Comparative epidemiology of cancers of the United States and Japan

Evaluation of relationships among national colorectal cancer mortality rates, genetic lactase non-persistence status, and per capita yearly milk and milk product consumption

Colorectal cancer (CRC) is one of the leading causes of mortality in Western countries. Its putative pathogenesis revolves around genetic and environmental factors, particularly diet. One of the most studied dietary factors, dairy product intake, is still debated as a protective agent. The role of lactose as a candidate prebiotic (stimulating lactic acid bacteria) and its relation to genetic lactase non-persistence (LNP) status has not been evaluated. We undertook a review and analysis of national per capita dairy product consumption, national LNP prevalence, and national CRC mortality rates (CRCM) to determine whether relationships existed among these variables. Data on these three items were obtained from the available literature. A negative binomial regression model was used to compare national LNP status with national CRCM rates for three time periods. Pearson correlation was used to compare national per capita dairy food intake with national CRCM rates for the approximate midpoint time period of reviewed articles. We found that there was a significant positive correlation between per capita dairy food intake and CRCM rates. However, there was also a significant negative correlation between national LNP prevalence and CRCM rates. Population-based studies supported the suggestion that in both homogeneous high and homogeneous low prevalence LNP countries characterized by low and high dairy food intake respectively, dairy food consumption exerted a protective effect against CRC and CRCM rate. Because some population studies contradict the hypotheses that dairy food intake promotes CRC or that LNP status protects against CRC, we hypothesize that dairy food consumption may operate by two distinct mechanisms--one that operates at low doses in LNP subjects and another in high doses in non-LNP subjects.

Ernst Wynder: a remembrance

Ernst Wynder, founder and president of the American Health Foundation, was my employer, mentor, and colleague for nearly 25 years. This brief remembrance provides some experiences and perspectives that influenced my career as a cancer epidemiologist.

Influence of smoking charcoal filter tipped cigarettes on various biomarkers of exposure

Charcoal (CC) filters of cigarettes are known to significantly reduce a series of volatile constituents in mainstream smoke, including reactive alpha,beta-unsaturated aldehydes such as acrolein and crotonaldehyde. We performed a randomized, crossover, 2-wk brand-switching study with 39 smokers. Twenty of the subjects smoked cellulose acetate (CA) filter tipped cigarettes during wk 1 of the study; the remaining 19 subjects smoked CC filter tipped cigarettes during wk 1. In wk 2, the subjects switched to the corresponding brand with the other filter type, with similar smoking machine-derived tar and nicotine yields. Daily cigarette consumption, carbon monoxide in exhaled breath, salivary cotinine, and urinary nicotine equivalents (molar sum of nicotine plus five major metabolites) did not change significantly when switching to the cigarettes with the other filter type. Urinary excretion rates of 3-hydroxy-1-methylpropylmercapturic acid (metabolite of crotonaldehyde), monohydroxybutenylmercapturic acid (metabolite of 1,3-butadiene), and S-phenylmercapturic acid (metabolite of benzene) were significantly lower when smoking CC compared to CA filter tipped cigarettes. The reduction in amount of 3-hydroxypropylmercapturic acid (metabolite of acrolein) was of borderline significance. Other mercapturic acids and thioethers (the latter is a summary parameter that indicates the exposure to electrophilic compounds) were not or were only slightly reduced upon smoking CC filter tipped cigarettes. We conclude that smoking CC filter tipped cigarettes does not change the uptake of carbon monoxide and nicotine when compared to CA filter tipped cigarettes with similar tar and nicotine yields, but significantly reduces the exposure to toxicologically relevant smoke constituents such as acrolein, crotonaldehyde, 1,3-butadiene, and benzene.

Charcoal cigarette filters and lung cancer risk in Aichi Prefecture, Japan

The lung cancer mortality rate has been lower in Japan than in the United States for several decades. We hypothesized that this difference is due to the Japanese preference for cigarettes with charcoal-containing filters, which efficiently absorb selected gas phase components of mainstream smoke including the carcinogen 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone. We analyzed a subset of smokers (396 cases and 545 controls) from a case-control study of lung cancer conducted in Aichi Prefecture, Japan. The risk associated with charcoal filters (73% of all subjects) was evaluated after adjusting for age, sex, education and smoking dose. The odds ratio (OR) associated with charcoal compared with 'plain' cigarette filters was 1.2 (95% confidence intervals [CI] 0.9, 1.6). The histologic-specific risks were similar (e.g. OR = 1.3, 95% CI 0.9, 2.1 for adenocarcinoma). The OR was 1.7 (95% CI 1.1, 2.9) in smokers who switched from 'plain' to charcoal brands. The mean daily number of cigarettes smoked in subjects who switched from 'plain' to charcoal brands was 22.5 and 23.0, respectively. The findings from this study did not indicate that charcoal filters were associated with an attenuated risk of lung cancer. As the detection of a modest benefit or risk (e.g. 10-20%) that can have significant public health impact requires large samples, the findings should be confirmed or refuted in larger studies.

Genistein inhibits growth of estrogen-independent human breast cancer cells in culture but not in athymic mice

The studies presented were conducted to assess the effect of the soy isoflavone genistein on proliferation of estrogen-independent human breast cancer cells (MDA-MB-231) in vitro and in vivo. Genistein (20 mcmol/L) inhibited cell proliferation in vitro by approximately 50%. Cell cycle progression was blocked in G(2)/M with 40 and 80 mcmol/L genistein. To evaluate the effect of dietary genistein on tumor growth in vivo, genistein was fed to female athymic mice inoculated with MDA-MB-231 cells. After solid tumor masses had formed, mice were fed genistein at a dose (750 mcg/g AIN-93G diet), shown to produce a total plasma genistein concentration of approximately 1 mcmol/L. This dose of genistein did not significantly (P > 0.05) alter tumor growth. Studies were then conducted to assess the effect of dietary genistein on initial tumor development and growth. Genistein (750 mcg/g AIN-93G diet), fed 3 d before cells were inoculated into mice, did not significantly (P > 0.05) inhibit tumor formation or growth. The plasma concentration of genistein in mice fed this dose of dietary genistein (750 mcg/g AIN-93G diet) does not appear sufficient to inhibit tumor formation or growth. Dietary genistein at 750 mcg/g AIN-93G diet does not inhibit tumor formation or growth. Additional studies were conducted to determine the effect of dietary dosages ranging from 0 to 6000 mcg/g AIN-93G diet on plasma genistein concentration. Plasma genistein concentration increased in a dose-dependent manner up to 7 mcmol/L at 6000 mcg/g AIN-93G diet. These data suggest that although genistein inhibits cancer cell growth in vitro, it is unlikely that the plasma concentration required to inhibit cancer cell growth in vivo can be achieved from a dietary dosage of genistein.

Synergistic effects of thearubigin and genistein on human prostate tumor cell (PC-3) growth via cell cycle arrest

There is evidence that habitual consumption of green tea by Japanese men is correlated with a reduction in cancers, including prostate; soybean isoflavones are also associated with increased protection. The present study compared the anti-proliferative effect of black tea (Camellia sinensis) polyphenol, thearubigin (TR), alone or combined with the isoflavone genistein, on human prostate (PC-3) carcinoma cells. TR administered alone did not result in any alteration of cell growth. When combined with genistein, however, TR significantly inhibited cell growth and induced a G2/M phase cell cycle arrest in a dose dependent manner. These findings indicate the potential use of combined phytochemicals to provide protection against prostate cancer.

Increased incidence of proximal colon cancer in the elderly

To define the characteristics of colorectal cancer with regard to site distribution, age, and sex, due to the significantly increased incidence of colorectal cancer in Japan, we investigated 1,205 Japanese patients with colorectal cancer between 1975 and 1994. When we compared site distribution for age and sex in the entire 20-year period, tumors in the proximal colon were more frequent in elderly patients than in young ones (p < 0.05); this tendency was true only for females (p < 0.01), but not for males. The increased incidence of proximal colon cancer in elderly patients was also found in the second 10-year period (p < 0.05). Because elderly patients are characterized by an increasingly high incidence of proximal colon cancer in recent years, more concerted efforts for the early detection of proximal colon cancer, particularly in the elderly, are called for.

Phytic acid in health and disease

Phytic acid (PA), a major phosphorus storage compound of most seeds and cereal grains, contributes about 1 to 7% of their dry weight. It may account for more than 70% of the total kernel phosphorus. PA has the strong ability to chelate multivalent metal ions, especially zinc, calcium, and iron. The binding can result in very insoluble salts that are poorly absorbed from the gastrointestinal tract, which results in poor bioavailability (BV) of minerals. Alternatively, the ability of PA to chelate minerals has been reported to have some protective effects, such as decreasing iron-mediated colon cancer risk and lowering serum cholesterol and triglycerides in experimental animals. Data from human studies are still lacking. PA is also considered to be a natural antioxidant and is suggested to have potential functions of reducing lipid peroxidation and as a preservative in foods. Finally, certain inositol phosphates, which may be derived from PA, have been noted to have a function in second messenger transduction systems. The potential nutritional significance of PA is discussed in this review.

Epidemiology of and risk factors for pancreatic cancer

In the United States, incidence of and mortality from pancreatic cancer increased for several decades earlier in this century but have tended to level off in recent years. Rates increase with age and are higher in blacks than in whites and higher in males than in females. No consistent differences by socioeconomic status or by geographic location in the United States have been identified, although international variation and differences in migrants have been observed. Thus, both genetic and environmental factors may be playing significant roles in the development of pancreatic cancer. Cigarette smoking increases the risk of pancreatic cancer, but the strength of this association is much less than for lung cancer or other smoking-related cancers. Epidemiologic studies of the effect of alcohol consumption on pancreatic cancer largely show no relationship, and the results for coffee consumption indicate little, if any, association. Human studies have suggested positive associations with meat consumption and carbohydrate intake and a protective effect of dietary fiber and consumption of fruits and vegetables. Results of a number of occupational studies are suggestive of increased risk associated with some exposures but are not fully consistent. Thus, much progress has been made in the last two decades in identifying risk factors, but much epidemiologic work is needed to identify and reduce putative exposures.

Dietary fat: gene expression and mammary tumorigenesis

Although discovered as an exogenous agent of mammary carcinoma, the mouse mammary tumor virus (MMTV) is also transmitted vertically as endogenous proviral DNA present in the germ line of all inbred mice. In the C3Hf mouse, which receives no exogenous virus, the initial event of mammary tumorigenesis is the transcription of the endogenous MMTV proviral DNA present at the Mtv-1 locus. Transcription occurs as a result of the hormonal effects of pregnancy, and Mtv-1 specific transcripts are seen in second-parity lactating mammary glands of these mice. As a means of studying the effects of diet on mammary carcinoma at the molecular/genetic level, we have studied the transcription of the Mtv-1 locus in C3Hf mice on a high-fat diet containing 46% fat in calories or a low-fat diet containing 10% fat in calories. We have detected an accelerated transcription of the Mtv-1 locus (first- vs. second-parity lactating mammary glands) in > 50% of the C3Hf mice on the high-fat diet. In addition, mice on the high-fat diet developed mammary tumors earlier (11 vs. 17.8 mos) and after fewer litters (2.1 vs. 4.2). Our results indicate that fat in the diet can affect gene expression related to mammary carcinoma.

Suppression of colonic cancer by dietary phytic acid

Large differences exist between human populations in the frequency of colonic cancer. Epidemiological evidence indicates that these differences are strongly influenced by country of residence, and a negative correlation has been found between the fiber content of the diet and frequency of colonic cancer. This has prompted the hypothesis that high-fiber diets are in some way protective. However, reanalysis of the dietary data provides equally strong support for the hypothesis that the protective element may be phytic acid (inositol hexaphosphate). This heat- and acid-stable substance is present in high concentration in many food items, including cereal grains, nuts, and seeds. Phytic acid forms chelates with various metals and suppresses damaging iron-catalyzed redox reactions. Inasmuch as colonic bacteria have been shown to produce oxygen radicals in appreciable amounts, dietary phytic acid might suppress oxidant damage to intestinal epithelium and neighboring cells. Indeed, rapidly accumulating data from animal models indicate that dietary supplementation with phytic acid may provide substantial protection against experimentally induced colonic cancer. Should further investigations yield additional support for this hypothesis, purposeful amplification of dietary phytic acid content would represent a simple method for reducing the risk of colonic carcinogenesis.

Colon cancer in Argentina. I: Risk from intake of dietary items

A case-control study has been conducted to investigate the relationship between dietary components and risk of colon cancer in the La Plata area of Argentina. Cases are 110 patients newly diagnosed with colon cancer in 10 major hospitals between 1985 and 1986. Two neighbourhood controls per case were individually matched by age, sex and place of residence. Personal interviews elicited information on frequency of consumption of 140 food items during the 5-year period up to 6 months prior to interview. Risk is analyzed by quartiles of individual food items and groups of items. Multivariate conditional logistic regression modelling indicates that consumption of eggs is associated with increased risk for colon cancer (odds ratios by quartile: 1.0, 1.58, 2.02, 4.66), as are some dairy products (ORs of 1.93 for the highest quartile of consumption of cheese). Intake of vegetables, fish and poultry is associated with statistically significant decreasing risk (ORs of 0.075, 0.39 and 0.39, for the highest categories of consumption of vegetables, fish and poultry, respectively). The risk for red meat does not consistently increase as consumption increases. Risks are not altered by the inclusion of potential confounders such as education or body mass index. These findings confirm those of several previous studies and are of particular interest, since the Argentinean diet typically includes a high intake of red meat.

Ecologic study of lung cancer risk factors in the U.S. and Japan, with special reference to smoking and diet

Lung cancer mortality rates among United States and Japanese males were compared and related to smoking and dietary data. Mortality rates increased from 1950 to 1985 in both countries, but the absolute values are consistently lower in Japan (38.2 deaths/100,000 in 1985) than in the U.S. (72.2/100,000). The proportion of smokers is higher in Japan than in the U.S. since 1955. Japanese males start smoking considerably later than U.S. males, but smoke a higher quantity of cigarettes per day. Available information on inhalation practices and yield and type of cigarettes smoked showed no differences among the two countries large enough to account for the differences in mortality rates. Further data in this regard should be obtained. Dietary data show that fat consumption (as percentage of calories) is consistently higher in the U.S. than in Japan from 1950 (40% vs. 7.9%) through 1985 (43.5% vs. 24.5%). A linear relationship is observed between lung cancer mortality and fat intake. Our data support the hypothesis that dietary habits may modulate the carcinogenic effects of tobacco smoking.

Nutrition: the need to define "optimal" intake as a basis for public policy decisions

Much of the current chronic disease incidence, notably coronary artery disease and certain types of cancer, relates to nutritionally induced metabolic overload. The evidence for this conclusion is based on extensive analytical, descriptive, and metabolic epidemiological investigations as well as critical experimental studies in animals. Dietary assessments within homogenous populations, because of inherent measurement errors and similarities in eating habits, make only limited contributions to this issue. This communication makes recommendations as to an "optimal" diet, especially for fats and fibers, as a goal for effective disease prevention that is within our reach with the appropriate support of an informed public and a cooperative food industry. To facilitate effective public health action, the "optimal" diet is called the 25/25 diet, that is, 25% of calories as fat and 25 g per day of fiber.

Breast cancer--the optimal diet

In summary, the evidence based upon global and metabolic epidemiology, and animal studies supported by biologic understanding of the various mechanisms in which dietary fat can affect promotion and progression of breast cancer supports the concept that dietary fat, in particular, certain types of fat, and dietary fiber affect the causation, promotion, and progression of breast cancer. The epidemiologic evidence of the link between breast cancer and dietary fat is still controversial due to methodological problems in designing a valid test. Also a number of studies dealt with the question of fat intake in pre-menopausal women, where admittedly the association is weak. What now needs to be done is to verify the effect of a low-fat diet in post-menopausal breast cancer patients. We suggest that a similar trial on pre-menopausal breast cancer patients in conjunction with ovarian ablation should be conducted. The question to be considered is what in terms of dose, type, and duration of fat and fiber will be required to obtain a measureable effect on the recurrence rate and survival of breast cancer patients.

Preventing breast cancer: is it possible?

Breast cancer is a common cause of suffering and death in Australia. Improvements in detection and therapy will make only small inroads into mortality, and will not reduce suffering. Reducing the incidence of breast cancer by preventive measures is a logical step, and this paper reviews how it might be achieved. Reducing the population's exposure to known risk factors for breast cancer is logical; however, the potential for improvement is limited. Reduction in age at first pregnancy is impractical and measures such as weight reduction and reducing consumption of fat and alcohol are likely to be only partially successful. Increasing activity in youth is a concept that requires further investigation, but is a possible area of promise. Exogenous hormone use probably contributes little to the incidence of breast cancer, but prescribing patterns for post-menopausal oestrogens are changing and require monitoring. The use of hormone manipulation to prevent breast cancer has considerable potential benefit. Two approaches have been proposed. The first involves reversible suppression of ovarian function by luteinizing hormone-releasing hormone (LHRH) agonists after child-bearing has finished, combined with low-dose conjugated equine oestrogen to compensate for oestrogen loss. The other involves the use of the anti-oestrogen, tamoxifen. Both measures have the potential to halve breast cancer incidence. There is some evidence that non-hormonal chemoprevention is possible, but clinical trial data are lacking.

Comparative epidemiology of cancer between the United States and Japan. A second look

Vital statistics were examined for the years 1955 through 1985 for Japanese natives and United States whites to elucidate changes in cancer mortality and related antecedent patterns of life-style in these two populations. Results show that lung cancer rates are rapidly accelerating among Japanese males as a consequence of their prior history of heavy cigarette smoking. Oropharyngeal cancer rates are also rising in Japan paralleling increases in alcohol and tobacco utilization. As the Japanese life-style and diet continue to become more "westernized," the rates of malignancies of the breast, ovary, corpus uteri, prostate, pancreas, and colon also continue to rise. Nevertheless, the mortality patterns of certain malignancies, viz., laryngeal, esophageal, and urinary bladder cancer, are discrepant with their established risk factor associations, suggesting the existence of other differences in risk factor exposure between the two countries. Epidemiologists and health educators need to develop innovative international programs of investigation and health promotion with preventive impact on common malignancies associated with risk factors of life-style.

A population-based case-control study of colorectal cancer in Majorca. I. Dietary factors

A population-based case-control study was conducted between July 1984 and February 1988 in the Spanish island of Majorca; 286 incident colorectal cancer cases, 295 population controls and 203 hospital controls were interviewed using a food frequency questionnaire. In a multivariate analysis, an increased risk of colon cancer was found for high consumption of fresh meats (RR = 2.87) while a high consumption of cruciferous vegetables afforded protection (RR = 0.48). For rectal cancer an increased risk was associated with dairy products (RR = 3.08) while a protection was afforded by consumption of cruciferae (RR = 0.50). For colorectal cancer, the cereal food group also showed an increase in risk (RR = 1.92). When cases were compared to hospital controls, the effects of cruciferae in colon and rectum and those of dairy products in rectal cancer remained. The magnitude of the RR estimates was decreased for most comparisons, although in general terms the direction of the associations was the same. In addition, univariate analyses of food groups also suggested significant increases in risk of colorectal cancer for increasing consumption of cereals, potatoes, pastry, eggs and number of meals per day. An indication was found of a reduction in risk for consumers of coffee. An analysis based on risk scores was also conducted and a 4-fold increase in the risk of colorectal cancer and a highly significant statistical trend was found for high consumption of fresh meat, dairy products and cereals combined with low consumption of cruciferae.

Leanness, peptide hormones and premenopausal breast cancer

Environmental factors promote the development of and decrease survival from Breast Cancer. Prospective morphological and hormonal studies indicate biological markers for this disease are evident in premenopausal women. The majority of premenopausal patients are non-obese (Body Mass Index, BMI less than 25). Lean women have a greater proportion of estrogen receptor negative (ER-) tumours, which may grow faster and have a higher concentration of epithelial growth factor (EGF). We have reported that lean, BMI less than 23, versus obese, BMI greater than 28, women have a different gut-pancreatic peptide hormone response to meals and that differences in these peptide hormones occur between healthy and age weight matched premenopausal patients. We hypothesize that the diet peptide hormone control of food intake in lean women is associated with the development of mammary dysplasia, change in growth factor profile and steroid hormone metabolism.

Calcium and colon cancer: a review

The role of dietary calcium as a protective factor in the etiology of colon cancer is reviewed by examining data from ecological and analytical epidemiological studies. Biological evidence that explains the mechanisms whereby calcium intake could alter risk of developing colon cancer is also presented. The data reviewed here in general support the hypothesis that dietary calcium is linked to colon cancer in a protective manner, and that it may be one component in the etiology of colon cancer which alters an individual's risk of developing the disease.

[Nutrition and the etiology of colon cancer: from descriptive epidemiology to dietary prevention]

Colon cancer is one of the most frequent forms of cancer in the Federal Republic of Germany and in most Western countries, but is, however, generally rare in Africa, Asia, and Latin America. Based on epidemiological investigations, differing dietary practices are considered to be main reason for these differences. A high fat and protein consumption was identified as a risk factor, while a high fibre content of the diet was found to be protective. Existing hypotheses of the etiology of colon cancer, which are based on the two-stage initiation-promotion model, regard interactions between initiators, promotors, and inhibitors as decisive for the final outcome of colon cancer. Possible initiators are pyrolysis products of protein-rich food (meat or fish), generated by heating, and products of metabolism of intestinal bacteria (e.g. faecal mutagens, N-nitroso compounds, transformation products of bile acids). Fats probably exert their influence only at the promotional stage. The diet-dependent bacterial formation of deoxycholic and lithocholic acids is a possible mechanism which has been experimentally substantiated. The protective effect of a diet rich in fibre seems to be mediated in particular by dilution and adsorption of harmful compounds. Further protective factors in human diet may be calcium, selenium, vitamin A and beta-carotene. In this paper, evidence, both supporting and refuting the existing hypotheses, is discussed, as well as the possibilities of dietary prevention of colon cancer.

Amount and type of fat/fiber in nutritional carcinogenesis

It is the totality of the evidence that links a high level of dietary fat to risk for breast and colon cancers. The evidence is built on descriptive epidemiology, correlation studies, migrant studies, time trends, case-control studies, metabolic epidemiology, experimental animal studies, and biological plausibility. The effects of total caloric intake or of obesity are not as relevant as the specific types and amounts of fat consumed. The effects of fiber in modulating colon cancer risk are inconsistent. This may be due, in part, to the varying effects of differing fibers. The key questions are, which fats and which fibers, and what amount of each, are of etiological and preventive significance?

Comparison of mammary adipose fatty acid composition in Japanese and American breast cancer patients

In a comparative study of the fatty acid composition of pre- and postmenopausal Japanese and Caucasian breast cancer patients, a higher concentration of linoleic acid, the obligate precursor of arachidonic acid and its metabolites including prostaglandins, was significantly higher in postmenopausal Caucasian vs. Japanese patients. Comparable levels of linoleic acid occurred in premenopausal patients. Results indicate that a difference in linoleic acid metabolism occurs in postmenopausal Caucasian but not Japanese patients and suggest dietary modification could be beneficial in this high risk group.

The use of epidemiology, scientific data, and regulatory authority to determine risk factors in cancers of some organs of the digestive system. 6. Pancreatic cancer

The etiology of pancreatic cancer remains elusive. It predominates in males and in certain ethnic populations (i.e., Polynesians and blacks). Primarily a disease of aging, it is rare in individuals under 40. Genetics is believed to play a very small part if any. While diabetics have higher than expected incidence and mortality rates, several recent studies have indicated that in most cases the diabetes is an early sign of pancreatic cancer rather than a predisposing condition. Other conditions have been infrequently reported in association with pancreatic cancer. None of them have shown a definitive associative pattern and are believed to represent coincidental occurrences. Migrant studies of Japanese immigrants implicate some type of environmental etiology, since pancreatic cancer rates increase dramatically within one to two generations. Studies on atom bomb survivors have demonstrated no link between a single intense dose of radiation and subsequent development of this disease. Workers exposed to low-level radiation have shown an increase in pancreatic cancer, but this result may reflect methodologic problems. Many chemicals have been shown to cause pancreatic cancer in animals, and chemists exhibit higher pancreatic cancer rates than expected. However, the human cases have not been traced to any specific chemical. Many other occupations besides chemistry have shown increased pancreatic cancer rates, but the common factor in these occupations is not obvious. Studies analyzing the relationship of alcohol consumption to pancreatic cancer yield conflicting results. This may be explained if the observed effects are due to a confounder, such as cigarette smoking; to an ingredient other than alcohol contained in alcoholic beverages, such as nitrosamines; or to the immunosuppressive effects of chronic excessive alcohol consumption. Smoking is the risk factor showing the most definitive and consistent results. There is little doubt that it plays an etiologic role, and it probably accounts for the higher incidence of the disease in males. Most other research does not support MacMahon's reported association between coffee drinking and pancreatic cancer. Recent studies have indicated a generally increased fluid intake in pancreatic cancer patients due to a disease-induced disturbance in glucose tolerance function. Such increased fluid intake would tend to manifest itself in the most popular beverage of the country (i.e., coffee in the United States and tea in the United Kingdom). Animal studies have indicated a link between pancreatic cancer and high fat and/or high protein diets as well as raw soybean consumption.(ABSTRACT TRUNCATED AT 400 WORDS)

Some international comparisons of mortality amenable to medical intervention

A series of outcome indicators was proposed for assessing the curative aspects of health care using several diseases for which evidence suggested that death was largely avoidable provided that appropriate medical treatment could be given in time. International data were examined for those causes for which data were readily available. Time trends in mortality were compared for each of these conditions for six countries that had experienced appreciable growth in health services during 1950-80. Mortality from the heterogeneous "avoidable" causes had declined faster than mortality from all other causes in each of the six countries. Despite problems of diagnosis, reporting, and classification of diseases that may have existed among countries, making international comparisons of absolute mortality difficult, the trends of declining mortality were similar, lending credibility to the use of these causes of mortality as indices of health care within countries. Changes within countries may also have been attributable to changes in social, environmental, genetic, and diagnostic factors, which were not examined. Nevertheless, the consistency in mortality trends for this group of "amenable" diseases suggested that improvements in medical care were a factor in their rapid decline.

The influence of dietary fat on mammary tumor metastasis in the rat

Young, virgin female Fischer 344 rats bearing the 13762 transplantable mammary tumor were fed diets containing either 5% (low-fat group) or 23% (high-fat group) corn oil for five weeks before and six weeks after tumor implantation. Animals in the two diet groups gained weight at comparable rates throughout the experiment. There was no significant difference between the low-fat and high-fat groups with respect to average tumor diameter measured twice per week for six weeks. At the time of death (6 weeks after tumor implantation), the lungs of all rats in both diet groups contained some metastatic tumor deposits; the volume of the metastases in the lungs varied widely in both groups. Numbers of metastases to regional lymph nodes and kidneys appeared unaffected by the fat content of the diet. Thus, both growth of the 13762 mammary tumor itself and metastatic spread from the tumor were comparable whether the young rats were fed a high-fat or a low-fat diet.

Decline in mortality in Japan, USA, and the Federal Republic of Germany--the contribution of the specific causes of death

In Japan, total mortality of men and women in the age groups of 45-54, 55-64, and 65-74 years decreased, within the last three decades, by 50-60% to values which are now among the lowest in the world. During the same period, death rates of men decreased by approx. 20% in the USA and approx. 10% in the Federal Republic of Germany (FRG). As to women, decreases in both countries were over 30%. The decrease between 1968 and 1978 (period of validity of the 8th Revision of the ICD) in the three countries was mostly due to the diseases of the circulatory system: In Japan, mostly to cerebrovascular diseases, in the USA, to ischaemic heart diseases, and in the FRG, to other forms of heart diseases. Second to the diseases of the circulatory system, stomach cancer and infective and parasitic diseases contributed most to the total decrease in Japan, accidents and diseases of the respiratory system in the USA, and diseases of the respiratory and digestive systems in the FRG. The highest percentage increases of death rates for the specific causes were recorded for lung cancer in all three countries and for other forms of heart diseases in the USA.

Dietary suppression of colonic cancer. Fiber or phytate?

The incidence of colonic cancer differs widely between various human populations. It has been suggested that dietary fiber content is of utmost importance and is inversely related to the occurrence of colonic cancer. However, high-fiber diets are not always correlated with low frequency of colonic cancer, suggesting the involvement of additional dietary constituents. Inositol hexaphosphate (phytic acid) is an abundant plant seed component present in many, but not all, fiber-rich diets. The authors have found that phytic acid is a potent inhibitor of iron-mediated generation of the hazardous oxidant, hydroxyl radical. Herein, the authors propose that inhibition of intracolonic hydroxyl radical generation, via the chelation of reactive iron by phytic acid, may help explain the suppression of colonic carcinogenesis and other inflammatory bowel diseases by diets rich in phytic acid.

Mortality from prostate cancer in Italy: 1950-1979. Cross-sectional rates and cohort analysis

This paper studies prostate cancer mortality in Italy from 1950-1979 to evaluate its importance in relation to total cancers, examine the time trend for forecasting future mortality trends, and makes an attempt to interpretate mortality by analyzing demographic and risk factors. In the Authors' opinion findings from cross-sectional rates, cohort analysis and Devesa-Schneiderman method, indicate that in Italy even if the age-adjusted mortality rate has nearly doubled over the period, as in many other countries, mortality can be expected to remain constant or decrease in the future, since the data to hand show a decreasing trend in some age cohorts.

Influence of diet on 1,2-dimethylhydrazine metabolism in rat liver

The metabolism of 1,2-dimethylhydrazine (DMH) was investigated in isolated perfused livers excised from Sprague-Dawley rats fed four semisynthetic diets over two generations. The diets were varied within normal physiological limits, without producing specific deficiencies. Diet was shown to have an influence on the growth of animals and on the cholesterol content and beta-glucuronidase activity in the blood serum. However, diet did not influence the rate of metabolism of DMH or the concentration of metabolites.

Glycolytic overload and the genesis of breast cancer

It is suggested that the development of breast cancer is due to overloading of the glycolytic pathways. An excess of substrates or an excessive delivery rate of substrates to the Krebs Cycle is believed to result in the formation of acetyl CoA. Feedback mechanisms controlling the conversion of acetyl CoA to cholesterol may be overcome; the resulting high concentration of cholesterol induces the formation of pregnenolone which may then be converted into androgens, estrogens and progesterone. These steroids are in addition to those produced by gonads and adrenal glands. Glycolytic overload is also associated with an increase in fat stores which have been shown to be the site of interconversion of sex hormones. Excess sex hormones or abnormal sex hormones are believed to be the cause of breast cancer. The hypothesis presented links glycolytic overload with clinical biochemical phenomena and explains some of the anomalies observed in breast cancer experience in different ethnic groups. Changes in dietary habits during the history of man resulting in " gorging " and the consumption of highly refined sugars are possible causes of glycolytic overload. So, also, is impaired thermogenesis due to Brown Fat deficits in certain ethnic groups.

The role of genotoxic carcinogens and of promoters in carcinogenesis and in human cancer causation

The majority of human cancers have multifactorial environmental causes stemming mainly from lifestyle factors such as use of tobacco products through cigarette smoking, snuff dipping, or chewing, and specific nutritional elements and dietary practices. The mechanisms of these lifestyle factors can be analyzed in terms of specific genotoxic carcinogens, and of epigenetic agents or promoting factors. Tobacco and tobacco smoke contain not only genotoxic carcinogens but also, with a more important ultimate effect, cocarcinogens and promoters. Alcohol acts as a cocarcinogen with tobacco, possibly by modifying the metabolism of carcinogens in select organs. Genotoxic carcinogens as nutritional factors may be found in pickled, salted, and smoked foods and may be responsible for gastric cancer. Vitamins C and E and other antioxidants are effective inhibitors. Other types of genotoxic carcinogens are mutagenic chemicals found in broiled and fried foods, and these may be involved in cancer of the colon, breast, and prostate. Promoting effects derive from a high level of dietary fat, which has been linked epidemiologically and through laboratory studies to a higher risk for these cancers. Possible mechanisms by which fat exerts its effects are an increased concentration of bile acids in the stool, as related to colon cancer, and which may be countered by a high cereal fiber diet, to increase stool bulk. In relation to breast or prostate cancer, fat may exert its effect on complex hormonal balances, and also on membrane composition. These promoting effects, whether associated with tobacco smoke or nutrition, are highly dose-dependent, and provided the insult is not too far advanced, reversible. Thus, lowering the dosage, or eliminating the effect as in smoking cessation should have an appreciable effect in reducing overt disease development, and do so fairly promptly. This may apply also to a reduction of second disease in cases where a first occurrence has been successfully treated by conventional means.