain and weight loss in the modulation of cancer risk; reliable somatometric indicators for obesity and cancer research; and gender differences in obesity related cancers. We critically summarize emerging biological mechanisms linking obesity to cancer encompassing insulin resistance and abnormalities of the IGF-I system and signaling; sex hormones biosynthesis and pathway; subclinical chronic low-grade inflammation and oxidative stress; alterations in adipokine pathophysiology; factors deriving from ectopic fat deposition; microenvironment and cellular perturbations including vascular perturbations, epithelial-mesenchymal transition, endoplasmic reticulum stress and migrating adipose progenitor cells; disruption of circadian rhythms; dietary nutrients; factors with potential significance such as the altered intestinal microbiome; and mechanic factors in obesity and cancer. Future perspectives regarding prevention, diagnosis and therapeutics are discussed. The aim of this review is to investigate how the interplay of these main potential mechanisms and risk factors, exerts their effects on target tissues provoking them to acquire a cancerous phenotype.

Targeted and Untargeted Detection of DNA Adducts of Aromatic Amine Carcinogens in Human Bladder by Ultra-Performance Liquid Chromatography-High-Resolution Mass Spectrometry

Epidemiological studies have linked aromatic amines (AAs) from tobacco smoke and some occupational exposures with bladder cancer risk. Several epidemiological studies have also reported a plausible role for structurally related heterocyclic aromatic amines present in tobacco smoke or formed in cooked meats with bladder cancer risk. DNA adduct formation is an initial biochemical event in bladder carcinogenesis. We examined paired fresh-frozen (FR) and formalin-fixed paraffin-embedded (FFPE) nontumor bladder tissues from 41 bladder cancer patients for DNA adducts of 4-aminobiphenyl (4-ABP), a bladder carcinogen present in tobacco smoke, and 2-amino-9 H-pyrido[2,3- b]indole, 2-amino-1-methyl-6-phenylimidazo[4,5- b]pyridine and 2-amino-3,8-dimethylimidazo[4,5- f]quinoxaline, possible human carcinogens, which occur in tobacco smoke and cooked meats. These chemicals are present in urine of tobacco smokers or omnivores. Targeted DNA adduct measurements were done by ultra-performance liquid chromatography-electrospray ionization multistage hybrid Orbitrap MS. N-(2'-Deoxyguanosin-8-yl)-4-ABP ( N-(dG-C8)-4-ABP) was the sole adduct detected in FR and FFPE bladder tissues. Twelve subjects (29%) had N-(dG-C8)-4-ABP levels above the limit of quantification, ranging from 1.4 to 33.8 adducts per 109 nucleotides (nt). DNA adducts of other human AA bladder carcinogens, including 2-naphthylamine (2-NA), 2-methylaniline (2-MA), 2,6-dimethylaniline (2,6-DMA), and lipid peroxidation (LPO) adducts, were screened for in bladder tissue, by our untargeted data-independent adductomics method, termed wide-selected ion monitoring (wide-SIM)/MS2. Wide-SIM/MS2 successfully detected N-(dG-C8)-4-ABP, N-(2'-deoxyadenosin-8-yl)-4-ABP and the presumed hydrazo linked adduct, N-(2'-deoxyguanosin- N2-yl)-4-ABP, and several LPO adducts in bladder DNA. Wide-SIM/MS2 detected multiple DNA adducts of 2-NA, 2-MA, and, 2,6-DMA, when calf thymus DNA was modified with reactive intermediates of these carcinogens. However, these AA-adducts were below the limit of detection in unspiked human bladder DNA (<1 adduct per 108 nt). Wide-SIM/MS2 can screen for many types of DNA adducts formed with exogenous and endogenous electrophiles and will be employed to identify DNA adducts of other chemicals that may contribute to the etiology of bladder cancer.

Ingested Nitrate, Disinfection By-products, and Kidney Cancer Risk in Older Women

BACKGROUND

N-nitroso compounds formed endogenously after nitrate/nitrite ingestion are animal renal carcinogens. Previous epidemiologic studies of drinking water nitrate did not evaluate other potentially toxic water contaminants, including the suspected renal carcinogen chloroform.

METHODS

In a cohort of postmenopausal women in Iowa (1986-2010), we used historical measurements to estimate long-term average concentrations of nitrate-nitrogen (NO3-N) and disinfection by-products (DBP) in public water supplies. For NO3-N and the regulated DBP (total trihalomethanes [THM] and the sum of five haloacetic acids [HAA5]), we estimated the number of years of exposure above one-half the current maximum contaminant level (>½-MCL NO3-N; >5 mg/L). Dietary intakes were assessed via food frequency questionnaire. We estimated hazard ratios (HRs) and 95% confidence intervals (CIs) with Cox models, and evaluated interactions with factors influencing N-nitroso compound formation.

RESULTS

We identified 125 incident kidney cancers among 15,577 women reporting using water from public supplies >10 years. In multivariable models, risk was higher in the 95th percentile of average NO3-N (HRp95vsQ1 = 2.3; CI: 1.2, 4.3; Ptrend = 0.33) and for any years of exposure >½-MCL; adjustment for total THM did not materially change these associations. There were no independent relationships with total THM, individual THMs chloroform and bromodichloromethane, or with haloacetic acids. Dietary analyses yielded associations with high nitrite intake from processed meats but not nitrate or nitrite overall. We found no interactions.

CONCLUSIONS

Relatively high nitrate levels in public water supplies were associated with increased risk of renal cancer. Our results also suggest that nitrite from processed meat is a renal cancer risk factor.

HIV-Related Stress and Life Chaos Mediate the Association Between Poverty and Medication Adherence Among People Living with HIV/AIDS

HIV treatment depends on high-levels of antiretroviral therapy (ART) adherence, which is severely impeded by poverty. Men and women living with HIV infection (N = 92) completed computerized interviews of demographic and health characteristics, poverty markers, stressful life events, and life chaos, as well as unannounced pill counts to determine prospective medication adherence and medical record chart abstractions for HIV viral load. Poverty markers were associated with both stressors and chaos, and the direct effects of all three factors predicted ART non-adherence. The multiple mediation model showed that accounting for stressors and chaos resulted in a non-significant association between poverty markers and ART adherence. The indirect effect of poverty markers on adherence through life chaos was significant, whereas the indirect effect of poverty markers on adherence through stressors was not significant. Factors that render HIV-related stress and create chaos offer intervention targets that are more amenable to change than poverty itself.

Intake of red and processed meat and risk of renal cell carcinoma: a meta-analysis of observational studies

Background

Findings on the association between intake of red and processed meat with renal cell carcinoma (RCC) risk are mixed. We conducted a meta-analysis to investigate this association.

Materials and Methods

Eligible studies up to August 31, 2016, were identified and retrieved by searching the MEDLINE and Embase databases along with manual review of the reference lists from the retrieved studies. The quality of the included studies was evaluated using the Newcastle-Ottawa Quality Assessment Scale. The summary relative risk (SRR) and corresponding 95% confidence interval (CI) were calculated using a random-effects model.

Results

Twenty-three publications were included in this meta-analysis: four cohort studies, one pooled study, and 18 case-control studies. The SRR (95% CI) for the highest vs. lowest intake of red meat was 1.36 (1.16–1.58, Pheterogeneity < 0.001); that for processed meat was 1.13 (95% CI, 1.03–1.24, Pheterogeneity = 0.014). Linear dose-response analysis yielded similar results, i.e., the SRR for per 100 g/day increment of red meat and per 50 g/day increment of processed meat was 1.21 (95% CI, 1.08–1.36) and 1.16 (95% CI, 0.99–1.36), respectively. A non-linear association was observed only for red meat (Pnonlinearity = 0.002), and not for processed meat (Pnonlinearity = 0.231). Statistically significant positive associations were observed for intake of beef, salami/ham/bacon/sausage, and hamburger.

Conclusions

This meta-analysis indicates a significant positive association between red and processed meat intake and RCC risk.

Renal cell carcinoma

Renal cell carcinoma (RCC) denotes cancer originated from the renal epithelium and accounts for >90% of cancers in the kidney. The disease encompasses >10 histological and molecular subtypes, of which clear cell RCC (ccRCC) is most common and accounts for most cancer-related deaths. Although somatic VHL mutations have been described for some time, more-recent cancer genomic studies have identified mutations in epigenetic regulatory genes and demonstrated marked intra-tumour heterogeneity, which could have prognostic, predictive and therapeutic relevance. Localized RCC can be successfully managed with surgery, whereas metastatic RCC is refractory to conventional chemotherapy. However, over the past decade, marked advances in the treatment of metastatic RCC have been made, with targeted agents including sorafenib, sunitinib, bevacizumab, pazopanib and axitinib, which inhibit vascular endothelial growth factor (VEGF) and its receptor (VEGFR), and everolimus and temsirolimus, which inhibit mechanistic target of rapamycin complex 1 (mTORC1), being approved. Since 2015, agents with additional targets aside from VEGFR have been approved, such as cabozantinib and lenvatinib; immunotherapies, such as nivolumab, have also been added to the armamentarium for metastatic RCC. Here, we provide an overview of the biology of RCC, with a focus on ccRCC, as well as updates to complement the current clinical guidelines and an outline of potential future directions for RCC research and therapy.

Dietary fruit, vegetable, fat, and red and processed meat intakes and Barrett's esophagus risk: a systematic review and meta-analysis

The relationships between dietary fruit, vegetable, fat, and red and processed meat intakes and Barrett’s esophagus (BE) risk remain inconclusive. We conducted a systematic review and meta-analysis to summarize the available evidence on these issues. PubMed, EMBASE and the Cochrane Library were searched for studies published from inception through October 2015. A total of eight studies were included in this analysis. Fruit intake was not associated with BE risk (OR = 0.65, 95% CI = 0.37–1.13), but vegetable intake was strongly associated with BE risk (OR = 0.45, 95% CI = 0.29–0.71). Saturated fat, red meat and processed meat intakes were not associated with BE risk with OR = 1.25 (95% CI = 0.82–1.91), OR = 0.85 (95% CI = 0.61–1.17) and OR = 1.03 (95% CI = 0.73–1.46), respectively. Dietary vegetable not fruits intake may be associated with decreased BE risk. Fat and red and processed meat intakes may not contribute to an increased BE risk. Well-designed, large prospective studies with better established dose-response relationships are needed to further validate these issues.

Cooking methods and the formation of PhIP (2-Amino, 1-methyl, 6-phenylimidazo[4,5-b] pyridine) in the crust of the habitually consumed meat in Argentina

Content of carcinogenic molecules like, 2-Amino, 1-methyl, 6-phenylimidazo[4,5-b] pyridine in meals is one of the main mutagenic substances formed during meat cooking, and it can be used as a dietary exposure marker. Our objective was to estimate the amount of PhIP consumed from habitual Argentinean diet, rich in red meats, comparing different cooking procedures and meat type. Samples (n = 240) of lean and fatty beef, chicken, pork, and fish were cooked using different methods: griddle, grill, sauté pan, and oven. Samples were: Overcooked, or cooked with a microbiologically suitable or "healthy technique" (HT). The PhIP was determined by HPLC-MS. Meats cooked using HT formed little crust amounts and PhIP was below the detection levels. In overcooked meats, large amounts of crust were formed in lean meats, fatty beef, fatty chicken and baked pork. PhIP was measured in lean meats sauted or cooked on a griddle, a method reaching temperatures until 250 °C.It was estimated that Argentine people eats about 12,268.0 ng/day of PhIP being these values above those tolerated limits for total dietary heterocyclic amines in some developed countries. Hence, cooking small meat portions, at medium temperature, avoiding prolonged cooking and preferring baked lean meats could be recommended as a healthier habit.

Red and processed meat consumption and risk of glioma in adults: A systematic review and meta-analysis of observational studies

BACKGROUND

These findings from several observational studies, investigated the association between red meat consumption and gliomas, were inconsistent. We conducted a systematic review and meta-analysis of observational studies to summarize available date on the relation between meat intake and risk of glioma.

MATERIALS AND METHODS

A systematic literature search of relevant reports published until May 2014 of the PubMed/Medline, ISI Web of Knowledge, Excerpta Medica database, Ovid database, Google Scholar, and Scopus databases was conducted. From 723 articles yielded in the preliminary literature search, data from eighteen publications (14 case-control, three cohort, and one nested case-control study) on unprocessed red meat, processed meat, and/or total red meat consumption in relation to glioma in adults were included in the analysis. Quality assessment of studies was performed. Random effects model was used to conduct the meta-analysis.

RESULTS

We found a positive significant association between unprocessed red meat intake and risk of glioma (relative risk [RR] = 1.30; 95% confidence interval [CI]: 1.08-1.58) after excluding three studies with uncertain type of brain cancer. This analysis included only one cohort study which revealed no relation between unprocessed red meat intake and glioma (RR = 1.75; 95% CI: 0.35-8.77). Consumption of processed meats was not related to increased risk of glioma in population-based case-control studies (RR = 1.26; 95% CI: 1.05-1.51) and reduced risk in hospital-based case-controls (RR = 0.79; 95% CI: 0.65-0.97). No significant association was seen between processed red meat intake and risk of glioma in cohort studies (RR: 1.08; 95% CI: 0.84-1.37). Total red meat consumption was not associated with risk of adult glioma in case-control or cohort studies.

CONCLUSION

In this meta-analysis of 18 observational studies, we found a modest positive association between unprocessed red meat intake and risk of gliomas based almost entirely on case-control studies. Processed red meat was overall not associated with risk of gliomas in case-control or cohort studies.

Meat consumption and cancer risk: a critical review of published meta-analyses

Dietary habits play a substantial role for increasing or reducing cancer risk. We performed a critical review of scientific literature, to describe the findings of meta-analyses that explored the association between meat consumption and cancer risk. Overall, 42 eligible meta-analyses were included in this review, in which meat consumption was assumed from sheer statistics. Convincing association was found between larger intake of red meat and cancer, especially with colorectal, lung, esophageal and gastric malignancies. Increased consumption of processed meat was also found to be associated with colorectal, esophageal, gastric and bladder cancers. Enhanced intake of white meat or poultry was found to be negatively associated with some types of cancers. Larger beef consumption was significantly associated with cancer, whereas the risk was not increased consuming high amounts of pork. Our analysis suggest increased risk of cancer in subjects consuming large amounts of red and processed meat, but not in those with high intake of white meat or poultry.

Gene-environment interaction of genome-wide association study-identified susceptibility loci and meat-cooking mutagens in the etiology of renal cell carcinoma

BACKGROUND

Meat-cooking mutagens may be associated with renal cell carcinoma (RCC) risk. In the current study, the authors examined associations between meat-cooking mutagens, genetic susceptibility variants, and risk of RCC.

METHODS

The authors used 659 newly diagnosed RCC cases and 699 healthy controls to investigate the association between dietary intake of meat-cooking mutagens and RCC. They examined whether associations varied by risk factors for RCC and genetic susceptibility variants previously identified from genome-wide association studies. Odds ratios and 95% confidence intervals were estimated using tertiles of intake of dietary polycyclic aromatic hydrocarbons/heterocyclic amines.

RESULTS

Dietary intake of the mutagenic compounds 2-amino-3,8-dimethylimidazo-(4,5-f) quinoxaline (MeIQx) and 2-amino-1 methyl-6-phenylimidazo(4,5-b)pyridine (PhIP) were found to be significantly associated with an increased risk of RCC (odds ratios across tertiles: 1.00 [referent], 1.28 [95% confidence interval, 0.94-1.74], and 1.95 [95% confidence interval, 1.43-2.66] [P for trend <.001], respectively; and 1.00 [referent], 1.41 [95% confidence interval, 1.04-1.90], and 1.54 [95% confidence interval, 1.14-2.07] [P for trend =.02], respectively). The authors observed evidence of interactions between PhIP and RCC susceptibility variants in 2 genes: inositol 1,4,5-trisphosphate receptor, type 2 (ITPR2) (rs718314; multiplicative P for interaction = .03 and additive P for interaction =.002) and endothelial PAS domain-containing protein 1 (EPAS1) (rs7579899; additive P for interaction =.06).

CONCLUSIONS

The intake of meat may increase the risk of RCC through mechanisms related to the cooking compounds MeIQx and PhIP. These associations may be modified by genetic susceptibility to RCC. Further research is necessary to understand the biological mechanisms underlying these interactions.

The impact of nutrition in urogenital cancers

Prostate, bladder and kidney cancers remain the most common cancers of the urinary tract. Despite improved primary prevention, detection and treatment, the incidence of age-related cancers of the urinary tract is likely to rise as a result of global population ageing. An association of diet with prostate, bladder and kidney carcinogenesis is plausible since the majority of metabolites, including carcinogens, are excreted through the urinary tract. Moreover, large regional differences in incidence rates of urologic tumours exist throughout the world. These rates change when people relocate to different geographic areas, which is suggestive of a strong environmental influence. As a result of these observations, numerous studies have been conducted to assess the effects of diet and nutritional status in kidney, bladder and prostate carcinogenesis. Here, we review the literature assessing the effect of diet and nutritional status on urological cancer risk, which has attracted the most interest.

Lycopene in the prevention of renal cell cancer in the TSC2 mutant Eker rat model

Renal cell carcinoma (RCC) is the most frequent upper urinary tract cancer in humans and accounts for 80-85% of malignant renal tumors. Eker rat represents a unique animal model to study RCC since these rats develop spontaneous renal tumors and leiomyoma, which may be due to tuberous sclerosis 2 (TSC2) mutation resulting in the activation of the mammalian target of rapamycin (mTOR) pathway. This study examines the role of a lycopene-rich diet in the development of RCC in the TSC2 mutant Eker rat model. Ten-week old female Eker rats (n=90) were assigned in equal numbers to receive 0, 100 or 200mg/kg of lycopene as part of their daily diet. After 18 months the rats were sacrificed and the kidneys were removed. Immunohistochemical staining with antibodies against mTOR, phospho-S6 and EGFR were performed, as well as hematoxylin-eosin staining for histologic examination of the tumors. Tumors were counted and measured in individual kidneys. Presence of tumor decreased from 94% in control animals to 65% in the experimental group, but the difference was not statistically significant (P<0.12). However, mean numbers of renal carcinomas were statistically significantly decreased in the lycopene-treated rats (P<0.008) when compared to untreated controls. In the lycopene group, tumor numbers decreased (P<0.002) and the numbers tended to decrease linearly (P<0.003) as supplemental lycopene increased from 0 to 200. Control rats fed only basal diet had a greater length of tumors (23.98 mm) than rats fed lycopene supplement groups (12.90 mm and 11.07 mm) (P<0.05). Moreover tumor length decreased (P<0.02) and tumor length tended to decrease linearly (P<0.03) as supplemental lycopene increased from 0 to 200mg/kg. All tumors showed strong staining with antibodies against mTOR, phospho-S6 and EGFR. In conclusion, dietary supplementation with lycopene attenuates the development of renal cell cancers in the predisposed TSC2 mutant Eker rat model. These results suggest that lycopene may play a role in the prevention of RCC.

Trends in consumption of ultra-processed foods and obesity in Sweden between 1960 and 2010

Objective

To investigate how consumption of ultra-processed foods has changed in Sweden in relation to obesity.

Design

Nationwide ecological analysis of changes in processed foods along with corresponding changes in obesity. Trends in per capita food consumption during 1960–2010 were investigated using data from the Swedish Board of Agriculture. Food items were classified as group 1 (unprocessed/minimally processed), group 2 (processed culinary ingredients) or group 3 (3·1, processed food products; and 3·2, ultra-processed products). Obesity prevalence data were pooled from the peer-reviewed literature, Statistics Sweden and the WHO Global Health Observatory.

Setting

Nationwide analysis in Sweden, 1960–2010.

Subjects

Swedish nationals aged 18 years and older.

Results

During the study period consumption of group 1 foods (minimal processing) decreased by 2 %, while consumption of group 2 foods (processed ingredients) decreased by 34 %. Consumption of group 3·1 foods (processed food products) increased by 116 % and group 3·2 foods (ultra-processed products) increased by 142 %. Among ultra-processed products, there were particularly large increases in soda (315 %; 22 v. 92 litres/capita per annum) and snack foods such as crisps and candies (367 %; 7 v. 34 kg/capita per annum). In parallel to these changes in ultra-processed products, rates of adult obesity increased from 5 % in 1980 to over 11 % in 2010.

Conclusions

The consumption of ultra-processed products (i.e. foods with low nutritional value but high energy density) has increased dramatically in Sweden since 1960, which mirrors the increased prevalence of obesity. Future research should clarify the potential causal role of ultra-processed products in weight gain and obesity.

Meat and fish consumption and the risk of renal cell carcinoma in the European prospective investigation into cancer and nutrition

Renal cell cancer (RCC) incidence varies worldwide with a higher incidence in developed countries and lifestyle is likely to contribute to the development of this disease. We examined whether meat and fish consumption were related to the risk of RCC in the European Prospective Investigation into Cancer and Nutrition (EPIC). The analysis included 493,179 EPIC participants, recruited between 1992 and 2000. Until December 2008, 691 RCC cases have been identified. Meat and fish consumption was assessed at baseline using country-specific dietary assessment instruments; 24-hour recalls were applied in an 8% subsample for calibration purposes. Cox proportional hazards regression was used to calculate multivariable-adjusted hazard ratios (HR) and 95% confidence intervals (CI). Women with a high consumption of red meat (HR = 1.36, 95% CI 1.14-1.62; calibrated, per 50 g/day) and processed meat (HR = 1.78, 95% CI 1.05-3.03; calibrated, per 50 g/day) had a higher risk of RCC, while no association existed in men. For processed meat, the association with RCC incidence was prominent in premenopausal women and was lacking in postmenopausal women (p interaction = 0.02). Neither poultry nor fish consumption were statistically significantly associated with the risk of RCC. The results show a distinct association of red and processed meat consumption with incident RCC in women but not in men. A biological explanation for these findings remains unclear.

Time for change? Food choices in the transition to cohabitation and parenthood

OBJECTIVE

We compared the dietary behaviour of three different household types and explored developmental trends in food choices following a life event.

DESIGN

The study is based on data from three Swiss Food Panel survey periods. A cross-sectional comparison between household types was conducted by using a one-way independent ANOVA. Repeated measures were analysed with a mixed ANCOVA to examine changes in dietary behaviour following a life event.

SETTING

Participants in the survey filled in a questionnaire in the years 2010, 2011 and 2012.

SUBJECTS

The final sample consisted of 3559 persons with a mean age of 56 years (range 22-94 years; 46 % men). Seventy-two people moved in with their partner and sixty-five people reported the birth of their first child.

RESULTS

Cross-sectional evidence confirmed that women living in households with a partner reported higher consumption frequencies for meat and processed meats compared with those living alone. Men living in cohabitation had a higher vegetable intake. The transitional effect of moving in with a partner, however, resulted in a higher intake of processed meats for both genders and a higher intake of pork and savoury items for men. Transition to motherhood was linked to an increase in vegetable consumption, while the transition to fatherhood did not change consumption patterns significantly.

CONCLUSIONS

Individuals in life-stage transitions are more likely to change their nutritional strategies and life events can be a window of opportunity for changes towards better food choices.

Meat consumption and risk of oral cavity and oropharynx cancer: a meta-analysis of observational studies

PURPOSE

High meat consumption, especially red and processed meat consumption is associated with an increased risk of several cancers, however, evidence for oral cavity and oropharynx cancer is limited. Thus, we performed this meta-analysis to determine the association between intakes of total meat, processed meat, red meat, and white meat, and the risk of oral cavity and oropharynx cancer.

METHODS

Electronic search of Pubmed, Embase, and Cochrane Library Central database was conducted to select relevant studies. 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 and sensitivity analysis were also performed.

RESULTS

12 case-control studies and one cohort study were included in the analyses, including 501,730 subjects and 4,104 oral cavity and oropharynx cancer cases. Pooled results indicated that high consumption of total meat, red meat, and white meat were not significantly associated with increased risk of oral cavity and oropharynx cancer (RR = 1.14, 95% CI[0.78-1.68]; RR = 1.05, 95% CI[0.66, 1.66] and RR = 0.81, 95% CI[0.54, 1.22], respectively), while the high consumption of processed meat was significantly associated with a 91% increased risk of oral cavity and oropharynx cancer (RR = 1.91, 95% CI [1.19-3.06]). Sensitivity analysis indicated that no significant variation in combined RR by excluding any of the study, confirming the stability of present results.

CONCLUSIONS

The present meta-analysis suggested that high consumption of processed meat was significantly associated with an increased risk of oral cavity and oropharynx cancer, while there was no significantly association between total meat, red meat or white meat and the risk of oral cavity and oropharynx cancer. More prospective cohort studies are warranted to confirm these associations.

The association between fish consumption and risk of renal cancer: a meta-analysis of observational studies

Background

Several case-control studies and cohort studies have investigated the association between fish intake and renal cancer risk, however, they yielded conflicting results. To our knowledge, a comprehensive assessment of the association between fish consumption and risk of renal cancer has not been reported. Hence, we conducted a systematic literature search and meta-analysis to quantify the association between fish consumption and renal cancer.

Methods

A systematic search was performed using the PubMed, Embase, and Cochrane Library Central database for case-control and cohort studies that assessed fish intake and risk of renal cancer. Two authors independently assessed eligibility and extracted data. Fixed-effect and random-effect models were used to estimate summary relative risks (RR) and the corresponding 95% confidence intervals (CIs). Subgroup analyses, sensitivity analysis and cumulative meta-analysis were also performed.

Results

A total of 12 case-control studies and three cohort studies published between 1990 and 2011 were included in the meta-analysis, involving 9,324 renal cancer cases and 608,753 participants. Meta-analysis showed that fish consumption did not significantly affect the risk of renal cancer (RR=0.99, 95% CI [0.92,1.07]). In our subgroup analyses, the results were not substantially affected by study design, region, gender, and confounder adjustments. Furthermore, sensitivity analysis confirmed the stability of results.

Conclusions

The present meta-analysis suggested that there was no significant association between fish consumption and risk of renal cancer. More in-depth studies are warranted to report more detailed results, including stratified results by fish type, preparation method, and gender.

Snack frequency: associations with healthy and unhealthy food choices

Objective

We examined associations between snack frequency, sociodemographic characteristics, BMI, dietary and eating behaviour. In order to identify whether various subgroups of high-frequency snack consumers exist, we investigated underlying food patterns and lifestyle factors.

Design

The data were based on the Swiss Food Panel Questionnaire of 2010, which included an FFQ, questions relating to sociodemographics and lifestyle factors. Data were examined using ANOVA, regression analysis and hierarchical cluster analysis. Gender differences were also investigated in the analysis of the data.

Setting

A sample of 6189 adults participating in the Swiss Food Panel filled in a questionnaire (response rate 30 %).

Subjects

The sample consisted of both men and women, with a mean age of 54·4 (sd 13·5) years.

Results

There was no association between snack frequency and BMI. Consumption frequency of sweets and savouries as well as fruit intake increased with increasing snack frequency. Additionally, three different subgroups of high-frequency snack consumers could be revealed: healthy, moderate and unhealthy dietary-pattern groups. The latter included respondents who were less health-conscious and was characterized by high alcohol consumption frequency, daily breakfast skipping and watching television during the main meal.

Conclusions

High snack frequency occurred in the context of healthy as well as unhealthy dietary behaviour and lifestyle patterns. Women made healthier dietary food choices and were more likely to consume fruits as snacks, while men chose unhealthy foods, such as sweets and savouries, more often.

A new, simple method for the production of meat-curing pigment under optimised conditions using response surface methodology

The production of cured meat pigment using nitrite and ascorbate in acidic conditions was evaluated. HCl, ascorbate and nitrite concentrations were optimised at three levels using the response surface method (RSM). The effects of process variables on the nitrosoheme yield, the wavelength of maximum absorbance (λ(max)), and L*, a* and b* values were evaluated. The response surface equations indicate that variables exerted a significant effect on all dependent factors. The optimum combinations for the reaction were HCl=-0.8, ascorbate=0.46 and nitrite=1.00 as coded values for conversion of 1mM hemin to nitrosoheme, by which a pigment yield of 100%, which was similar to the predicted value of 99.5%, was obtained. Likewise, the other parameters were not significantly different from predicted values as the λ(max), L*, a* and b* values were 558 nm, 47.03, 45.17 and 17.20, respectively. The structure of the pigment was identified using FTIR and ESI/MS.

Large prospective investigation of meat intake, related mutagens, and risk of renal cell carcinoma

BACKGROUND

The evidence for meat intake and renal cell carcinoma (RCC) risk is inconsistent. Mutagens related to meat cooking and processing, and variation by RCC subtype may be important to consider.

OBJECTIVE

In a large US cohort, we prospectively investigated intake of meat and meat-related compounds in relation to risk of RCC, as well as clear cell and papillary RCC histologic subtypes.

DESIGN

Study participants (492,186) completed a detailed dietary assessment linked to a database of heme iron, heterocyclic amines (HCA), polycyclic aromatic hydrocarbons (PAHs), nitrate, and nitrite concentrations in cooked and processed meats. Over 9 (mean) y of follow-up, we identified 1814 cases of RCC (498 clear cell and 115 papillary adenocarcinomas). HRs and 95% CIs were estimated within quintiles by using multivariable Cox proportional hazards regression.

RESULTS

Red meat intake [62.7 g (quintile 5) compared with 9.8 g (quintile 1) per 1000 kcal (median)] was associated with a tendency toward an increased risk of RCC [HR: 1.19; 95% CI: 1.01, 1.40; P-trend = 0.06] and a 2-fold increased risk of papillary RCC [P-trend = 0.002]. Intakes of benzo(a)pyrene (BaP), a marker of PAHs, and 2-amino-1-methyl-6-phenyl-imidazo[4,5-b]pyridine (PhIP), an HCA, were associated with a significant 20-30% elevated risk of RCC and a 2-fold increased risk of papillary RCC. No associations were observed for the clear cell subtype.

CONCLUSIONS

Red meat intake may increase the risk of RCC through mechanisms related to the cooking compounds BaP and PhIP. Our findings for RCC appeared to be driven by strong associations with the rarer papillary histologic variant. This study is registered at clinicaltrials.gov as NCT00340015.

Epidemiology of renal cell cancer

Renal cell cancer (RCC) is increasingly diagnosed at an early stage in many countries, which likely contributes to the recent leveling of RCC mortality in the United States and many European countries. However, over all stages nearly 50% of the patients die within 5 years after diagnosis. Smoking and obesity may account for approximately 40% of all incidental cases in high-risk countries. Besides obesity, rising prevalence of hypertension may play a growing role. Several other occupational and lifestyle factors may also affect the risk of RCC. Genetic variations may be an important factor in the differing incidence among populations.

Meat-cooking mutagens and risk of renal cell carcinoma

BACKGROUND

High-temperature cooked meat contains two families of carcinogens, heterocyclic amines (HCAs) and polycyclic aromatic hydrocarbons (PAHs). Given the kidneys' role in metabolism and urinary excretion of these compounds, we investigated meat-derived mutagens, as well as meat intake and cooking methods, in a population-based case-control study conducted in metropolitan Detroit and Chicago.

METHODS

Newly diagnosed, histologically confirmed adenocarcinoma of the renal parenchyma (renal cell carcinoma (RCC)) cases (n=1192) were frequency matched on age, sex, and race to controls (n=1175). The interviewer-administered Diet History Questionnaire (DHQ) included queries for meat-cooking methods and doneness with photographic aids. Levels of meat mutagens were estimated using the DHQ in conjunction with the CHARRED database.

RESULTS

The risk of RCC increased with intake of barbecued meat (P(trend)=0.04) and the PAH, benzo(a)pyrene (BaP) (multivariable-adjusted odds ratio and 95% confidence interval, highest vs lowest quartile: 1.50 (1.14, 1.95), P(trend)=0.001). With increasing BaP intake, the risk of RCC was more than twofold in African Americans and current smokers (P(interaction)<0.05). We found no association for HCAs or overall meat intake.

CONCLUSION

BaP intake, a PAH in barbecued meat, was positively associated with RCC. These biologically plausible findings advocate further epidemiological investigation into dietary intake of BaP and risk of RCC.

Contemporary epidemiology of renal cell carcinoma: perspectives of primary prevention

OBJECTIVE

Epidemiological research of recent years has produced evidence for a role of lifestyle-associated risk factors in the etiology of renal cell carcinoma (RCC), the most common renal tumor. In this review, we give an overview of recent trends in incidence and mortality and summarize the current knowledge on risk factors of RCC.

METHODS

Data on incidence and mortality in the literature were reviewed. Global incidence data were derived from the Globocan database. A literature review of epidemiological studies on risk factors of kidney cancer was performed, with special emphasis on recent studies with high level of evidence, i.e., meta-analyses and prospective cohort studies.

RESULTS

The incidence of renal malignancies has increased over recent decades in the context of the more widespread use of diagnostic imaging. However, time trends and geographic variations in incidence and mortality may also relate to changes in the prevalence of risk factors. Cigarette smoking, excess body weight and uncontrolled blood pressure are the most important and modifiable risk factors for RCC with a high prevalence in the general population. Moreover, dietary habits associated with a Western lifestyle were proposed as potential risk factors, but no food or food group has consistently been related to RCC risk.

CONCLUSION

Based on the current evidence, reductions in the prevalence of cigarette smoking, overweight and hypertension are preventive strategies for RCC. More research is needed to establish the underlying mechanisms linking these risk factors and renal carcinogenesis.

Quantitative assessment of red meat or processed meat consumption and kidney cancer

OBJECTIVE

To conduct a quantitative assessment of red meat or processed meat consumption and kidney cancer.

METHODS

We extracted data from 12 case-control studies, three cohort studies, and the Pooling Project of Diet and Cancer publication for which 13 international cohorts were evaluated. Random effects meta-analysis models were used to calculate summary relative risk estimates (SRRE) based on high vs. low intake values. Sensitivity and influence analyses were conducted, including assessments of heterogeneity.

RESULTS

The SRRE for all studies that reported results for red meat (included variables labeled 'red meat' or single red meat items, such as beef, pork, or liver) was 1.12 (95% CI: 0.98-1.29; p-value for heterogeneity=0.015), and the SRRE using only data from prospective cohorts was 1.02 (95% CI: 0.91-1.15) with minimal heterogeneity (p=0.741). Similarly, in a meta-analysis of the five studies that simultaneously adjusted for smoking, BMI, and total energy intake, the SRRE for red meat was 1.02 (95% CI: 0.91-1.15). No significant association was observed in the meta-analysis of processed meat consumption (SRRE=1.07; 95% CI: 0.94-1.23), although a significant association was observed when only data from cohort studies were analyzed (SRRE=1.19; 95% CI: 1.03-1.37).

CONCLUSIONS

Although many of the summary results were positive, all were weak in magnitude, most were not statistically significant, and associations were attenuated among studies that adjusted for key potential confounding factors. In summary, the findings of this meta-analysis are not supportive of an independent relation between red or processed meat intake and kidney cancer.

Nutrient and fiber intake and risk of renal cell carcinoma

This study examines the association between nutrient and fiber intake and the risk of renal cell carcinoma (RCC). Between 1994 and 1997 in 8 Canadian provinces, mailed questionnaires were completed by 1,138 incident, histologically confirmed cases of RCC and 5,039 population controls. Measurement included information on socioeconomic status, lifestyle habits, and diet. A 69-item food frequency questionnaire provided data on eating habits 2 yr before data collection. Odds ratios (ORs) and 95% confidence intervals were derived through unconditional logistic regression. Intakes of total fat, saturated fat, monounsaturated fat, trans-fat, and cholesterol were associated with the risk of RCC; the ORs for the highest vs. the lowest quartile were 1.67, 1.53 and 1.46, 1.31, and 1.48, respectively. The positive association was apparently stronger in women, overweight or obese, and never smokers. Sucrose was related to the risk of RCC. High fiber intake was inversely associated with RCC risk. No association was found with intake of total protein and polyunsaturated fat, n-3 and n-6 polyunsaturated fatty acids, and total carbohydrates. The results were consistent across strata of sex, tobacco, and BMI. The findings suggest that a diet low in fats and cholesterol and rich in fiber could favorably affect the risk of RCC.

Fat, protein, and meat consumption and renal cell cancer risk: a pooled analysis of 13 prospective studies

BACKGROUND

Results of several case-control studies suggest that high consumption of meat (all meat, red meat, or processed meat) is associated with an increased risk of renal cell cancer, but only a few prospective studies have examined the associations of intakes of meat, fat, and protein with renal cell cancer.

METHODS

We conducted a pooled analysis of 13 prospective studies that included 530,469 women and 244,483 men and had follow-up times of up to 7-20 years to examine associations between meat, fat, and protein intakes and the risk of renal cell cancer. All participants had completed a validated food frequency questionnaire at study entry. Using the primary data from each study, we calculated the study-specific relative risks (RRs) for renal cell cancer by using Cox proportional hazards models and then pooled these RRs by using a random-effects model. All statistical tests were two-sided.

RESULTS

A total of 1,478 incident cases of renal cell cancer were identified (709 in women and 769 in men). We observed statistically significant positive associations or trends in pooled age-adjusted models for intakes of total fat, saturated fat, monounsaturated fat, polyunsaturated fat, cholesterol, total protein, and animal protein. However, these associations were attenuated and no longer statistically significant after adjusting for body mass index, fruit and vegetable intake, and alcohol intake. For example, the pooled age-adjusted RR of renal cell cancer for the highest vs the lowest quintile of intake for total fat was 1.30 (95% confidence interval [CI] = 1.08 to 1.56; P(trend) = .001) and for total protein was 1.17 (95% CI = 0.99 to 1.38; P(trend) = .02). By comparison, the pooled multivariable RR for the highest vs the lowest quintile of total fat intake was 1.10 (95% CI = 0.92 to 1.32; P(trend) = .31) and of total protein intake was 1.06 (95% CI = 0.89 to 1.26; P(trend) = .37). Intakes of red meat, processed meat, poultry, or seafood were not associated with the risk of renal cell cancer.

CONCLUSIONS

Intakes of fat and protein or their subtypes, red meat, processed meat, poultry, and seafood are not associated with risk of renal cell cancer.

Meat and fish consumption and cancer in Canada

In this study, we examined the association between meat and fish intake and the risk of various cancers. Mailed questionnaires were completed by 19,732 incident, histologically confirmed cases of cancer of the stomach, colon, rectum, pancreas, lung, breast, ovary, prostate, testis, kidney, bladder, brain, non-Hodgkin's lymphomas (NHL), and leukemia and 5,039 population controls between 1994 and 1997 in 8 Canadian provinces. Measurement included information on socioeconomic status, lifestyle habits, and diet. A 69-item food frequency questionnaire provided data on eating habits 2 yr before data collection. Odds ratios and 95% confidence intervals were derived through unconditional logistic regression. Total meat and processed meat were directly related to the risk of stomach, colon, rectum, pancreas, lung, breast (mainly postmenopausal), prostate, testis, kidney, bladder, and leukemia. Red meat was significantly associated with colon, lung (mainly in men), and bladder cancer. No relation was observed for cancer of the ovary, brain, and NHL. No consistent excess risk emerged for fish and poultry, which were inversely related to the risk of a number of cancer sites. These findings add further evidence that meat, specifically red and processed meat, plays an unfavorable role in the risk of several cancers. Fish and poultry appear to be favorable diet indicators.

Meat consumption and cancer risk

The authors review the key studies on the association between meat intake and cancer risk, including a new prospective cohort study by Amanda Cross and colleagues published inPLoS Medicine.

A prospective study of red and processed meat intake in relation to cancer risk

BACKGROUND

Red meat and processed meat have been associated with carcinogenesis at several anatomic sites, but no prospective study has examined meat intake in relation to a range of malignancies. We investigated whether red or processed meat intake increases cancer risk at a variety of sites.

METHODS AND FINDINGS

The National Institutes of Health (NIH)-AARP (formerly the American Association for Retired Persons) Diet and Health Study is a cohort of approximately 500,000 people aged 50-71 y at baseline (1995-1996). Meat intake was estimated from a food frequency questionnaire administered at baseline. Cox proportional hazards regression was used to estimate hazard ratios and 95% confidence intervals within quintiles of red and processed meat intake. During up to 8.2 y of follow-up, 53,396 incident cancers were ascertained. Statistically significant elevated risks (ranging from 20% to 60%) were evident for esophageal, colorectal, liver, and lung cancer, comparing individuals in the highest with those in the lowest quintile of red meat intake. Furthermore, individuals in the highest quintile of processed meat intake had a 20% elevated risk for colorectal and a 16% elevated risk for lung cancer.

CONCLUSIONS

Both red and processed meat intakes were positively associated with cancers of the colorectum and lung; furthermore, red meat intake was associated with an elevated risk for cancers of the esophagus and liver.