Artificial sweeteners and cancer of the lower urinary tract

The Impact of Artificial Sweeteners on Human Health and Cancer Association: A Comprehensive Clinical Review

Artificial sweeteners are sugar substitutes that provide high sweetening power associated with low accompanied calories. In this study, we aim to review the data on the use, benefits, side effects, and cancer risks of artificial sweeteners. We reviewed data in the PubMed, MEDLINE, Google Scholar, Embase, and Scopus databases to search for studies about artificial sweeteners from the inception of the database to July 20, 2023, published in the English language. We discuss systematic reviews and meta-analyses, randomized clinical trials, and observational cohort studies that address the use of artificial sweeteners and their effect on health. In our review, we show that artificial sweeteners have been shown to impact various functions of the gastrointestinal system. Other studies have demonstrated an association with neurologic symptoms such as headache and taste alteration. Moreover, recent studies have established an association between artificial sweeteners and cardiovascular risk and diabetes. Importantly, the majority of research data show no link between the use of artificial sweeteners and cancer risk. Although most studies show that there is no established link between these products and cancer risk, artificial sweeteners are associated with multiple diseases. Hence, more studies are needed to better characterize the effect of artificial sweeteners on human health.

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.

A Study of Artificial Sweeteners and Thyroid Cancer Risk

Background

In recent decades, data from certain observational studies have stirred controversy over artificial sweeteners by linking them with certain malignancies. As the incidences of artificial sweetener consumption and thyroid cancer are both increasing, our study aimed to determine any possible association between them.

Methods

This retrospective observational study enrolled 50 patients (group 1) with proven diagnosis of well-differentiated thyroid cancer (WDTC) and 50 control subjects (group 2) diagnosed as having benign thyroid nodule by fine-needle aspiration. The survey questionnaire included the total amount and duration of intake of artificial sweeteners.

Results

Increased consumption of artificial sweeteners was noted in group 1 as compared to group 2, which was statistically significant (76% vs. 24%, P < 0.01). This study suggested that the use of an average of four packets (4 g) per day of artificial sweetener for an average duration of 5 years is associated with WDTC.

Conclusions

Our study emphasizes the significance of artificial sweetener consumption as a potential risk factor for WDTC and increase in public awareness regarding this association if other studies in future report similar findings.

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.

Epidemiology of urinary bladder cancer: from tumor development to patient’s death

Urinary bladder cancer (UBC) ranks ninth in worldwide cancer incidence. It is more frequent in men than in women. We review the main established/proposed factors, both environmental and genetic, associated with bladder cancer etiology and prognosis. Data were extracted from previous reviews and original articles identified from PubMed searches, reference lists, and book chapters dealing with the reviewed topics. Evaluation and consensus of both the contribution of each factor in bladder cancer burden and the appropriateness of the available evidences was done during an ad hoc meeting held during the 18th Congress of the European Society for Urological Research. Cigarette smoking and specific occupational exposures are the main known causes of UBC. Phenacetin, chlornaphazine and cyclophosphamide also increase the risk of bladder cancer. Chronic infection by Schistosoma haematobium is a cause of squamous cell carcinoma of the bladder. NAT2 slow acetylator and GSTM1 null genotypes are associated with an increased risk of this cancer. Vegetables and fresh fruits protect against this tumor. Regarding prognosis, there is little knowledge on the predictive role of environmental exposures and genetic polymorphisms on tumor recurrence and progression and patient's death. Although active tobacco smoking is the most commonly studied factor, no definitive conclusion can be drawn from the literature. More research is needed regarding the effect of complex etiological factors in bladder carcinogenesis. Subgroup analysis according to stage, grade, and molecular features may help in identifying specific etiological and prognostic factors involved in different bladder cancer progression pathways.

Superficial bladder cancer: part 1. Update on etiology, classification and natural history

Superficial 'nonmuscle-invasive' bladder tumors represent a heterogeneous group of cancers, which include those that are papillary in nature and limited to the mucosa (Ta), high grade, flat and confined to the epithelium (Tis) and those that invade the submucosa or lamina propria (T1). The natural history of these bladder cancers is that of disease recurrence and progression to higher grade and stage. Furthermore, recurrence and progression rates of superficial bladder cancer vary according to several tumor characteristics. The goal in the treatment of superficial bladder cancer is twofold: reducing tumor recurrence and the subsequent need for additional therapies, such as cystoscopy, transurethral resections, intravesical therapy and the morbidity associated with these treatments; and preventing tumor progression and the subsequent need for more aggressive therapy, such as radical cystectomy. The administration of intravesical chemotherapy and immunotherapy has become an important component in accomplishing these goals. This update is the first part of two articles reviewing important contemporary concepts in the etiology, classification and natural history of superficial bladder cancer, while part II of the series will review and highlight important aspects in management of superficial bladder cancer.

Artificial sweeteners and cancer risk in a network of case–control studies

BACKGROUND

The role of sweeteners on cancer risk has been widely debated over the last few decades. To provide additional information on saccharin and other sweeteners (mainly aspartame), we considered data from a large network of case-control studies.

METHODS

An integrated network of case-control studies has been conducted between 1991 and 2004 in Italy. Cases were 598 patients with incident, histologically confirmed cancers of the oral cavity and pharynx, 304 of the oesophagus, 1225 of the colon, 728 of the rectum, 460 of the larynx, 2569 of the breast, 1031 of the ovary, 1294 of the prostate and 767 of the kidney (renal cell carcinoma). Controls were 7028 patients (3301 men and 3727 women) admitted to the same hospitals as cases for acute, non-neoplastic disorders. Odds ratios (ORs), and the corresponding 95% confidence intervals (CIs), were derived by unconditional logistic regression models.

RESULTS

The ORs for consumption of saccharin were 0.83 (95% CI 0.30-2.29) for cancers of the oral cavity and pharynx, 1.58 (95% CI 0.59-4.25) for oesophageal, 0.95 (95% CI 0.67-1.35) for colon, 0.93 (95% CI 0.60-1.45) for rectal, 1.55 (95% CI 0.76-3.16) for laryngeal, 1.01 (95% CI 0.77-1.33) for breast, 0.46 (95% CI 0.29-0.74) for ovarian, 0.91 (95% CI 0.59-1.40) for prostate and 0.79 (95% CI 0.49-1.28) for kidney cancer. The ORs for consumption of other sweeteners, mainly aspartame, were 0.77 (95% CI 0.39-1.53) for cancers of the oral cavity and pharynx, 0.77 (95% CI 0.34-1.75) for oesophageal, 0.90 (95% CI 0.70-1.16) for colon, 0.71 (95% CI 0.50-1.02) for rectal, 1.62 (95% CI 0.84-3.14) for laryngeal, 0.80 (95% CI 0.65-0.97) for breast, 0.75 (95% CI 0.56-1.00) for ovarian, 1.23 (95% CI 0.86-1.76) for prostate and 1.03 (95% CI 0.73-1.46) for kidney cancer. A significant inverse trend in risk for increasing categories of total sweeteners was found for breast and ovarian cancer, and a direct one for laryngeal cancer.

CONCLUSION

The present work indicates a lack of association between saccharin, aspartame and other sweeteners and the risk of several common neoplasms.

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.

Lifestyle issues and genitourinary tumours

A variety of lifestyle factors, including physical activity, artificial sweeteners, alcohol consumption and smoking, have been reported to contribute to the risk of developing urological malignancies. A great number of epidemiological studies suggest that sports and physical activity may have a preventive influence on genitourinary tumours, especially on the incidence of prostate cancer. Smoking appears to be the most relevant lifestyle factor significantly increasing both incidence and mortality from bladder cancer. Furthermore, there is evidence implicating an association between tobacco use and kidney cancer. In contrast, prostate and testicular cancers are unlikely to be linked to tobacco use. As far as alcohol is concerned, most studies indicate that neither amount nor type of alcohol seems to be clearly associated with a risk of developing urological malignancies. However, some more recent cohort studies suggest a moderately increased risk for prostate and bladder cancer for specific types of alcohol. On the other hand, there is evidence that moderate alcohol consumption may even protect women from developing renal cancer. Since the introduction of artificial sweeteners, reports of potential cancer risks have circulated periodically through the mass media. The wide distribution of these agents and the fact that mostly combinations of the different compounds are added to a broad variety of food, drinks, drugs, and hygiene products complicates a systematic analysis of their potential impact on the development of urological malignancies. Nevertheless, so far not a single study has convincingly demonstrated a statistically significant risk of bladder cancer due to the consumption of artificial sweeteners. This survey demonstrates that the individual assessment of lifestyle factors not only may identify groups with an increased risk for urological malignancies but also clearly displays a potential for tumour prevention.

Saccharin mechanistic data and risk assessment: urine composition, enhanced cell proliferation, and tumor promotion

Sodium saccharin (NaSac) produces bladder tumors consistently in male rats only after lifetime exposure that begins at birth. NaSac is not metabolized and is negative in most genotoxicity tests. NaSac-induced cell damage and proliferation have been proposed as important factors in tumor promotion, and dose-response information demonstrating a threshold for these parameters is available. One theory proposes that high levels of NaSac, combined with protein in a high Na+, high pH environment found only in the male rat, form toxic microscopic crystals; therefore, NaSac-induced tumors may not be relevant to human carcinogenesis.

Relative importance of risk factors in bladder carcinogenesis: some new results about Mediterranean habits

In the Mediterranean region of France where bladder cancer mortality and incidence are high, a case-control study with 219 male incident cases and 794 randomized, male population-controls was carried out in 1987-89 to investigate bladder cancer risk factors and more specifically, regional factors. A stepwise logistic regression was applied to the data. This investigation confirms the role of tobacco and of certain occupational exposures in bladder carcinogenesis. There was a significant dose-response relationship with lifelong coffee drinking and alcohol consumption; however the risk estimates were only significantly elevated for the heaviest drinkers. The intake of saccharin was not associated with risk of bladder cancer. Infrequent consumption of carrots, spinach, and marrows conferred an increased risk, suggesting a protective effect of vitamin A. Finally, this investigation results in some new hypotheses. The study of residences and birthplaces has revealed a lower risk for those who have lived in a non-Mediterranean area and a higher risk for those born in a Mediterranean area. These features might be explained by some Mediterranean dietary habits, such as a high consumption of spices (odds ratio = 3.64, 95 percent confidence interval = 2.21-5.98).

Bladder cancer and coffee drinking: a summary of case-control research

An association between coffee drinking and cancer of the lower urinary tract (LUT) was first suggested 20 years ago and has been the subject of many epidemiological studies. We have undertaken a critical review and statistical summary of 35 case-control studies of this association published between 1971 and 1992. Predefined methodological criteria were applied to the available reports. Studies were classified as either meeting the criteria (core studies) or failing to satisfy at least one of the requirements for design or analysis (non-core studies). The summarised data from the 8 core studies showed no evidence of an increase in risk of LUT cancer with coffee drinking in men or women after adjustment for the effects of cigarette smoking (odds ratio 1.07 [95% CI 1.00-1.14] for men, 0.91 [0.81-1.03] for women). The measures of association from the non-core studies were higher on average than those from the core studies, although the inclusion of these data in an overall summarised estimate did not substantially change the findings from the core analysis. We conclude that the best available data do not suggest a clinically important association between the regular use of coffee and development of cancer of the LUT in men or women.

Assessment of the carcinogenicity of the nonnutritive sweetener cyclamate

The weight of the evidence from metabolic studies, short-term tests, animal bioassays, and epidemiological studies indicates that cyclamate (CHS) is not carcinogenic by itself; however, there is evidence from in vitro and in vivo studies in animals that implies it may have cancer-promoting or cocarcinogenic activity. Epidemiological studies indicate that the use of nonnutritive sweeteners (CHS and saccharin) has not resulted in a measurable overall increase in the risk of bladder cancer in individuals who have ever used these products. No epidemiological information exists on the possible associations of these sweeteners and cancers other than those of the urinary tract. It is recommended that (1) no further studies on the metabolism of CHS to evaluate its carcinogenicity are required since no potentially hazardous metabolites have been appreciably detected in humans; (2) no further animal bioassays to test for the carcinogenicity of CHS by itself are necessary; (3) the studies in rodents that suggest a promotional or cocarcinogenic effect of CHS should be repeated because they cannot be ruled out; (4) because the significance to human health of a positive outcome of such studies is uncertain, additional research aimed at understanding the predictive value for human health of such results and more generic studies to develop well-validated systems that can be relied on in the assessment of cancer-promoting agents are recommended; (5) in populations where CHS continues to be used, epidemiological monitoring should be continued to determine whether there is an increased risk of cancer in humans who are heavy or long-term users or for those observed long after first exposure. In such monitoring, other cancer sites--in addition to the bladder--should be considered.

Sugar and fat substitutes: the challenge for today and tomorrow

Companies have contributed greatly to meeting the challenge of providing a variety of reduced calorie ingredients allowing food manufacturers to choose the most appropriate ingredient to prepare the tastiest product. These sugar and fat substitutes alone do not lead to healthier eating. The diabetes educator needs to teach clients who wish to lose weight, or to reduce sugar or fat intake, to select foods made with sugar or fat substitutes (when available) as part of a balanced meal plan that meets their nutritional requirements. These products can be a factor in achieving the balance of diet and exercise essential to a healthy life-style.

Environmentally related diseases of the urinary tract

Nephrotoxicity from exposure to therapeutic agents and chemicals in the environment and workplace results in a broad spectrum of clinical renal disease that may mimic disorders from other causes. Nephrotoxic agents may, in fact, be responsible for some fraction of renal disease of undetermined etiology. Specific diagnosis and treatment by removal from exposure to the toxic agent is more likely in the early phase of the disorder. Measurement and characterization of proteinuria provides the most sensitive and reliable method of early detection. Increased urinary excretion of serum proteins with molecular weight in excess of 50,000, such as albumin and transferrin, is an early indicator of glomerular injury. Low-molecular-weight proteinuria (beta 2-microglobulin or retinol-binding protein) and enzymuria, particularly excretion of NAG, are sensitive indicators of renal tubular cell injury. Tests that reflect hypersensitivity reactions are often indicative of immunologically mediated nephrotoxicity but are not specific for the kidney. Cancers of the kidney and urinary bladder appear to be increasing and are most common among the socially active and affluent. Susceptibility of the urinary tract to toxicity and carcinogenicity reflect contact of excreted toxins with the epithelial cells of nephrons and urinary bladder.

Histologic changes in the urinary bladder in relation to cigarette smoking and use of artificial sweeteners

A total of 6503 sections of urinary bladder epithelium from 282 subjects were examined in random order, and histologic alterations, particularly the number of cell rows and the presence and extent of cells with atypical nuclei, were recorded. Cases were either individuals who had never smoked or who had smoked cigarettes. Microscopic slides with cells having 50% or more atypical nuclei were found in 4.3% of those who had never smoked; 67.1% in those who had smoked less than 20 cigarettes a day; 82.3% in those who had smoked 20 to 39 cigarettes a day; and 88.4% of the 40 or more a day cigarette smokers. The percentage of slides with six or more cell rows in these groups were 4.8%, 52.2%, 62.5%, and 72.9%, respectively. The histologic findings in the urinary bladder in relation to smoking habits fully complement the epidemiologic studies showing a dose-response of cigarette smoking and urinary bladder cancer. No relationship was found between changes in the urinary bladder epithelium and the use of artificial sweeteners.

Sugar and sugar substitutes. Comparisons and indications

Public confusion and concern about the use of sugar and sugar substitutes are widespread. Physicians must be prepared to answer patients' inquiries about these substances. Some population groups should avoid certain sugar substitutes. In particular, pregnant women and young children should avoid saccharin, and phenylketonuric homozygous persons should avoid aspartame. In a varied, balanced diet, the use of aspartame and saccharin is one safe way for the general population to enjoy sweet foods with fewer calories and less cariogenic potential. Sugar substitutes may be helpful in dietary compliance for overweight and diabetic patients.

Tobacco and occupation as risk factors in bladder cancer: a case-control study in southern Belgium

A pilot case-control study on bladder cancer, with population-based controls matched for each of 74 cases, has been conducted in two industrial areas of Southern Belgium in order to analyze the influence of tobacco use and occupation. Observed bladder cancer risk for smokers is more than 5 times higher than that for non-smokers, and the risk for people having an a priori hazardous occupation is about 3.5 times higher than that of other subjects. A dose-response relationship was found for tobacco exposure and duration of employment. It seems that the risk is increased in a log-linear way by these variables. Population attributable risks show that in 20 cases of bladder cancer, 17 could be explained by the two factors combined. This study also reveals an increased risk for metal workers, truck and engine drivers, coal-miners, and rubber and coal-tar workers. The risk for metal workers is specially high in the case of turners, metal fitters, blacksmiths, stokers and workers exposed to hot metal.

Workshop on guidelines to the epidemiology of weak associations. Confounding

The magnitude of confounding is examined in nine case studies of two "weak" relationships: between artificial sweeteners and bladder cancer, and between oral contraceptives and cervical dysplasia. Confounding had little or no influence on the results of any published study. The responsible epidemiologist must always consider the possibility of confounding, no less when associations are weak than when they are strong. Identification of potentially confounding variables is an integral part of good epidemiologic practice. Rarely, however, does confounding itself, especially from unidentified sources, live up to its reputation for introducing seriously spurious associations. An investigator is more likely to be led astray by undetected biases than by pure confounding.

In utero-exposure to saccharin: a threat?

In-utero or immediate post-utero exposure of rats to saccharin results in an increased incidence of bladder tumors when compared to post-weaning exposure only. We studied 6 human mother-infant pairs following maternal intake of saccharin close to delivery. High performance liquid chromatography revealed the presence of saccharin in all 6 newborn cord sera as well as their mothers' sera and urine. This constitutes the first report of placental transfer of saccharin in humans. Despite the relative weakness in carcinogenicity of saccharin, this in-utero exposure, coupled with ex-utero exposure, may possibly contribute to an increased incidence of neoplasms.

Artificial sweetener use and one-year weight change among women

Weight change over a 1-year period was examined in a highly homogeneous group of 78,694 women ages 50-69 enrolled in a prospective mortality study. Artificial sweetener usage increased with relative weight and decreased with age. Users were significantly more likely than nonusers to gain weight, regardless of initial weight. Average weight gains or losses by artificial sweetener users differed by less than 2 pounds from gains or losses among nonusers. These results were not explicable by differences in food consumption patterns. The data do not support the hypothesis that long-term artificial sweetener use either helps weight loss or prevents weight gain.

Bladder cancer in nonsmokers

Potential risk factors for bladder cancer were studied in a series of 76 male and 76 female bladder cancer cases and 238 male and 254 female controls who reported never having smoked. Risk factors included usual occupation, smoking by the spouse, sidestream smoke exposure at home and at work and in transportation, coffee drinking (caffeinated and decaffeinated), artificial sweetener use, body mass index, and a history of diabetes and high blood pressure. No association was found with spouse's smoking or reported sidestream smoke exposure, coffee drinking, artificial sweetener use, or a number of other variables; however, there was some indication that several occupations were overrepresented in the cases. A positive association was found with snuff use in women, but the numbers were small (three cases and one control). Restriction of the study to lifetime nonsmokers permitted the assessment of potential risk factors in the absence of potential confounding and interactive effects of smoking. The study had adequate statistical power to detect moderately small elevated risks due to the main factors examined.

Toxicological aspects of cyclamate and cyclohexylamine

In the late 1960s the artificial sweetener cyclamate was implicated as a bladder carcinogen in rats. This finding and other concerns about its safety ultimately led to a ban on cyclamate in the U.S. and restrictions on its use in many other countries. Since that time, the carcinogenic potential of cyclamate and cyclohexylamine, its principal metabolite, has been reevaluated in a group of well-controlled, well-designed bioassays that have failed to substantiate the earlier findings. This review of the published and unpublished literature on cyclamate attempts to evaluate the carcinogenicity question and other important aspects of the toxicity of cyclamate and cyclohexylamine, including their effects on various organ systems, their genotoxic potential, and their effects on reproduction. In addition, the physiological disposition of cyclamate is reviewed, with particular attention directed toward the site and extent of its conversion to cyclohexylamine.

Occupation and bladder cancer in Boston, USA, Manchester, UK, and Nagoya, Japan

Relations between occupational history and the development of cancer of the lower urinary tract ("bladder cancer") were evaluated in Boston, Massachusetts, USA, Manchester, UK, and Nagoya, Japan. Population-based series of incident cases and controls were identified and interviewed in each area. The present analysis was limited to men and was based on 430 cases and 397 controls in Boston, 399 cases and 493 controls in Manchester, and 226 cases and 443 controls in Nagoya. In Boston, elevated risk of bladder cancer was associated with employment related to dyes (relative risk = 2 X 1; 90% confidence interval, 0 X 9-5 X 1), leather (1 X 7; 1 X 1-2 X 6), paint (1 X 5; 0 X 9-2 X 4), or organic chemicals (1 X 6; 1 X 1-2 X 5). In Manchester, elevated risk was associated with 0 X 9-3 X 6). No clear association was observed between occupation and risk in Nagoya. Elevations in risk related to occupation generally were stronger in men under 65 years of age compared to older men. Differences from place to place in associations between occupation and risk may be the result of differences in the exposures to hazardous agents that jobs with the same title involve.

Bladder cancer risk among auto and truck mechanics and chemically related occupations

Male participants in the NCI National Bladder Cancer study were evaluated for risks in auto and truck mechanic and in chemically related exposure occupations compared with those who had never worked in these areas. In nonsmokers the adjusted rate ratios (RR) for mechanics equalled 1.33, (95% CI 0.77, 2.31). The adjusted RR in the nonsmoker chemically related group was 1.53 (95% CI 1.13, 2.07). Duration of exposure as a mechanic was not clearly associated with bladder cancer risk regardless of smoking status.

Causes of death among female chemists

A mortality odds ratio analysis of cause of death among 347 White female members of the American Chemical Society (ACS) revealed a five-fold excess of suicide, notably by cyanide poisoning. Risk was also elevated for all cancers combined and for cancers of the breast, ovary, stomach, pancreas, and lymphatic and hematopoietic system. The excess breast and ovary cancer deaths were limited to unmarried women.

The effect of saccharin on the microbial metabolism of tryptophan in man

The microbial catabolism of tryptophan to indole has been studied in 15 human subjects by analysis of the daily urinary excretion of indican (potassium indoxylsulphate) before, during and after chronic saccharin ingestion. The daily excretion of indican during a 3-wk control period showed marked inter- and intra-subject variability. Analysis of the urinary excretion of saccharin during chronic administration demonstrated good compliance for both saccharin ingestion and urine collection. The urinary excretion of indican was not increased significantly by the ingestion of saccharin (1 g/day as divided doses with meals) for one month. These findings are consistent with epidemiology studies which show the absence of a consistent excess risk of cancer of the urinary bladder in humans ingesting saccharin as a food additive.

A review of epidemiological studies on artificial sweeteners and bladder cancer

Next to tobacco, saccharin may be the substance that has been most studied epidemiologically. Over 5000 patients with bladder cancer have participated in case-control studies; over 27,000 diabetics have been observed for 234,000 person-years. The summary relative risk from combining all case-control studies is less than 0.98, the standardized mortality ratio for bladder cancer in diabetics is only 70. Analysis of these studies leads to the conclusion that saccharin is not related to human bladder cancer.

Bladder cancer in the aluminium industry

The incidence of bladder cancer is unusually high in aluminium smelter workers. An epidemiological study showed that workers in Soderberg potrooms are at highest risk for bladder cancer, the adjusted overall relative risk being 2.39 (1.34-4.28). Exposure to polycyclic aromatic hydrocarbons, of which benz(a)pyrene (BaP) served as an indicator, seems to be the causative factor. The relative risk was evaluated at 12.38 for workers with 20 or more equivalent years of BaP exposure. Cigarette smoking contributed significantly to the appearance of bladder cancer in the population studied. There is a synergistic effect when cigarette smoking and BaP exposure are combined; the numbers in our population are too small to determine whether this interaction effect is multiplicative or additive. It is concluded that bladder cancer is associated with aluminium smelting (primarily with the Soderberg process).

An international study of smoking and bladder cancer

The effects of smoking cigarettes and other forms of tobacco on the development of cancer of the lower urinary tract (bladder cancer) were evaluated in Boston, Massachusetts, Manchester, United Kingdom and Nagoya, Japan. Population-based series of incident cases and controls were identified and interviewed in each area. The present analyses were based on 592 cases and 533 controls in Boston, 553 cases and 731 controls in Manchester, and 290 cases and 588 controls in Nagoya. Smokers of cigarettes had about twice the incidence of bladder cancer as nonsmokers. In men the strength of the association between cigarette smoking and bladder cancer was similar in the 3 study areas. The strength of the association varied somewhat from area to area among women. Bladder cancer risk increased with frequency of cigarette smoking and with deep inhaling. In Boston men who smoked 2 or more packs of cigarettes per day and inhaled deeply had nearly 7 times the risk of nonsmokers. Ex-smokers had a level of risk between that of current smokers and nonsmokers. However, there was no clear relationship between risk and age at which cigarette smoking began, time since discontinuation among ex-smokers and use of filters. Over-all, there was little difference in bladder cancer risk between men who had and who had not smoked pipes but pipe smoking did appear to be associated with risk among men who had never smoked cigarettes. Cigar smoking was unrelated to bladder cancer.

Artificial sweeteners and absence of bladder cancer risk in Copenhagen

During the years 1979 to 1981 a population-based case-control study of bladder cancer including papillomas was performed in Greater Copenhagen. After exclusions some 388 patients (290 males; 98 females) and an age- and sex-matched group of 787 controls (592 males; 195 females) remained for analysis. Controls were selected at random from the general population of the study area. All persons were interviewed concerning use of artificial sweeteners in addition to their exposure to a number of other known or suspected risk factors for bladder cancer. Fifty-five male bladder cancer patients (19.4%) and 150 controls (25.7%) had at some time used artificial sweeteners regularly. Among females 27.1% of cases and 25.9% of controls regularly used sweeteners. In neither sex was the relative risk significantly increased in users compared with non-users of artificial sweeteners. The relative risk of 0.78 in the two sexes combined was not significantly different from 1.0 (95% C.I.: 0.58-1.05). There was no indication of a regular increase in risk with increasing daily consumption of table-top sweeteners nor was there any indication of an increase in risk with a duration of regular use of artificial sweeteners. Taking into account a possible latency period between first regular use and bladder cancer development did not change the finding of an absence of association between use of artificial sweeteners and the risk of bladder cancer. Neither saccharine nor cyclamate users had an increased risk of bladder cancer. This population-based case-control investigation provides further evidence that it is highly unlikely that the consumption of artificial sweeteners has contributed to current bladder cancer rates in man.

Saccharin: a toxicological and historical perspective

Saccharin, first synthesized in 1879, eventually became popular as an inexpensive substitute for sugar, particularly as a non-caloric sweetner. The dispute concerning the safety of saccharin for human consumption is almost as old as saccharin itself. In this article, the history concerning the uses of saccharin and the accompanying controversy are reviewed. In addition, the spectrum of toxicological and epidemiological studies to which saccharin has been subjected are also examined. While the toxicological data indicate that saccharin is probably the agent solely responsible for the bladder tumors observed in second generation male rats, the epidemiological studies provide, at best, an equivocal relationship between the consumption of saccharin and bladder cancer. A benefit-risk evaluation for saccharin showed few, if any documentable benefits from the use of saccharin and much genuine uncertainty concerning the potential risks for ingestion by man. This element of genuine uncertainty as to the extent of human risk posed to man is the crux of saccharin's past and its foreseeable future.

A case-control study of female bladder cancer

A case-control study was performed on 47 female bladder cancer patients and 94 female controls matched in age and geographic area. Twenty-five determinants of assumed importance were examined. The bivariate associations revealed a significantly increased relative risk (RR) for bladder cancer associated with use of tobacco, cheroot smoking and saccharin consumption, and some subgroups like never-smokers in combination with use of saccharin. The population attributable risk percentages were estimated. Through a multivariate logistic analysis of selected determinants cheroot consumption was the most pronounced independent variable.

Bladder cancer. Management of an increasingly common tumor

The incidence of bladder cancer is slowly rising, which may be due in part to the increasing use of chemicals in every phase of our modern society. Improvements in detection will, it is hoped, allow earlier diagnosis, at a stage when it is highly likely that the entire tumor can be removed. Intravesical chemotherapy reduces the number and frequency of subsequent tumors and may be able to control the neoplastic process sufficiently to prevent progression and the need for cystectomy and/or radiation therapy. Unfortunately, advances in management of superficial tumors have not been matched for invasive tumors. Despite improvements in preoperative and postoperative care, introduction of the linear accelerator, and use of chemotherapy, about 50% of patients with stage B, C, or D bladder cancer die of the disease. Most patients with invasive tumors do not come to the attention of a physician until the tumor has progressed to this stage. Thus, a major task is to identify those harboring bladder cancer earlier, when the disease can be successfully managed.

Histologic features of bladder cancer in Boston, USA, Manchester, UK, and Nagoya, Japan

Histologic characteristics of bladder cancer in Boston, USA, Manchester, UK, and Nagoya, Japan, were evaluated. In each of these areas broadly-based series of cases were assembled during a collaborative case-control study. The present analysis was based on 589 cases in Boston, 484 cases in Manchester, and 241 cases in Nagoya. A single pathologist reviewed a slide of the primary tumor without reference to identifying information or other data. The primary histologic type of nearly all tumors was transitional-cell, and there was little variation in the proportion of transitional-cell tumors among the study areas. Nor was there much variation in the distribution of histologic grade, the proportion of tumors showing submucosal invasion, or the proportion of tumors with a papillary surface. Age at diagnosis was strongly correlated with histologic grade. The proportion of grade III (most malignant) tumors was about twice as high among patients 80 years of age and over as among those aged less than 50. An apparent association between age and submucosal invasion was explained in large part by the relationships of histologic grade to submucosal invasion and to age. Other histologic features had only weak and inconsistent relations with age. None of the features evaluated showed consistent associations with history of cigarette-smoking or with sex.

Intra-uterine exposure to saccharin and risk of bladder cancer in man

Animal experiments show that rats fed saccharin are more likely to develop bladder tumours if they have been exposed to saccharin in utero through their mothers' food. The risk of bladder tumours in humans following in utero exposure to saccharin has not been evaluated previously. In Denmark the use of saccharin increased sharply during the second World War as a result of scarcity of sugar, and import and export figures indicate that saccharin consumption was on average 4-5 times higher during the war-time period than in the pre-war decade. The risk of bladder tumours at ages 20-34 was 1.0 (95% confidence interval 0.7-1.6) among men born in 1941-1945 compared with men born 1931-1940. Among women the risk was 0.3 (0.1-1.0). This study provides no evidence of an increased risk of human bladder cancer during the first 30-35 years of life associated with in utero saccharine exposure.