Diet and cancer--an overview (second of two parts)

The alpha-tocopherol, beta-carotene lung cancer prevention study: design, methods, participant characteristics, and compliance. The ATBC Cancer Prevention Study Group

The Alpha-Tocopherol, Beta-Carotene (ATBC) Lung Cancer Prevention Study was a randomized, double-blind, placebo-controlled, 2 x 2 factorial design, primary prevention trial testing the hypothesis that alpha-tocopherol (50 mg/day) and beta-carotene (20 mg/day) supplements reduce the incidence of lung cancer and possibly other cancers. Total and disease-specific mortality and incidence of various diseases and symptoms were monitored for safety. Between 1985 and 1993, 29,133 eligible male smokers aged 50 to 69 years at entry were randomized to receive daily active supplements or placebo capsules for 5 to 8 years (median 6.1 years), accumulating 169,751 follow-up years. This report describes the study design, methods, and protocol as well as the baseline characteristics and capsule compliance of the participants. The ATBC Study is the largest lung cancer chemoprevention trial conducted to date.

Sugar, meat, and fat intake, and non-dietary risk factors for colon cancer incidence in Iowa women (United States)

To investigate the relation of dietary intakes of sucrose, meat, and fat, and anthropometric, lifestyle, hormonal, and reproductive factors to colon cancer incidence, data were analyzed from a prospective cohort study of 35,215 Iowa (United States) women, aged 55-69 years and without a history of cancer, who completed mailed dietary and other questionnaires in 1986. Through 1990, 212 incident cases of colon cancer were documented. Proportional hazards regression was used to adjust for age and other risk factors. Risk factors found to be associated significantly with colon cancer included: (i) sucrose-containing foods and beverages other than ice cream/milk; relative risks (RR) across the quintiles = 1.00, 1.73, 1.56, 1.54, and 2.00 (95% confidence intervals [CI] for quintiles two and five exclude 1.0); (ii) sucrose; RR across the quintiles = 1.00, 1.70, 1.81, 1.82, and 1.45 (CI for quintiles two through four exclude 1.0); (iii) height; RR = 1.23 for highest to lowest quintile (P for trend = 0.02); (iv) body mass index; RR = 1.41 for highest to lowest quintile (P for trend = 0.03); and (v) number of livebirths, RR = 1.59 for having had one to two livebirths and 1.80 for having had three or more livebirths compared with having had none (P for trend = 0.04). These data support hypotheses that sucrose intake or being tall or obese increases colon cancer risk; run contrary to the hypothesis that increased parity decreases risk; support previous findings of no association with demographic factors other than age, cigarette smoking, or use of oral contraceptives or estrogen replacement therapy; and raise questions regarding previous associations with meat, fat, protein, and physical activity.

Trends in colorectal cancer incidence and histologic findings in Maori and Polynesian residents of New Zealand

BACKGROUND

The aim of this study was to combine an epidemiologic survey of colorectal cancer among Maori, Polynesian, and white inhabitants of New Zealand with a detailed analysis of tumor subsite and histopathology.

METHODS

Data were obtained from the New Zealand National Cancer Registry and included all registrants from 1970 to 1984. Sections of histologic specimens of colorectal cancer of Maori and non-Maori were retrieved from three Auckland hospitals.

RESULTS

The annual age-adjusted incidence rates of large intestinal cancer among male and female Maoris and male and female Polynesians were 40%, 40%, 39%, and 29%, respectively, of the total population incidence. Time-trend analysis showed the incidence of large intestinal cancer to be increasing among all racial groups. The relative proportion of rectal cancers was higher in male and female Maoris and female Polynesians than in the general population, whereas male Polynesians had a relatively high proportion of right colonic cancers. High-grade carcinoma and mucinous carcinoma occurred more frequently in young individuals regardless of race. Carcinomas were diagnosed at a more advanced stage in Maoris.

CONCLUSION

Given the similar environmental characteristics of the three racial groups, the findings indicate the presence of powerful protective factors in Maoris and Polynesians. These could be constitutional or mediated by unrecognized dietary constituents.

Genetic mapping of a locus predisposing to human colorectal cancer

Genetic linkage analysis was used to determine whether a specific chromosomal locus could be implicated in families with a history of early onset cancer but with no other unique features. Close linkage of disease to anonymous microsatellite markers on chromosome 2 was demonstrated in two large kindreds. The pairwise lod scores for linkage to marker D2S123 in these kindreds were 6.39 and 1.45 at zero recombination, and multipoint linkage with flanking markers resulted in lod scores of 6.47 and 6.01. These results prove the existence of a genetically determined predisposition to colorectal cancer that has important ramifications for understanding and preventing this disease.

Diet and melanoma. An exploratory case-control study

This population-based case-control study contrasted nutrient intakes of 41 women with cutaneous malignant melanoma to those of 297 women sampled from the same community (Brisbane, Australia). Diet was assessed by a comprehensive food frequency questionnaire. The strong inverse relation we observed between high intakes of polyunsaturated fatty acids and melanoma (P < 0.01) adds sufficient weight to prior findings for this persisting causal hypothesis to be abandoned. A relatively strong association with alcohol was observed: Women drinking 20 g or more (two or more drinks) daily had 2.5 (odds ratio) times the risk of melanoma as nondrinkers (95% confidence interval, 0.87 to 7.4). However, previous data are inconsistent. With regard to potential protective factors, our data fit with prior speculation that antioxidants (beta-carotene and vitamin E), zinc, and iron warrant further investigation. The nonsignificant (P = 0.18) 40% reduction in risk seen for those eating the most fish (> or = 15 g daily versus < 5 g) suggests the effects of marine oils and omega-3 fatty acids may deserve specific attention.

Comparison of cereal-based diet with purified diet by short-term feeding studies in rats, mice and hamsters, with emphasis on toxicity characteristics

Animal diets used in toxicity studies are prepared either from natural ingredients (cereal-based diet) or from more refined products (purified diet). The type of diet may influence both the outcome of the study and the values obtained with the various parameters in test and control animals. To detect the parameters sensitive to changes in diet composition, short-term (4-wk) studies were conducted in rats, mice and hamsters fed either a cereal-based diet or the AIN-76A purified diet supplemented with vitamins and minerals at the highest recommended levels for each of the species used. Although the purified diet was more palatable to rats and showed a higher protein quality, growth rate and food intake were generally slightly higher with the cereal-based diet in each of the species examined. The haematological values of the two diet groups were generally comparable. On the cereal-based diet the production of faeces was considerably higher than on the purified diet and was accompanied by a higher weight of the caecum. These findings were attributed to the relatively high level and mixed composition of the fibre fraction in the cereal-based diet. Blood levels of cholesterol and phospholipids were clearly lower on the cereal-based diet than on the purified diet. Because the differences were probably due to the level and composition of the fibre fraction, they support the suggestion to replace the 5% cellulose of the AIN-76A diet by a higher level of a more composite but well defined source of dietary fibre.

Serum selenium levels in individuals on PKU diets

Serum selenium levels in 73 patients with phenylketonuria were significantly lower than in controls. The phenylketonuric and hyperphenylalaninaemic individuals taking the non-supplemented amino acid mixture generally had lower levels: 36% were below the normal range as defined by our laboratory, compared with 19% in the supplemented group. The low levels were present even in those on diet, who had a greater phenylalanine tolerance--that is, a tolerance for more than 9 x 50 mg phenylalanine exchanges per day, in other words a higher intake of natural protein. Individuals on long-term synthetic diets may be at risk for selenium deficiency even on selenium supplements. In areas where the soil may be low in selenium, the deficiency may be aggravated. Long-term low levels may impair health but the required amount of selenium supplementation remains uncertain.

Vegetables, fruit, and cancer. II. Mechanisms

The epidemiologic literature on the relationship between vegetable and fruit consumption and human cancer at a variety of sites was reviewed systematically in Part I. It was concluded that consumption of higher levels of vegetables and fruit is associated consistently, although not universally, with a reduced risk of cancer at most sites, and particularly with epithelial cancers of the alimentary and respiratory tracts. Possible mechanisms by which vegetable and fruit intake might alter risk of cancer are addressed here. A large number of potentially anticarcinogenic agents are found in these food sources, including carotenoids, vitamins C and E, selenium, dietary fiber, dithiolthiones, glucosinolates and indoles, isothiocyanates, flavonoids, phenols, protease inhibitors, plant sterols, allium compounds, and limonene. These agents have both complementary and overlapping mechanisms of action, including the induction of detoxification enzymes, inhibition of nitrosamine formation, provision of substrate for formation of antineoplastic agents, dilution and binding of carcinogens in the digestive tract, alteration of hormone metabolism, antioxidant effects, and others. It appears extremely unlikely that any one substance is responsible for all the associations seen. Possible adverse effects of vegetable and fruit consumption are also examined. One way to consider the relationships reviewed here is to hypothesize that humans are adapted to a high intake of plant foods that supply substances crucial to the maintenance of the organism, but only some of which are currently called 'essential nutrients.' Cancer may be the result of reducing the level of intake of foods that are metabolically necessary--it may be a disease of maladaptation.

Lipid absorption and intestinal tumour incidence in rats fed on varying levels of calcium and butterfat

The purpose of the 2 x 2 factorial study was to determine the effect of varying levels of dietary calcium (2.5 and 10 g/kg) and butterfat (50 and 200 g/kg) on lipid utilization and on development of colon tumours in animals initiated with 1,2-dimethylhydrazine dihydrochloride. Among rats fed on 200 g butterfat/kg, the fourfold increase in Ca intake induced more than a sevenfold increase in faecal excretion of total lipids and almost a fortyfold increase in faecal excretion of acid-extractable lipid. Among rats fed on 50 g butterfat/kg, the ingestion of supplemental Ca had a less dramatic effect and induced only a twofold increase in faecal excretion of total lipids and a threefold increase in acid-extractable lipid. The volume of intestinal adenocarcinomas was correlated with the excretion of acid-extractable lipid in faeces (R 0.369, P less than 0.02). Caecal enzymic activity was not correlated with tumour incidence or size or faecal lipid excretion. Overall, the fourfold increase in Ca intakes decreased total lipid absorption significantly but by less than 6%.

Effect of dietary lipids on hepatic and intestinal monooxygenases in mice

The effect of dietary lipids on hepatic and intestinal monooxygenases was studied by feeding C57BL/6N mice (for 2 wks) diets containing 5% and 23.5% (wt/wt) olive oil or corn oil. At the end of the feeding period, we measured arylhydrocarbon hydroxylase (AHH) activity in S9 preparations from liver, small intestine, and colon; and, using the same S9 preparations from the liver, we observed the activation of the following three dietary promutagens: 2-amino-3-methylimidazo(4,5-f)quinoline, 2-amino-3,8-dimethylimidazo(4,5-f) quinoxaline, and 2-amino-6-methyldipyrido(1,2-a:3',2'-d)imidazole. The results showed that high-fat diets increased hepatic AHH activity both in corn oil and olive oil diets compared with the low-fat diets; also, a 5% corn oil diet had significantly higher AHH activity compared with the 5% olive oil diet. AHH activity was, respectively, 48.6 +/- 5.1 and 79.5 +/- 11.4 pmol 3OH-benzo[a]pyrene formed/mg/min in the 5% and 23.5% olive oil diets and 66.1 +/- 5.1 and 83.9 +/- 12.2 in the 5% and 23.5% corn oil diets; values are means +/- SE, n = 16. The results also showed a significant increase in the ability of hepatic S9 fractions from animals on high-fat diets to activate promutagens in the Salmonella/plate test. On the contrary, AHH activity in the small intestine and colon was not affected by the fat content of the diet.

Natural killer cell activity in a longitudinal dietary fat intervention trial

It has been hypothesized that dietary fat may affect natural killer (NK) cell activity, a factor of potential importance in early tumor surveillance. Fourteen men successfully completed an intervention trial designed to test the effect of dietary fat on NK activity in humans. Study subjects lowered their fat intake to an average of 22% of calories as fat and consumed two dietary supplements (of coconut and safflower oils), in a cross-over design. These supplements resulted in large changes in the ratio of polyunsaturated to saturated fatty acids (1.73 to 0.34, on average). Results of a general linear model in which we fitted covariates on exercise, body mass, intervention sequence, and various dietary predictors revealed a significant effect of decreased total dietary fat intake on increased NK activity at an E/T ratio of 100:1 (about 0.79% increase for each absolute percent of calories as fat, P = 0.04). Similar results were obtained at E/T ratios of 50:1 and 25:1. No other nutritional predictor was significantly associated with NK activity at any E/T ratio.

A large-scale prospective cohort study on diet and cancer in The Netherlands

In 1986, a prospective cohort study on diet and cancer was started in The Netherlands. The cohort (n = 120, 852) of 55-69 year old men (48.2%) and women (51.8%) originates from 204 computerized municipal population registries. At baseline, participants completed a self-administered questionnaire on diet and potential confounding variables. In addition, about 67% of the participants provided toenail clippings. Cancer follow-up consists of record linkage to a pathology registry and to cancer registries. The initial interest is in stomach, colorectal, breast and lung tumors. A case-cohort approach is applied, in which detailed follow-up information of a random subcohort (n = 5000) provides an estimate of the person-time experience of the cohort. Exposure data of the subcohort will be combined with those of incident cases, yielding exposure-specific incidence rate ratios. The intraindividual variation in determinants is estimated by annually repeated measurements (n = 250) within the subcohort. The rationale, efficiency aspects and study characteristics are discussed.

Colorectal carcinogenesis

It is generally accepted that genetic and environmental factors combine in the aetiology of bowel cancer. Epidemiological studies have shown that the environmental factors effects are shown more clearly in the left colon, and that they are related to living in western societies whose diets contain high levels of protein, fat and energy. There has been recent awareness that consumption of alcoholic beverages, particularly beer, may be causally related to cancers of the left colon and rectum. This review attempts to relate the general epidemiological data to more specific mechanisms of colorectal carcinogenesis. Dimethylhydrazine (DMH) and N-nitroso chemicals are potent colorectal carcinogens in animals. They have not been thought very relevant to humans because their existence in appropriate forms in the environment has been debatable and analytical methods for the specific detection of non-volatile nitrosamines and nitrosamides have not been available. Recently, however, relevant alkylating activity has been detected in foods incubated in quasi-gastric conditions, and several epidemiological studies have shown a protective effect for Vitamin C, which may inhibit the development of rectal cancer through beer consumption. As Vitamin C prevents nitrosation and as precursors of nitrosamides are present in prepared foods, further dietary studies with hypotheses based on N-nitroso carcinogenesis are required. Unfortunately, these studies will probably not show clear dose-response relationships. Many of the complex reasons for this are discussed; however, one of the most important could be related to an interplay between inherited and environmental factors. The inherited factors demonstrated by chromosomal analysis in cancer and polyposis syndromes are a reminder that other genetic (oncogenetic) changes may occur in sporadic colorectal cancer.(ABSTRACT TRUNCATED AT 250 WORDS)

A case-control study of diet and breast cancer in Argentina

A case-control study of breast cancer was carried out in La Plata, Argentina, where the incidence of the disease is comparable to the highest rates recorded worldwide. One hundred and fifty incident cases were identified through major hospitals. For each case, a hospital control, matched by age and hospital, and a neighbourhood control, matched by residential area and age, were also chosen. Cases and controls were interviewed to obtain information on past diet, as well as demographic and socio-economic characteristics, reproductive and menstrual history and other potential breast-cancer risk factors. The dietary information was obtained from questions on the consumption of specific food items and information on portion sizes from an earlier study was used to estimate intake of calories and selected nutrients. There was a substantial excess energy intake among cases as compared to both control groups, which was present across all 3 major macronutrients which contribute to total calories. Among the food groups, the consumption of eggs was a risk factor for breast cancer, and whole-milk products and green leafy vegetables were protective. After adjusting for the calorie difference in multivariate statistical analyses of nutrients, fibre and beta-carotene consumption were weakly protective. The results are discussed with reference to possible methodological difficulties and previous studies of diet and breast cancer.

Phospholipids and fatty acids in breast cancer tissue

The fatty acid composition of fractionated phospholipids and neutral lipids was analyzed in human breast cancer tissues and the surrounding, apparently healthy tissue. In the cancer tissues the relative amounts of unsaturated fatty acids were increased in all the phospholipid subclasses analyzed. The differences were more marked in phosphatidylethanolamine than in the other phospholipid fractions and, furthermore, the relative amount of phosphatidyl-ethanolamine was increased in cancerous tissue. In blood-erythrocyte phospholipids, no differences in fatty acid composition could be found between breast cancer and control patients. The present study suggests that the lipid composition of cancerous breast tissues differs from that of the surrounding tissue and may be involved in carcinogenesis.

Homicide, suicide, motor vehicle crash, and fall mortality: United States' experience in comparative perspective

US mortality data on motor vehicle crashes, falls, suicide, and homicide for 1980 are compared with corresponding data for France, Japan, West Germany, and the United Kingdom. Unadjusted and age-specific death rates are presented, together with age-adjusted rates of years of life lost (YLL). A large male excess in rates is typical outside the fall category. Motor vehicle crashes are the predominant cause of YLL, and the United States manifests the highest YLL rates for each sex. US fall death rates at the older ages are exceeded by those of France and West Germany. The elderly generally manifest the greatest risk of suicide; American females exhibit a unique rate decline after ages 45-54 years, however. Beyond early adulthood, US suicide rates are lower than those of France, Japan, and West Germany. US homicide rates dwarf those of the comparison countries with 16- to 29-fold differentials separating prime-risk American males aged 25-34 years from their foreign counterparts.

The Skin Cancer Prevention Study: design of a clinical trial of beta-carotene among persons at high risk for nonmelanoma skin cancer

We describe a randomized clinical trial of oral beta-carotene (50 mg/day) for preventing nonmelanoma skin cancer. It is a multicenter study conducted at sites in California, Minnesota, and New Hampshire. This report describes the design of the study, baseline characteristics of the 1805 randomized patients, changes in their plasma beta-carotene and retinol levels after 1 year of treatment, and plans for statistical analyses. Important features of this study are (1) a high proportion of potential subjects were found to be ineligible or chose not to enter the study, (2) the study agent is readily available over the counter and in common foods, and (3) nonmelanoma skin cancer is a relatively minor health concern for most patients. These considerations necessitated intensive efforts to encourage compliance with the study regimen. There are also some unusual statistical features of the study. One is that the study outcome is routinely assessed only at annual examinations, so the precise time of failure cannot be identified. Also, a secondary goal of the study is to determine whether beta-carotene decreases the average number of new skin cancers per patient per year, and there are no established statistical methods for analysis of data in this situation. Alternative approaches to the analysis are discussed.

The search for the causes of breast and colon cancer

Epidemiological studies of breast and colon cancers implicate diet as a causative factor but the evidence is stronger for colon cancer, the occurrence of which may be reduced by diets with less animal fat and more fruit and vegetables.

Is there an increased incidence of adenomatous polyps in breast cancer patients?

Using flexible proctosigmoidoscopy, the incidence of adenomatous polyps was studied in 161 patients previously operated on for breast cancer and also in 147 hospitalized controls not presenting with colorectal symptoms. The acceptance and tolerance of the examination were good in both populations. The mean age and length of the colons explored were not statistically different for the two groups. The incidence of adenomas was high in the breast cancer group (14.2%) in comparison to the control group (4.7%) (P less than 0.01). This strong incidence especially concerned very small polyps with a diameter smaller than 3 mm. There were also two polyps with superficial carcinomas in the breast cancer group. Breast cancer does indeed seem to represent a condition with a high risk of colorectal adenomas. Our results prompt us to propose the adoption of systematic screening measures and a surveillance schedule as soon as the breast cancer is found.

Dietary factors and epithelial ovarian cancer

Dietary data from a population-based case-control study of 172 epithelial ovarian cancer cases and 172 controls were analysed. A significant (P less than 0.01) dose-response relationship was found between intake of fat from animal sources and risk of ovarian cancer, but plant fat was not associated. Although the effect of animal fat was confounded by education, an adjusted odds ratio of 1.8 persisted for those in the upper quartile compared to the lower quartile of consumption (P for trend = 0.03). After adjustment for animal fat intake, calorific and protein intake had minimal effects on risk. Total vegetables were found to be somewhat protective, but the mechanism of action was unclear. Weight, height and relative weight (weight/height2) were not related to risk of ovarian cancer.

[Physical occupational activity and colonic carcinoma mortality in Swiss men 1979-1982]

Colorectal cancers are the second most frequent cause of cancer death among men. To our knowledge, approximately six studies have been able to show an inverse relationship between occupational physical activity and colon cancer mortality. Information drawn from the mortality statistics for the years 1979-1982 was used to study this hypothetical association among Swiss men aged 15-79. At-risk-populations were calculated based on 1980 national census data on occupation of all Swiss men. Estimates of occupational physical activity (OPA) were based on job titles of death certificates and were "blindly" classified into three groups of low, moderate and high OPA by three independent experts. Among the cohort of 1.86 million men, 1995 deaths of colon cancer and 1066 deaths of rectal cancer occurred during the four study years. The standardized mortality ratio showed a significant, graded and inverse relationship between OPA and mortality from colon cancer but not from rectal cancer. The estimated relative risk for colon cancer of the physically inactive, as compared to those active, was 1.3 to 1.4, slightly influenced by minor differences in the way of classification of OPA. For several reasons this estimate of excess risk is probably on the low side. The subgroup of men with jobs with very high OPA showed no further reduction in risk of colon cancer, which suggests that other etiologic factors, such as diet, may play an important role. As sedentary lifestyle and colon cancer are both frequent in central Europe the hypothesized protective effect of habitual physical activity against colon cancer would seem important, especially from the public health point of view.

Prevention of cancer: vegetables and plants

1. Results of epidemiological studies indicate that a human diet rich in vegetables may lower the incidence of cancer. 2. This preventive effect of the vegetable diet against cancer could be ascribed to lowered intake of energy (joules) and its content of vitamins and carotene. 3. The consumption of vegetables means also less meat and fats as well as increased fiber content and specific chemopreventive compounds (indoles, plant phenols) present in such a diet. 4. The supposed mechanisms of prevention may include enhanced enzymatic detoxification of harmful compounds, and inhibition of their binding to cellular DNA, their adsorption on fiber, detoxification of radical forms of carcinogens by natural antioxidants in plants and probably many other ways too.

Latitudinal variation of digestive tract cancers in the US and China

Latitude influences the availability of fresh fruits and vegetables (which are associated with cancer protection) and the use of food preservation methods (which are associated with increased cancer). Such dietary differences might be reflected in the frequency of death from cancer of the digestive tract. Female mortality rates for states and provinces of the US and China, both of which cover a wide latitude range, were chosen to investigate latitude- and time-related changes. Mortality for cancer of the stomach, liver, and rectum did increase with latitude in both nations, which is consistent with the hypothesis. Exceptions were cancer of the colon and esophagus; these cancers had a variable association with latitude and did not decline markedly in the US by 1970-1979 as did mortality rates from cancer of the other digestive tract sites. Increased refrigeration and improved transportation, both of which result in increased consumption of fresh fruits and vegetables, and decreased use of older food preservation methods may be responsible for the US decline in mortality rates from stomach, liver, and rectal cancers.

Colorectal adenomas and food. A prospective study of change in volume and total mass of adenomas in man

In an endoscopic population screening study for detection of colorectal polyps the diet was registered before ascertaining whether polyps were present. Polyps less than 5 mm in diameter were followed up for 2 years before removal and histologic diagnosis. The relative risk of an increase both in the volume of registered adenomas (excluding new adenomas) and in the total mass of adenomas (including new adenomas) showed a trend towards an inverse relationship with intake of dietary fiber, non-fiber carbohydrate, and cruciferous vegetables, reaching the significance level only for intake of dietary fiber for increase of adenoma volume in men. A trend towards a positive relationship between growth and total fat intake was more inconsistent, although the significance level was reached for the relative risk of increase in adenoma mass for men. These prospective observations with regard to polyp-bearing individuals agree with previous incidence and prevalence data that have indicated a relationship between dietary habits and colorectal carcinogenesis.

Nutrient intakes of whites, blacks, and Mexican Americans in southeast Texas

Ethnic groups in the United States exhibit different patterns of cardiovascular disease and cancer morbidity and mortality. This has, in part, been attributed to differences in dietary intake. However, there is limited comparative information available regarding the dietary patterns of whites, blacks, and Hispanics residing in the same geographic area. Selected nutrient intakes were obtained by an interviewer-administered 24-hr dietary recall from 231 white, 102 black, and 98 Mexican-American persons residing in the same communities in Southeast Texas. Mean caloric intakes were highest for whites, followed by Mexican Americans and blacks. Mexican Americans had carbohydrate intakes that were significantly higher, but total fat intakes that were significantly lower, than those of whites. Blacks of both sexes had the highest cholesterol intakes and black males had the highest saturated fat intakes. Neither was significantly higher than that of whites or Mexican Americans. Overall, the mean vitamin A and C values were highest for blacks and lowest for whites, although the differences were not statistically significant. Mean calcium and phosphorus intakes were significantly higher for whites compared with those for blacks and Mexican Americans. Blacks had significantly lower mean fiber values than whites or Mexican Americans. International ethnic differences in disease distribution have long been used to provide clues to etiologic factors. National ethnic differences in disease distribution related to dietary intake can further elucidate these causative and/or preventive factors. However, to do so will require additional attention to dietary methodology of the type presented here.

Dietary fat and natural killer cell activity

Evidence from a number of sources implicates dietary fat in the etiology of various human cancers. We hypothesize a possible mechanism by which fat might increase tumorigenesis. Specifically, we discuss the connection between polyunsaturated fatty acids, prostaglandin synthesis, and the potential effect on Natural Killer (NK) cell activity. Polyunsaturated fatty acid-induced increases in series-2 prostaglandin synthesis could result in depressing NK-cell activity. As the first line of defense against tumor cells, NK-cell function may be particularly important in modifying cancer risk.

Genetic and environmental influences on premature death in adult adoptees

To assess genetic and environmental influences on adult mortality, we followed 960 families that included children born during the period 1924 through 1926 who were placed early in life with adoptive parents unrelated to them. We evaluated the risks of dying from all causes or from specific groups of causes between the ages of 16 and 58 years for adoptees with a biologic or adoptive parent who died of the same cause before the age of either 50 or 70. We compared these risks with the adoptees' risk of dying from the same causes between the ages of 16 and 58 when either the biologic or adoptive parents were still alive at the ages of 50 and 70. The death of a biologic parent before the age of 50 resulted in relative risks of death in the adoptees of 1.71 (95 percent confidence interval, 1.14 to 2.57) for all causes, 1.98 (1.25 to 3.12) for natural causes, 5.81 (2.47 to 13.7) for infections, 4.52 (1.32 to 15.4) for cardiovascular and cerebrovascular causes, and 1.19 (0.16 to 8.99) for cancers. The death of an adoptive parent resulted in relative risks of death in the adoptees that were close to unity for all causes, natural causes, and infections, 3.02 (0.72 to 12.8) for vascular causes, and 5.16 (1.20 to 22.2) for cancers. A similar but weaker pattern was observed when either a biologic or adoptive parent died before the age of 70. We conclude that premature death in adults has a strong genetic background--especially death due to infections and vascular causes.(ABSTRACT TRUNCATED AT 250 WORDS)

Cooking methods, carcinogens, and diet-cancer studies

A neglect of natural, preservative, and cooking-induced carcinogens or mutagens in food, along with a neglect of dietary patterns during the first portion of a person's lifetime, may be responsible for the many conflicting epidemiological reports dealing with dietary factors and cancer. From animal and occupational studies, we know that the two most important factors in the study of cancer are the dose of carcinogen and allowance for a long latent period. Most of the recent nutrition and cancer studies have ignored both factors. Some bile acids or other endogenous factors may be influenced by diet and may act as cancer-promoting agents, but promoting agents cannot be studied in the absence of knowledge about, or control of, the cancer-initiating events with which they must interact.

Observations of serum trace elements in chronic lymphocytic leukemia

Serum trace elements (STE) were measured in 50 patients with chronic lymphocytic leukemia (CLL) and 100 normal subjects. Copper was higher in patients than in controls (1.50 +/- 0.06 versus 1.10 +/- 0.02 micrograms/ml, P less than 0.001), increased steadily from Stage 0 to Stage 4 (P = 0.002), and correlated with the lymphocyte count and serum lactate dehydrogenase (P less than 0.01) but not with acute phase reactants. Zinc was lower in patients than in controls (0.94 +/- 0.03 versus 1.10 +/- 0.02 micrograms/ml, P less than 0.001). Zinc (NS), selenium (P = 0.039), and calcium (P = 0.033), were decreased in Stages 3-4 as compared to Stages 0-2. The copper-to-zinc ratio (CZR) increased continuously from Stage 0 to Stage 4 (P less than 0.001). Discriminant analysis between two groups, Stage 0-2 and Stage 3-4, based on serum copper, zinc, calcium, and protein levels, allowed for a correct classification of 94% of the patients. Moreover, the clinical staging of the remaining 6% was modified retrospectively according to the results of discriminant analysis. It was concluded that (1) serum copper and CZR are useful indices of the extent of disease, (2) they are independent of a nonspecific acute phase reaction, (3) STE determination could be helpful in the staging of a limited number of CLL patients, and (4) zinc deficiency could contribute to immune dysfunction in CLL.

[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.

Fatty acid patterns in triglycerides, diglycerides, free fatty acids, cholesteryl esters and phosphatidylcholine in serum from vegetarians and non-vegetarians

The differences in the fatty acid spectra of serum samples obtained from vegetarians (62 females, 40 males) and non-vegetarians (70 females, 38 males) were evaluated in a matched-pair study design. This study population made it possible to examine 48 female and 31 male pairs whose age difference did not exceed 3 years. The pairs were further matched by education, social status and health-consciousness. The fatty acid pattern of whole serum total lipids and HDL total lipids were determined by GLC. In particular linoleic, linolenic, oleic and docosahexaenoic acid reveal statistically significant differences due to different nutritional habits. A subsample (n = 20) of sera from the 2 groups was investigated by separation of lipid classes by TLC and GLC on a SP 2,340 fused-silica capillary column in order to separate cis-trans fatty acids additionally. This part of the study gives detailed information concerning the fatty acid composition of cholesteryl esters, triglycerides, diglycerides, free fatty acids and phosphatidylcholine. In all those fractions the fatty acid profiles reflect the dietary consumption of lipids. Palmitoleic, vaccenic and docosahexaenoic acid as markers of omnivorous nutrition reach levels of 5, 5 and 3% respectively in non-vegetarians, while they remain remarkably lower in vegetarians. The most prominent difference is the higher amount of linoleic acid in all lipid classes of vegetarian serum samples. The highest amount of trans fatty acids (up to 3%) was detected in di- and triglycerides.

The complementary role of primary prevention, early detection, and therapy in our fight against cancer

Public health strategies for cancer control are determined by the epidemiological, clinical and biological characteristic of each cancer. Primary prevention is most easily implemented in cancers due to one or few factors. Secondary prevention is best suited for frequent cancers with a long preclinical, detectable phase. Therapy has to be relied upon in rare cancers of unknown etiology. A critical evaluation of the accomplishments of these three approaches shows that the potential role in cancer control of early detection and treatment is severely hampered by the high social and human costs, that are only partially counterbalanced by the limited effectiveness. As a consequence, primary prevention should be regarded as the key approach to cancer control, and efforts should be concentrated on studies concerning cancer etiology and on the implementation of preventive measures.

Dietary habits and colorectal cancer incidence in a second-defined kibbutz population

The incidence of colorectal cancer in Israel is highest in European- and American-born immigrants. This is believed to be related mainly to their dietary habits. To investigate this issue further, we compared the diets of a sample of members of a well-established kibbutz (BA), which was settled by immigrants of European origin, with the diets of an age- and sex-matched sample of European-born residents of Tel-Aviv and of a previously studied kibbutz (GB). The diet of the people of kibbutz BA compared with those in Tel-Aviv was significantly lower in poultry and significantly higher in polyunsaturated fats; it also had a higher polyunsaturated/saturated fats ratio. Compared with both the Tel-Aviv residents and the kibbutz GB members, the kibbutz BA members had a significantly lower intake of saturated fats; they also had a higher intake of dietary fiber, available carbohydrates, calories, and many minerals and vitamins. However, the incidence of colorectal cancers in the kibbutz BA population was slightly, but non-significantly, higher than expected, based on age, ethnic group, sex, and calendar year-specific national incidence rates. These results are in contrast to our earlier study in which we found that kibbutz GB had less colorectal cancer than expected; thus, the results of the current study are presently unexplained.

On the age-dependent association between cancer of the breast and of the endometrium. A nationwide cohort study

The association between breast and endometrial cancer was investigated in a cohort consisting of 60,065 subjects (99% of all women in whom a first breast cancer was diagnosed in Sweden in 1960-63 and 1968-81). Complete follow-up until 1981 revealed a total of 260 endometrial cancers, as against an expected number of 151.1 (relative risk (RR) = 1.72; 95% confidence limits (CL) 1.46; 1.87). RR increased steadily from close to unity in women younger than 50 at breast cancer diagnosis to 2.40 (CL 1.97; 2.93) in those 70 years of age and older. The excess number of endometrial cancers occurred primarily during the first five years of follow-up (RR = 2.07; CL 1.79; 2.38). A common causal agency for breast and endometrial cancer is more likely to lie in environmental than in genetic factors and other observations in the same population do not support that such factors are related to characteristics of the women's reproductive histories.

Microbial oncogenesis

For more than a century, medical investigators have sought to incriminate microorganisms in the cause of cancer. The first scientific evidence of such a relationship came in 1911, with the first successful induction of a tumor using a cell-free extract. Since that time, considerable data have accrued linking retroviruses, herpes viruses, the hepatitis B virus, papovaviruses, and adenoviruses to various malignant neoplasms. There is also increasing evidence that certain bacteria and parasites participate as cofactors in the development of some cancers. Although proof of cause-and-effect relationships has been difficult to obtain, there can be little doubt that microorganisms occasionally play pivotal roles in the origin of some cancers. Whether attempted intervention against these cancers is best directed against the oncogenic microorganisms themselves or against other environmental cofactors is not yet clear. Nevertheless, the successful application of tumor vaccines in the prevention of Marek's disease in chickens and in modifying the outcome of oncogenic herpesvirus infections in nonhuman primates offers hope of at least limited application of microbial vaccines in the prevention of human cancer.

Cancer risk from inorganics

Inorganic metals and minerals for which there is evidence of carcinogenicity are identified. The risk of cancer from contact with them in the work place, the general environment, and under conditions of clinical (medical) exposure is discussed. The evidence indicates that minerals and metals most often influence cancer development through their action as cocarcinogens. The relationship between the physical form of mineral fibers, smoking and carcinogenic risk is emphasized. Metals are categorized as established (As, Be, Cr, Ni), suspected (Cd, Pb) and possible carcinogens (Table 6), based on the existing in vitro, animal experimental and human epidemiological data. Cancer risk and possible modes of action of elements in each class are discussed. Views on mechanisms that may be responsible for the carcinogenicity of metals are updated and analysed. Some specific examples of cancer risks associated with the clinical use of potentially carcinogenic metals and from radioactive pharmaceuticals used in therapy and diagnosis are presented. Questions are raised as to the effectiveness of conventional dosimetry in accurately measuring risk from radiopharmaceuticals.

Diet and breast cancer in causation and therapy

The major macronutrient associated with increased breast cancer risk is dietary fat. Evidence for this association is based on epidemiologic, clinical, and laboratory animal studies. In addition, there is suggestive epidemiologic evidence that differences in postmastectomy survival rates in Japan and the United States may be attributable to differences in dietary fat intake. The importance of the type of fat consumed, as well as its amount, has emerged as an issue of major importance. Some oils, including those rich in monounsaturates, medium chain fatty acids, or omega-3 (n-3) fatty acids appear to lack tumor-promoting effects despite their presence in the diet at high levels. Possible mechanisms by which dietary fat may exert its effects could be either direct or indirect. Direct mechanisms involve dietary modification of membrane structure and function; indirect mechanisms involve alterations in the endocrine system, and/or the metabolism of essential fatty acids to biologically active eicosanoids such as prostaglandins, and suppression of immune responses. Dietary guidelines and dietary intervention trials for the primary and secondary prevention of breast cancer are discussed.

Case-control study on colorectal cancer and diet in Marseilles

A case-control study of cancer of the colon and rectum was conducted in the Marseilles region of southern France. Cases (399) and a corresponding number of controls, matched for age and sex, were included, the controls being selected from patients undergoing functional re-education for injuries or trauma which reduced their mobility. A dietary history questionnaire was used to determine the usual eating habits during the year preceding diagnosis for cases, or preceding interview for controls. The cases reported lower consumption of vegetables and oil than controls, but no differences were seen in the consumption of meat, bread, eggs or butter. The intake of several nutrients, particularly vitamins B2, B6, C, potassium, iron, magnesium and vegetable fibre, was lower among cases. However, when all these nutrients were analysed jointly and adjusted one for the other, only potassium retained a significant effect. This may be due to the high degree of colinearity between the estimated intake of many nutrients. No association was seen with fat or fibres from cereals.

Very low sister-chromatid exchange rate in Seventh-Day Adventists

42 Seventh-Day Adventists (SDAs) and 42 controls matched for sex, age and occupation had their sister-chromatid exchange (SCE) examined in peripheral blood lymphocytes. This was done to examine if the SCE frequency was lower in this group of people, who are known to have a decreased cancer risk compared to the general population. The average SCE/cell in 30 cells from each person was 5.54 +/- 0.07 (mean +/- standard error of the mean) for the SDAs and 8.00 +/- 0.15 for the controls, the difference being statistically significant (p less than 0.00001). No difference in SCE frequency was found between SDAs eating only an ovo-lacto-vegetarian diet and those eating some fish or meat. The mitotic index (MI) was significantly higher and the replication index (RI) was significantly lower in SDAs than in controls. No correlation was found between gamma (a statistical transformation of SCEs/cell) and MI or RI within the groups of SDAs or controls. In the pooled data there was a negative correlation of gamma and MI and a positive correlation of gamma and RI. Of the interpersonal variation in gamma 8% and 14% could be explained by MI and RI. The finding of a lower SCE frequency in a group of SDAs who have a low risk of cancer might indirectly indicate a relation between SCE and cancer and encourages further studies of SCE and diet.

The unique merits of a low-fat diet for weight control

The virtual freedom from obesity enjoyed by many primitive societies may be traceable to the low fat content of their traditional diets. Recent studies indicate that humans have a very limited capacity for de novo lipogenesis from dietary carbohydrate; this implies that it should be easy to achieve negative fat balance if dietary fat intake is kept low and fat oxidation is promoted by regular exercise. Overfeeding with carbohydrate--but not with fat--provokes an insulin-mediated thermogenesis which acts to retard weight gain. Low-fat starchy foods have a relatively low caloric density, resulting in lower caloric consumption with meals. Once absorbed, carbohydrate has greater satiety value than fat. These considerations suggest that avoidance of dietary fat may be a more successful approach to weight control than "calorie counting". The efficacy of low-fat diets may be promoted by supplementary carnitine, which stimulates fat oxidation, and by chromium, which aids insulin-mediated thermogenesis. An unrefined low-fat diet, eaten to satiety and accompanied by regular exercise, may be the ideal means of maintaining a trim figure throughout life while minimizing one's risk for "Western" degenerative diseases.