Risk factors for bladder cancer: a case-control study in northeast China

Is there a promoting role for artificial sweeteners in the evolution of bladder cancer? A meta-analysis of current literature

INTRODUCTION

Urinary bladder cancer is a frequent neoplasia in the urogenital system. Ageing and smoking are the two main risk factors, however, some chemical agents such as artificial sweeteners could act as initiators or promoters.

EVIDENCE ACQUISITION

After identifying trends in scientific literature, we conducted a wide search in PubMed database and a meta-analysis was performed on extracted data to determine the role of artificial sweeteners in the development of urinary bladder cancer.

EVIDENCE SYNTHESIS

Twenty-one full reports were enrolled from screening of PubMed database into final analysis involving 116,568 subjects in comparisons. Overall, 13,682 and 102,886 cases were identified for bladder cancer patients and healthy controls, respectively. Among artificial sweetener users, 12.5% was the incidence of bladder cancer. In the control group, 11.2% of cases suffered from urothelial carcinoma of the bladder. About 40.7% of the patients suffering from urinary neoplasms and 37.8% of the healthy cases were artificial sweetener users, respectively. There were only minor differences in overall descriptive data. The incidence of urinary bladder cancer among artificial sweetener users and control cases showed no risk difference (RD: 0.00, CI: -0.06 to 0.06). The frequency of artificial sweetener use among patients suffering from urinary bladder neoplasms and healthy subjects was compared which showed equal occurrences (OR: 0.96, CI: 0.79 to 1.17).

CONCLUSIONS

According to our results, the carcinogenic risk of artificial sweeteners is not proven. Saccharin should not be kept as a promoter in urothelial malignant transformation.

Non-sugar sweeteners and cancer: Toxicological and epidemiological evidence

Several toxicological and epidemiological studies were published during the last five decades on non-sugar sweeteners (NSS) and cancer. Despite the large amount of research, the issue still continues to be of interest. In this review, we provided a comprehensive quantitative review of the toxicological and epidemiological evidence on the possible relation between NSS and cancer. The toxicological section includes the evaluation of genotoxicity and carcinogenicity data for acesulfame K, advantame, aspartame, cyclamates, saccharin, steviol glycosides and sucralose. The epidemiological section includes the results of a systematic search of cohort and case-control studies. The majority of the 22 cohort studies and 46 case-control studies showed no associations. Some risks for bladder, pancreas and hematopoietic cancers found in a few studies were not confirmed in other studies. Based on the review of both the experimental data on genotoxicity or carcinogenicity of the specific NSS evaluated, and the epidemiological studies it can be concluded that there is no evidence of cancer risk associated to NSS consumption.

Cigarette smoking and risk of bladder cancer: a dose-response meta-analysis

INTRODUCTION

The disease burden of bladder cancer is increasing worldwide; therefore, to deal with this situation, many studies on bladder cancer have been carried out extensively. Among these studies, the risk factors studies may provide a possible way to reduce the incidence of bladder cancer. Meta-analyses and original researches have confirmed that smoking is a risk factor of bladder cancer. However, the specific dose-response relationship between smoking and bladder cancer risk was still unclear. This meta-analysis addresses this research gap by summarizing the accumulated evidences, quantitatively.

METHODS

Relevant studies were obtained by searching PubMed, Embase and Web of Science database since inception until August 10, 2021, without restrictions. To obtain more comprehensive data, reference lists of identified articles were also browsed. Studies that reported risk estimates (relative risks (RR) or odds ratio (OR)) with 95% confidence intervals (CIs) focusing on the association between cigarette smoking and risk of bladder cancer were included in a dose-response meta-analysis.

RESULTS

A non-linear dose-response relationship was confirmed between cigarette smoking and risk of bladder cancer on the basis of 8 cohorts and 44 case-control studies. The summary relative risk of developing bladder cancer for 1 more cigarettes/day (7 cohorts and 24 case-control studies) was 1.039 (95% CI 1.038-1.040, I² = 0%), for 1 more pack-year (3 cohorts and 21 case-control studies) was 1.017(95% CI 1.016-1.019, I² = 0%) and for 1 more year of exposure (16 case-control studies) was 1.021 (95% CI 1.020-1.023, I² = 0%).

CONCLUSION

A positive non-linear dose-response relationship is confirmed between all smoking intensity, pack-years of smoking, smoking duration(years) and the risk of bladder cancer, but the plateau only occurred when smoking intensity reached 20 cigarettes/day. Further studies should report more detailed results, including those for subtypes of gender, age, region and be stratified by other risk factors to rule out residual confounding.

Association between intake of non-sugar sweeteners and health outcomes: systematic review and meta-analyses of randomised and non-randomised controlled trials and observational studies

OBJECTIVE

To assess the association between intake of non-sugar sweeteners (NSS) and important health outcomes in generally healthy or overweight/obese adults and children.

DESIGN

Systematic review following standard Cochrane review methodology.

DATA SOURCES

Medline (Ovid), Embase, Cochrane CENTRAL, WHO International Clinical Trials Registry Platform, Clinicaltrials.gov, and reference lists of relevant publications.

ELIGIBILITY CRITERIA FOR SELECTING STUDIES

Studies including generally healthy adults or children with or without overweight or obesity were eligible. Included study designs allowed for a direct comparison of no intake or lower intake of NSS with higher NSS intake. NSSs had to be clearly named, the dose had to be within the acceptable daily intake, and the intervention duration had to be at least seven days.

MAIN OUTCOME MEASURES

Body weight or body mass index, glycaemic control, oral health, eating behaviour, preference for sweet taste, cancer, cardiovascular disease, kidney disease, mood, behaviour, neurocognition, and adverse effects.

RESULTS

The search resulted in 13 941 unique records. Of 56 individual studies that provided data for this review, 35 were observational studies. In adults, evidence of very low and low certainty from a limited number of small studies indicated a small beneficial effect of NSSs on body mass index (mean difference -0.6, 95% confidence interval -1.19 to -0.01; two studies, n=174) and fasting blood glucose (-0.16 mmol/L, -0.26 to -0.06; two, n=52). Lower doses of NSSs were associated with lower weight gain (-0.09 kg, -0.13 to -0.05; one, n=17 934) compared with higher doses of NSSs (very low certainty of evidence). For all other outcomes, no differences were detected between the use and non-use of NSSs, or between different doses of NSSs. No evidence of any effect of NSSs was seen on overweight or obese adults or children actively trying to lose weight (very low to moderate certainty). In children, a smaller increase in body mass index z score was observed with NSS intake compared with sugar intake (-0.15, -0.17 to -0.12; two, n=528, moderate certainty of evidence), but no significant differences were observed in body weight (-0.60 kg, -1.33 to 0.14; two, n=467, low certainty of evidence), or between different doses of NSSs (very low to moderate certainty).

CONCLUSIONS

Most health outcomes did not seem to have differences between the NSS exposed and unexposed groups. Of the few studies identified for each outcome, most had few participants, were of short duration, and their methodological and reporting quality was limited; therefore, confidence in the reported results is limited. Future studies should assess the effects of NSSs with an appropriate intervention duration. Detailed descriptions of interventions, comparators, and outcomes should be included in all reports.

SYSTEMATIC REVIEW REGISTRATION

Prospero CRD42017047668.

Health outcomes of non-nutritive sweeteners: analysis of the research landscape

BACKGROUND

Food products containing non-nutritive sweeteners (NNSs) instead of sugar have become increasingly popular in the last decades. Their appeal is obviously related to their calorie-free sweet taste. However, with the dramatic increase in their consumption, it is reasonable and timely to evaluate their potential health benefits and, more importantly, potential adverse effects. The main aim of this scoping review was to map the evidence about health outcomes possibly associated with regular NNS consumption by examining the extent, range, and nature of research activity in this area.

METHODS

We systematically searched Ovid MEDLINE, EMBASE and the Cochrane CENTRAL databases for studies on NNSs (artificial sweeteners or natural, non-caloric sweeteners, either used individually or in combination) using text terms with appropriate truncation and relevant indexing terms. All human studies investigating any health outcomes of a NNS intervention or exposure were eligible for inclusion. No studies were excluded based on language, study design or methodological quality. Data for each health outcome were summarized in tabular form and were discussed narratively.

RESULTS

Finally, we included 372 studies in our scoping review, comprising 15 systematic reviews, 155 randomized controlled trials (RCTs), 23 non-randomized controlled trials, 57 cohort studies, 52 case-control studies, 28 cross sectional studies and 42 case series/case reports. In healthy subjects, appetite and short term food intake, risk of cancer, risk of diabetes, risk of dental caries, weight gain and risk of obesity are the most investigated health outcomes. Overall there is no conclusive evidence for beneficial and harmful effects on those outcomes. Numerous health outcomes including headaches, depression, behavioral and cognitive effects, neurological effects, risk of preterm delivery, cardiovascular effects or risk of chronic kidney disease were investigated in fewer studies and further research is needed. In subjects with diabetes and hypertension, the evidence regarding health outcomes of NNS use is also inconsistent.

CONCLUSIONS

This scoping review identifies the needs for future research to address the numerous evidence gaps related to health effects of NNSs use.It also specifies the research questions and areas where a systematic review with meta-analyses is required for the proper evaluation of health outcomes associated to regular NNSs consumption.

Intake of fruit and vegetables and risk of bladder cancer: a dose-response meta-analysis of observational studies

BACKGROUND

Observational studies suggest an association between fruit and vegetables intake and risk of bladder cancer, but the results are controversial.

METHODS

We therefore summarized the evidence from observational studies in categorical, linear, and nonlinear, dose-response meta-analysis. Pertinent studies were identified by searching EMBASE and PubMed from their inception to August 2013.

RESULTS

Thirty-one observational studies involving 12,610 cases and 1,121,649 participants were included. The combined rate ratio (RR, 95 % CI) of bladder cancer for the highest versus lowest intake was 0.83 (0.69-0.99) for total fruit and vegetables, 0.81 (0.70-0.93) for total vegetables, 0.77 (0.69-0.87) for total fruit, 0.84 (0.77-0.91) for cruciferous vegetables, 0.79 (0.68-0.91) for citrus fruits, and 0.74 (0.66-0.84) for yellow-orange vegetables. Subgroup analysis showed study design and gender as possible sources of heterogeneity. A nonlinear relationship was found of citrus fruits intake with risk of bladder cancer (P for nonlinearity = 0.018), and the RRs (95 % CI) of bladder cancer were 0.87 (0.78-0.96), 0.80 (0.67-0.94), 0.79 (0.66-0.94), 0.79 (0.65-0.96), and 0.79 (0.64-0.99) for 30, 60, 90, 120, and 150 g/day. A nonlinear relationship was also found of yellow-orange vegetable intake with risk of bladder cancer risk (P for nonlinearity = 0.033). Some evidence of publication bias was observed for fruit, citrus fruits, and yellow-orange vegetables.

CONCLUSION

This meta-analysis supports the hypothesis that intakes of fruit and vegetables may reduce the risk of bladder cancer. Future well-designed studies are required to confirm this finding.

A meta-analysis of tea consumption and the risk of bladder cancer

OBJECTIVE

Previous studies on the association between tea consumption and bladder cancer risk have only illustrated contradictory results. The role of tea in bladder carcinogenesis still remains conflicting. In order to illustrate the potential relationship between tea consumption and bladder cancer, a meta-analysis of case-control and cohort studies was conducted.

METHODS

Eligible studies were retrieved via both computerized searches and review of references. Stratified analyses on types of tea, gender, study design, ethnicity and smoking status were performed. Fixed- or random-effect models were used to summarize the estimates of OR with 95% CIs.

RESULTS

Seventeen studies were eligible for our analysis. No statistical significance was detected between tea consumption and bladder cancer risk when comparing the highest with the lowest intake of tea (OR = 0.825, 95% CI 0.652-1.043). In the subgroup of green tea, we observed it illustrated a protective effect on bladder cancer (OR = 0.814, 95% CI 0.678-0.976).

CONCLUSION

Our analysis indicated that green tea may have a protective effect on bladder cancer in Asian people. Further studies need to be conducted to better clarify the biological mechanisms.

A meta-analysis of alcohol intake and risk of bladder cancer

OBJECTIVE

Epidemiologic studies have reported conflicting results relating alcohol intake to bladder cancer risk. A meta-analysis of cohort and case-control studies was conducted to pool the risk estimates of the association between alcohol intake and bladder cancer.

METHODS

Eligible studies were retrieved via both computer searches and review of references. We analyzed abstracted data with random effects models to obtain the summary risk estimates. Dose-response meta-analysis was performed for studies reporting categorical risk estimates for a series of exposure levels.

RESULTS

Nineteen studies met the inclusion criteria of the meta-analysis. No association with bladder cancer was observed in either overall alcohol intake group (OR = 1.00, 95% CI 0.89-1.10) or subgroups stratified by sex, study design, geographical region, or smoking status. However, in the analysis by specific beverages, both beer (OR = 0.86, 95% CI 0.76-0.96) and wine (OR = 0.85, 95% CI 0.71-1.00) consumption exhibited a negative dose-response relationship with bladder cancer.

CONCLUSION

The overall current literature on alcohol consumption and the risk of bladder cancer suggested no association, while the consumption of beer and wine was associated with reduced risk of bladder cancer. Further efforts should be made to confirm these findings and clarify the underlying biological mechanisms.

Evidence-based principles of bladder cancer and diet

Bladder cancer presents a substantial challenge to public health. Dietary factors influence the risk of bladder cancer incidence and recurrence and may offer innovative therapies for prevention. Agents associated with decreased risk of bladder cancer include carrots, selenium, cruciferous vegetables, and fruits. Dietary components associated with increased bladder cancer risk include pork, barbecued meats, fat, soy, and excessive coffee consumption. Although definitive clinical trials have yet to be performed, promotion of healthy lifestyle interventions based on dietary factors--increased vegetable and fruit intakes, decreased meat and fat intakes--should be considered in the care of patients with bladder cancer.

Alcohol, coffee, and bladder cancer risk: a review of epidemiological studies

The objective was to review epidemiological studies that evaluated the association between consumption of coffee and alcohol and urinary bladder cancer. We searched the Medline database for observational studies of bladder neoplasms that included information on coffee or alcohol drinking, and looked for papers quoted as references in reviews of risk factors for bladder cancer and in studies that had been selected for inclusion. Results from epidemiological studies allow excluding a strong association between coffee and bladder cancer. Several studies reported a moderate increase in risk in coffee drinkers as compared with nondrinkers, but no trend with dose has been established. Epidemiological data on alcohol drinking and bladder cancer are suggestive of no association, although findings were not always consistent. For both habits, an explanation of the moderate increase in risk observed in some investigations might be attributed to residual confounding by smoking, or to an association between alcohol, coffee, and yet unidentified risk factors for bladder cancer.

Nutrition, total fluid and bladder cancer

Bladder cancer is a major health concern for older males in Western populations. About 30 years ago there was a suggestion that nutrition may have a role in the aetiology of the disease. Although the literature has been accumulating since then, owing to heterogeneity between studies results have often been inconsistent and unclear. The aim of this paper was to present an updated summary of the scientific evidence on the association between nutrition, total fluid intake and bladder cancer. A search of computerized databases, PubMed, ISI, Embase and Cochrane Library, was conducted to identify all epidemiological studies published between 1966 and October 2007. The level of scientific evidence for the various nutritional factors and total fluid intake was ranked according to the number of studies reporting a statistically significant association and the existence of mechanistic evidence. The levels of association were based on a ranking of statistically significant relative risks. Fruit and yellow-orange vegetables, particularly carrots and selenium, are probably associated with a moderately reduced risk of bladder cancer. Citrus fruits and cruciferous vegetables were also identified as having a possible protective effect. Possible risk factors are salted and barbecued meat, pork, total fat, pickled vegetables, salt, soy products, spices and artificial sweeteners. No clear association could be determined for beef, eggs, processed meats and total fluid intake. In conclusion, specific fruit and vegetables may act to reduce the risk of bladder cancer. Future studies on bladder cancer should investigate the effect of food categorization, amount and gender.

Coffee and alcohol consumption and bladder cancer

Epidemiological studies on coffee, alcohol and bladder cancer risk published up to 2007 were reviewed. Coffee drinkers have a moderately higher relative risk of bladder cancer compared to non-drinkers. The association may partly be due to residual confounding by smoking or dietary factors, but the interpretation remains open to discussion, although the absence of dose and duration-risk relations weighs against the presence of a causal association. Most studies of alcohol and bladder cancer found no association, with some studies finding a direct and other an inverse one. This again may be due to differential confounding effect of tobacco smoking--the major risk factor for bladder cancer--in various populations. Thus, epidemiological findings on the relation between alcohol drinking and bladder cancer exclude any meaningful association.

Artificial sweeteners--do they bear a carcinogenic risk?

Artificial sweeteners are added to a wide variety of food, drinks, drugs and hygiene products. Since their introduction, the mass media have reported about potential cancer risks, which has contributed to undermine the public's sense of security. It can be assumed that every citizen of Western countries uses artificial sweeteners, knowingly or not. A cancer-inducing activity of one of these substances would mean a health risk to an entire population. We performed several PubMed searches of the National Library of Medicine for articles in English about artificial sweeteners. These articles included 'first generation' sweeteners such as saccharin, cyclamate and aspartame, as well as 'new generation' sweeteners such as acesulfame-K, sucralose, alitame and neotame. Epidemiological studies in humans did not find the bladder cancer-inducing effects of saccharin and cyclamate that had been reported from animal studies in rats. Despite some rather unscientific assumptions, there is no evidence that aspartame is carcinogenic. Case-control studies showed an elevated relative risk of 1.3 for heavy artificial sweetener use (no specific substances specified) of >1.7 g/day. For new generation sweeteners, it is too early to establish any epidemiological evidence about possible carcinogenic risks. As many artificial sweeteners are combined in today's products, the carcinogenic risk of a single substance is difficult to assess. However, according to the current literature, the possible risk of artificial sweeteners to induce cancer seems to be negligible.

Alcohol Consumption and the Risk of Bladder Cancer in the Framingham Heart Study

The association between alcohol consumption and bladder cancer is controversial. We used data from 10,125 participants in the Framingham Heart Study to assess the association between total and beverage-specific alcohol consumption and the risk of bladder cancer. For each case of bladder cancer, up to five control subjects were selected and matched on major confounders using a risk set method. We used conditional logistic regression to assess the risk of bladder cancer according to categories of alcohol consumption. During a mean follow-up of 27.3 +/- 10.1 years, there were 126 incident cases of bladder cancer. There was no statistically significant association between alcohol consumption and risk of bladder cancer (P(trend) =.3). In beverage-specific analyses, beer consumption was associated with a reduced risk of bladder cancer (P(trend) =.03), whereas wine (P(trend) =.7) and spirit (P(trend) =.2) consumption were not. Our data suggest that total and beverage-specific alcohol consumption are not associated with an increased risk of bladder cancer.

Epidemiologic evidence of the protective effect of fruit and vegetables on cancer risk

BACKGROUND

Diets rich in fruit and vegetables have been recommended for preventing cancer. The evidence supporting this recommendation is based on observational studies, although results of several prospective studies have cast some doubts on whether fruit and vegetables are associated with cancer risk reduction.

OBJECTIVE

We sought to summarize evidence from case-control and prospective studies on fruit and vegetable intake and cancer risk with a meta-analytic approach.

DESIGN

Published case-control and cohort studies that reported on total vegetable and fruit intake and risk of cancer of several sites were included. Relative risks were estimated by using linear logistic regression models.

RESULTS

Case-control studies overall support a significant reduction in the risks of cancers of the esophagus, lung, stomach, and colorectum associated with both fruit and vegetables; breast cancer is associated with vegetables but not with fruit; and bladder cancer is associated with fruit but not with vegetables. The overall relative risk estimates from cohort studies suggest a protective effect of both fruit and vegetables for most cancer sites considered, but the risk reduction is significant only for cancers of the lung and bladder and only for fruit.

CONCLUSIONS

Prospective studies provide weaker evidence than do case-control studies of the association of fruit and vegetable consumption with reduced cancer risk. The discrepancies may be related to recall and selection biases in case-control studies. In contrast, the association may have been underestimated in prospective studies because of the combined effects of imprecise dietary measurements and limited variability of dietary intakes within each cohort.

Defining alcohol-related fatal medical conditions for social-cost studies in western societies: an update of the epidemiological evidence

OBJECTIVES

To elaborate a state-of-the-art list of alcohol-related fatal medical conditions for future social-cost studies in Western societies.

METHODS

Three major social-cost studies were compared with regard to their respective section on fatal health effects attributable to long-term as well as short-term use of alcohol. On discordant conditions, a systematic literature search was conducted in the Medline and ETOH databases.

RESULTS

There is no consensus between social-cost studies with respect to alcohol-related causes of mortality. Based on the recent epidemiological evidence on alcohol and health, this paper suggests an up-to-date list of fatal medical conditions for which the causal relationship has been established with sufficient scientific evidence. A further investigation is needed, however, to reestimate relative risks by meta-analysis.

CONCLUSIONS

Evaluating new epidemiological evidence regularly is necessary for the purpose of up-to-date social-cost studies.

Foods and nutrients in relation to bladder cancer risk: a case-control study in Aichi Prefecture, Central Japan

To elucidate the role of diet in the etiology of bladder cancer, we conducted a case-control study from 1996 to 1999 in Aichi Prefecture, Central Japan. Cases were patients newly diagnosed with bladder cancer, and one hospital control was selected for each case, matching gender, age, and hospital. A well-validated food frequency questionnaire was adopted to estimate intakes of nutrients and food groups. Odds ratios (ORs) adjusted for smoking and occupational history were computed using conditional logistic models. The analyses based on 297 cases and 295 controls revealed the following. 1) The more the intake of milk and dairy products, the lower the OR; the ORs across quartiles in all subjects were 1.02, 0.73, and 0.52. Fruit intake was negatively associated with the risk, particularly in men (ORs across quartiles = 0.76, 0.77, and 0.52). Green-yellow vegetables were associated with a decreased risk in the highest quartile of consumption in men (OR = 0.57). 2) Dietary intakes of retinol and saturated fatty acids were related to a reduced risk in all subjects (ORs across quartiles = 0.75, 0.54, and 0.66 and 0.55, 0.54, and 0.60, respectively). Monounsaturated fatty acids had an inverse association with bladder cancer risk in men.

Tea consumption: fluid intake and bladder cancer risk in Southern Taiwan

OBJECTIVES

To determine whether tea consumption and intake of other beverages increases bladder cancer risk.

METHODS

A case-control study was conducted in Kaohsiung, Taiwan between August 1996 and June 1997. Index patients studied were consecutive patients with histologically confirmed, newly diagnosed bladder cancer in two major hospitals. For each patient, 4 controls were selected from patients with non-neoplastic and nonurologic diseases undergoing surgical operations in the same hospital and individually matched by sex, age, and date of admission. Using a structured questionnaire, a trained interviewer interviewed 40 patients and 160 controls. Conditional logistic regression analysis adjusting for ethnicity, family history, and smoking status and matching variables were used to estimate the odds ratio (OR) and 95% confidence interval (CI).

RESULTS

Tea consumption overall was associated with increased bladder cancer risk (OR 3.29, 95% CI 1.34 to 8.05). Compared with non-tea drinkers, the odds ratios of bladder cancer for oolong tea drinkers was 3.00 (95% CI 1.20 to 7.47); for non-oolong tea drinkers (black and/or other green tea), it was 14.86 (95% CI 2.13 to 103.83). The risk was greater among those who began to drink tea before age 40 (OR 9.50, 95% CI 2.39 to 37.75) and those who had been drinking tea for more than 30 years (OR 17.75, 95% CI 3.00 to 105.17). Coffee, tap water, and alcohol consumption were associated with a slightly increased risk, and both soy juice and rice juice consumption were associated with reduced risk; none of these odds ratio estimates were statistically significant, however.

CONCLUSIONS

Our results suggest that tea consumption is associated with an increased risk of bladder cancer.