Diet and Bladder Cancer: A Case–Control Study

Dietary fats and their sources in association with the risk of bladder cancer: A pooled analysis of 11 prospective cohort studies

The effects of fat intake from different dietary sources on bladder cancer (BC) risk remains unidentified. Therefore, the present study aimed to investigate the association between fat intakes and BC risk by merging world data on this topic. Data from 11 cohort studies in the BLadder cancer Epidemiology and Nutritional Determinants (BLEND) study, provided sufficient information on fat intake for a total of 2731 BC cases and 544 452 noncases, which yielded 5 400 168 person-years of follow-up. Hazard ratios (HRs), with corresponding 95% confidence intervals (CIs), were estimated using Cox-regression models stratified on cohort. Analyses were adjusted for total energy intake in kilocalories, gender, smoking status (model-1) and additionally for sugar and sugar products, beers, wine, dressing and plant-based and fruits intakes (model-2). Among women, an inverse association was observed between mono-unsaturated fatty acids (MUFAs) and BC risk (HR comparing the highest with the lowest tertile: 0.73, 95% CI: 0.58-0.93, P-trend = .01). Overall, this preventative effect of MUFAs on BC risk was only observed for the nonmuscle invasive bladder cancer (NMIBC) subtype (HR: 0.69, 95% CI: 0.53-0.91, P-trend = .004). Among men, a higher intake of total cholesterol was associated with an increased BC risk (HR: 1.37, 95% CI: 1.16-1.61, P-trend = .01). No other significant associations were observed. This large prospective study adds new insights into the role of fat and oils in BC carcinogenesis, showing an inverse association between consumption of MUFAs and the development of BC among women and a direct association between higher intakes of dietary cholesterol and BC risk among men.

Genesis and Mechanism of Some Cancer Types and an Overview on the Role of Diet and Nutrition in Cancer Prevention

Cancer is a major disease with a high mortality rate worldwide. In many countries, cancer is considered to be the second most common cause of death after cardiovascular disease. The clinical management of cancer continues to be a challenge as conventional treatments, such as chemotherapy and radiation therapy, have limitations due to their toxicity profiles. Unhealthy lifestyle and poor dietary habits are the key risk factors for cancer; having a healthy diet and lifestyle may minimize the risk. Epidemiological studies have shown that a high fruit and vegetable intake in our regular diet can effectively reduce the risk of developing certain types of cancers due to the high contents of antioxidants and phytochemicals. In vitro and in vivo studies have shown that phytochemicals exert significant anticancer effects due to their free radical scavenging capacity potential. There has been extensive research on the protective effects of phytochemicals in different types of cancers. This review attempts to give an overview of the etiology of different types of cancers and assesses the role of phytonutrients in the prevention of cancers, which makes the present review distinct from the others available.

Association of Dietary Carrot Intake With Bladder Cancer Risk in a Prospective Cohort of 99,650 Individuals With 12.5 Years of Follow-Up

Previous studies have provided limited evidence for the effect of carrot intake on bladder cancer incidence. This study aimed to evaluate the association between carrot consumption and bladder cancer risk in the Prostate, Lung, Colorectal, and Ovarian Cancer (PLCO) Screening cohort. PLCO enrolled 154,897 participants between November 1993 and July 2001 from 10 clinical screening centers throughout the United States. Hazard ratios (HRs) and 95% confidence intervals (CIs) were estimated using Cox regression model adjusting for confounders. A meta-analysis was also performed based on all available prospective studies with DerSimonian and Laird random-effects model to calculate summary relative risk (RR) and 95% CI. After a median of 12.5 years of follow-up, 762 incident bladder cancer cases occurred. We found no statistically significant association between dietary carrot intake and bladder cancer risk. The multivariate-adjusted HR of bladder cancer for participants in the highest category of total carrot intake compared with those in the lowest category was 0.96 (95% CI: 0.76–1.22; P for trend = 0.436). Corresponding adjusted HR was 0.98 (95% CI 0.90–1.06) per 1 SD increment of carrot intake. A meta-analysis based on two previous cohort studies and our study also found no significant association between carrot intake and bladder cancer risk (Summary HR 1.02, 95% CI 0.95–1.10) without obvious heterogeneity between studies (P = 0.859, I² = 0.0%). In summary, analysis of the PLCO cohort did not provide evidence that dietary consumption of carrot was associated with the risk of bladder cancer.

Potato Consumption and Risk of Site-Specific Cancers in Adults: A Systematic Review and Dose-Response Meta-Analysis of Observational Studies

The etiology of cancer type may vary significantly due to anatomy, embryology, and physiology of the cancer site. Although the association between potato consumption and colorectal cancer (CRC) was summarized in a 2018 meta-analysis of 5 cohort studies, to the best of our knowledge, no meta-analysis has evaluated potato consumption in relation to multiple cancer sites in adults. Medline/PubMed, ISI Web of Knowledge, Scopus, and the Cochrane Database of Systematic Reviews were searched for relevant publications through August 2020. We selected cohort or case-control studies conducted in adults that reported risk estimates (relative risk [RRs], HRs, and ORs) of potato intake for any cancer type. Random effects meta-analyses compared high and low intake categories. Twenty prospective cohort studies (total n = 785,348) including 19,882 incident cases, and 36 case-control studies (21,822 cases; 66,502 controls) were included. Among cohort studies, we did not find an association between high versus low intake of total potato (white and yellow) consumption and overall cancers: 1.04 (95% CI: 0.96, 1.11; tau2 = 0.005, n = 18). We found no relation between total potato consumption (high compared with low intake) and risk of CRC, pancreatic cancer, colon, gastric, breast, prostate, kidney, lung, or bladder cancer in cohort or case-control studies. We did not find an association between high versus low consumption of potato preparations (boiled/fried/mashed/roasted/baked) and risk of gastrointestinal-, sex-hormone-, or urinary-related cancers in cohort or case-control studies. Certainty of the evidence was low for total cancer, CRC, colon, rectal, renal, pancreatic, breast, prostate, and lung cancer and very low for gastric and bladder cancer. In conclusion, potato intake or potato preparations were not associated with multiple cancer sites when comparing high and low intake categories. This finding was consistent with the findings from the 2018 meta-analysis regarding potato intake and risk of CRC.

Carrot intake and incidence of urothelial cancer: a systematic review and meta-analysis

Previous studies regarding the relationship between carrot intake and risk of urothelial cancer have reported conflicting results. Hence we performed a meta-analysis of eligible studies to summarize evidence on this association. A comprehensive search up to January 2017 was performed in PubMed, Web of Science, Scopus, EMBASE, Cochrane register, and Chinese National Knowledge Infrastructure (CNKI) databases. The combined odds ratio (OR) with 95% confidence interval (CI) for the highest versus the lowest intake of carrot was calculated. A total of six epidemiological studies consisting of four case-control and two cohort studies were included. Overall analysis indicated a significantly reduced risk of urothelial cancer for high intake of carrot (OR = 0.63, 95% CI 0.44-0.90). Obvious significant heterogeneity was observed among included studies (P < 0.001 for heterogeneity; I² = 79.6%). There was no significant publication bias by Begg's test (P = 0.348) or Egger's test (P = 0.130). In conclusion, this meta-analysis indicates that high intake of carrot is associated with a low incidence of urothelial cancer. Considering the limited included studies and huge heterogeneity, further large well-designed prospective cohort studies are warranted to confirm the findings from our meta-analysis.

Red and processed meat consumption and risk of bladder cancer: a dose-response meta-analysis of epidemiological studies

Background/objectives

Several epidemiological studies have analyzed the associations between red and processed meat and bladder cancer risk but the shape and strength of the associations are still unclear. Therefore, we conducted a dose–response meta-analysis to quantify the potential association between red and processed meat and bladder cancer risk.

Methods

Relevant studies were identified by searching the PubMed database through January 2016 and reviewing the reference lists of the retrieved articles. Results were combined using random-effects models.

Results

Five cohort studies with 3262 cases and 1,038,787 participants and 8 cases–control studies with 7009 cases and 27,240 participants met the inclusion criteria. Red meat was linearly associated with bladder cancer risk in case–control studies, with a pooled RR of 1.51 (95% confidence interval (CI) 1.13, 2.02) for every 100 g increase per day, while no association was observed among cohort studies (P heterogeneity across study design = 0.02). Based on both case–control and cohort studies, the pooled relative risk (RR) for every 50 g increase of processed meat per day was 1.20 (95% CI 1.06, 1.37) (P heterogeneity across study design = 0.22).

Conclusions

This meta-analysis suggests that processed meat may be positively associated with bladder cancer risk. A positive association between red meat and risk of bladder cancer was observed only in case–control studies, while no association was observe in prospective studies.

Electronic supplementary material

The online version of this article (doi:10.1007/s00394-016-1356-0) contains supplementary material, which is available to authorized users.

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.

Dietary carrot consumption and the risk of prostate cancer

PURPOSE

Previous studies regarding the association between carrot intake and prostate cancer risk have reported inconsistent results. We conducted a meta-analysis to summarize evidence on this association and to quantify the potential dose-response relationship.

METHOD

A systematic literature search of papers published in August 2013 was conducted using PubMed, EMBASE, Scopus, Web of Science, the Cochrane register, and the Chinese National Knowledge Infrastructure databases, and the references of the retrieved articles were screened. The summary risk estimates with 95% confidence intervals (CIs) for the highest versus the lowest intake of carrots were calculated. A dose-response meta-analysis was also conducted for the studies reporting categorical risk estimates for a series of exposure levels.

RESULTS

We found a significantly decreased risk of prostate cancer associated with the intake of carrots (odds ratio 0.82, 95% CI 0.70-0.97). In addition, the dose-response meta-analysis indicated that for each serving per week, or 10 g per day increment of carrot intake, the risk estimate of prostate cancer was 0.95 (0.90-0.99) or 0.96 (0.94-0.99). There was no evidence of significant publication bias based on Begg's funnel plot (P = 1.000) or Egger's test (P = 0.804).

CONCLUSION

Carrot intake might be inversely associated with prostate cancer risk. Because of the limited number of cohort studies and substantial heterogeneity observed between studies in this meta-analysis, further well-designed prospective studies are warranted to confirm the findings from our study.

Correlation of cancer incidence with diet, smoking and socio- economic position across 22 districts of Tehran in 2008

BACKGROUND

Variation in cancer incidence in geographical locations is due to different lifestyles and risk factors. Diet and socio-economic position (SEP) have been identified as important for the etiology of cancer but patterns are changing and inconsistent. The aim of this study was to investigate correlations of the incidence of common cancers with food groups, total energy, smoking, and SEP.

MATERIALS AND METHODS

In an ecological study, disaggregated cancer data through the National Cancer Registry in Iran (2008) and dietary intake, smoking habits and SEP obtained through a population based survey within the Urban Health Equity Assessment (Urban-HEART) project were correlated across 22 districts of Tehran.

RESULTS

Consumption of fruit, meat and dairy products adjusted for energy were positively correlated with bladder, colorectal, prostate and breast and total cancers in men and women, while these cancers were adversely correlated with bread and fat intake. Also prostate, breast, colorectal, bladder and ovarian cancers had a positive correlation with SEP; there was no correlation between SEP and skin cancer in both genders and stomach cancer in men.

CONCLUSIONS

The incidence of cancer was higher in some regions of Tehran which appeared to be mainly determined by SEP rather than dietary intake. Further individual data are required to investigate reasons of cancer clustering.

Egg consumption and risk of bladder cancer: a meta-analysis

The findings of epidemiologic studies on the association between egg consumption and bladder cancer risk remain conflicting. We conducted a meta-analysis to clarify the potential association between egg consumption and bladder cancer risk. Four cohort studies and 9 case-control studies in the PubMed database through February 2012 were identified on egg consumption and risk of bladder cancer involving 2715 cases and 184,727 participants. Random-effects models were used to calculate the summary relative risk estimates (SRRE) based on the highest compared with the lowest category of egg consumption. In addition, we performed stratified analyses and sensitivity and dose-response analyses to examine the association. Overall, no significant association was observed between egg consumption and bladder cancer (SRRE = 1.11 95% CI: 0.90-1.35). However, increased risk of bladder cancer was detected in North/South America (SRRE = 1.40 95% CI: 1.05-1.86) and, moreover, fried egg intake positively associated with bladder cancer as well (SRRE = 2.04, 95% CI: 1.41-2.95). In conclusion, our findings suggest no significant association between egg consumption and bladder cancer risk, except for a possible positive relationship with the intake of fried eggs based on the limited number of studies. Additional studies, especially large prospective cohort studies, are warranted to confirm these findings.

Case-control study of diet in patients with cervical cancer or precancerosis in Wufeng, a high incidence region in China

PURPOSE

To investigate the diet of patients with cervical cancer and precancerosis in the Wufeng area, a high- incidence region in China.

METHODS

In the case group, 104 patients diagnosed with cervical cancer or cervical intraepithelial neoplasias (CINII/III) were recruited from the Wufeng area. Nine hundred thirty-six healthy women were selected from the same area as the matched controls. A questionnaire, which included questions about general lifestyle conditions, smoking and alcohol status, source of drinking water, green tea intake, and diet in the past year, was presented to all participants.

RESULTS

Green tea intake (P=0.022, OR=0.551, 95% CI=0.330-0.919) and vegetable intake (P=0.035, OR=0.896, 95% CI=0.809-0.993) were identified as protective factors against cervical cancer or CINII/III. There was no indication of any associations of other lifestyle factors (smoking status, alcohol status, source of drinking water) or diet (intake of fruit, meat/egg/milk, soybean food, onion/garlic, staple food and pickled food) with cervical cancer.

CONCLUSIONS

The results suggest that eating more fresh vegetables and drinking more green tea may help to reduce the risk of cervical cancer or CINII/III in people of the Wufeng area.

Egg intake and bladder cancer risk: A meta-analysis

Egg intake has been hypothesized to promote carcinogenesis due to its potential to increase circulating levels of cholesterol. Epidemiological findings regarding the association between egg consumption and risk of bladder cancer have been inconsistent. We performed a meta-analysis of the available data. Relevant studies were identified by a PubMed database search of articles dating from between January 1980 and December 2011. We identified 4 cohort and 9 case-control studies of egg intake and risk of bladder cancer. Both fixed- and random-effects models were used to calculate the summary risk estimates (REs). The combined RE of bladder cancer for the highest compared with the lowest egg intake was 0.94 (95% CI, 0.69–1.18) and weak evidence of heterogeneity was observed. The association between egg intake and risk of bladder cancer differed significantly by geographic region, with a 28% reduced risk in Japanese. Our results provided no strong evidence of a significant association of egg consumption with bladder cancer incidence but showed a protective effect in Japanese.

Intake of red meat and heterocyclic amines, metabolic pathway genes and bladder cancer risk

We analyzed the association between meat intake, heterocyclic amines (HCAs) and bladder cancer (BC) risk in a large case-control study comprised of 884 BC cases and 878 healthy controls, recruited from 1999 to 2009. Epidemiologic and dietary data were collected via an in-person interview. Compared to the lowest quartile of red meat intake, the odds ratios (ORs) for the second, third and fourth quartiles were 1.17 (95% CI: 0.87-1.58), 1.47 (95% CI: 1.09-1.99) and 1.95 (95% CI: 1.41-2.68), respectively, (p-for trend <0.001). In a subset of participants with intakes of HCAs available, compared with those with the lowest quartile of intake, the ORs for the second, third and fourth quartiles were 1.47 (95% CI: 0.60-3.64), 2.58 (95% CI: 1.09-6.11) and 3.32 (95% CI: 1.37-8.01), respectively, (p for trend <0.001). In cumulative analysis of SNPs in the pathway, compared with subjects carrying 0-4 unfavorable genotypes, subjects carrying 5 and 6 or more unfavorable genotypes were at 1.60-fold (95% CI: 1.20-2.12) and 2.37-fold (95% CI: 1.82-3.10) increased risk, respectively. Moreover, subjects carrying six or more unfavorable genotypes and whose red meat intake was in the highest quartile were at 5.09-fold increased risk (95% CI: 2.89-8.96; p < 0.001). These results strongly support that high red meat intake, high intake of HCAs and carrying high number of unfavorable genotypes in the HCA metabolic pathways are associated with increased risk of BC in the study population.

Pathobiology and chemoprevention of bladder cancer

Our understanding of the pathogenesis of bladder cancer has improved considerably over the past decade. Translating these novel pathobiological discoveries into therapies, prevention, or strategies to manage patients who are suspected to have or who have been diagnosed with bladder cancer is the ultimate goal. In particular, the chemoprevention of bladder cancer development is important, since urothelial cancer frequently recurs, even if the primary cancer is completely removed. The numerous alterations of both oncogenes and tumor suppressor genes that have been implicated in bladder carcinogenesis represent novel targets for therapy and prevention. In addition, knowledge about these genetic alterations will help provide a better understanding of the biological significance of preneoplastic lesions of bladder cancer. Animal models for investigating bladder cancer development and prevention can also be developed based on these alterations. This paper summarizes the results of recent preclinical and clinical chemoprevention studies and discusses screening for bladder cancer.

Intake of α-linolenic acid and other fatty acids in relation to the risk of bladder cancer: results from the New Hampshire case-control study

The role of dietary fat in bladder cancer aetiology is currently unclear due to few studies, equivocal findings and a lack of information on important dietary fatty acids. The aim of the present study was to investigate the association between the intake of major dietary fats and fatty acids and the risk of bladder cancer. A case-control study was conducted in New Hampshire, USA. Dietary data were collected from 322 cases and 239 controls, and OR and 95 % CI were calculated using unconditional logistic regression. Adjustment was made for potential confounders: sex, age, smoking status, pack-years smoked, cholesterol and energy intake. Statistically significant reduced odds of bladder cancer were observed for high intakes (highest quartile v. lowest quartile) of α-linolenic acid (ALA) (OR 0·26, 95 % CI 0·10, 0·65; P for trend = 0·01) and vegetable fat (OR 0·39, 95 % CI 0·18, 0·86; P for trend = 0·03). Borderline statistically significant reduced odds were detected for polyunsaturated fat (OR 0·43, 95 % CI 0·19, 0·98; P for trend = 0·07) and linoleic acid (OR 0·43, 95 % CI 0·19, 0·96; P for trend = 0·06). These fats and fatty acids were highly correlated and following adjustment for each other, the only potential inverse association to remain was for ALA. The present findings suggest that ALA may have a protective role against developing bladder cancer; however, further investigation and replication in other epidemiological studies are required. Future research should focus on the type, source and quantities of different dietary fatty acids consumed.

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.

Risk factors for bladder cancer

AIMS AND BACKGROUND

To summarize risk factors for bladder cancer, emphasizing the role of recently established associations and to present some ongoing debates on the issue.

METHODS

A systematic literature search was performed using MEDLINE database on bladder cancer risk factors between January 1985 and June 2006 and by detailed examination of the references of original articles, reviews and monographs retrieved.

RESULTS

Cigarette smoking is recognized as the main cause of bladder cancer and accounts for about 50% of cases in developed countries. A strong link exists between the amount and duration of cigarette smoking. A high risk of bladder carcinoma has been observed in workers exposed to some aromatic amines. Based on these and other occupational risks, it has been estimated that 5-10% of bladder carcinomas in industrialized countries were due to exposures of occupational origin. Infectious agents have a major influence on bladder cancer risks in the areas of the world where Schistosoma haematobium infestation is endemic. Other potential risk factors for bladder cancer are other urinary tract infections and drinking tap water with chlorination by-products or arsenic. Exposure to certain drugs, like cyclophosphamide used in chemotherapy and heavy consumption of phenacetin-containing analgesics, has been shown to cause bladder cancer in humans. Total fluid intake and high consumption of fruits and vegetables are probably associated with a small decrease in risk.

CONCLUSIONS

Avoidance of tobacco smoking and incriminated occupational exposures, habitual intake of fresh fruits and vegetables, and prevention and control of urinary tract infections should be recommended for bladder cancer prevention. Further studies are required to assess the role of genetic polymorphisms and their modifying effect of lifestyle risk factors for bladder cancer occurrence and to evaluate the benefit of bladder cancer screening, particularly in those at high risk.