Diet and endocrine-related cancer

Racial differences in premenopausal endogenous hormones

Differences in breast cancer incidence across racial groups are well documented. African Americans have the highest rates of premenopausal breast cancer and Asians have lower breast cancer rates across all age groups. We hypothesized that levels of premenopausal endogenous hormones and growth factors, risk factors that have been predictive of breast cancer, would differ by race. Using a cross-sectional study design, we tested this hypothesis in the Nurses' Health Study II. We assayed estradiol, progesterone, prolactin, sex hormone binding globulin (SHBG), insulin-like growth factor-I (IGF-I), and IGFBP-3 in 111 African American and 111 Asian American women, matched to 111 Caucasian women on age, day of luteal phase, and day, time, and fasting status at blood collection. We analyzed the association between race and hormone levels using robust linear regression methods. In multivariate models, compared with Caucasians, African Americans had 18% higher levels of estradiol (P < 0.01), 17% higher free estradiol (P < 0.01), 11% lower SHBG (P = 0.05), 11% higher IGF-I (P < 0.01), 25% higher free IGF-I (P < 0.01), and 9% lower IGFBP-3 (P < 0.01) levels. In multivariate models, compared with Caucasian women, Asian Americans had 22% higher calculated free estradiol (P < 0.01), 31% lower SHBG (P < 0.01), and 25% higher free IGF-I (P < 0.01) levels. No racial differences were found in progesterone and prolactin levels. Our study showed hormone differences consistent with breast cancer risk between Caucasians and African Americans but inconsistent with breast cancer risk between Asian Americans and Caucasians. Further research is needed to explore differences across racial groups and the link between endogenous hormones and breast cancer risk.

Review of the effects of dietary fat on experimental mammary gland tumorigenesis: role of lipid peroxidation

The purpose of this communication is threefold, that is, (1) to review and critique the studies designed to examine the interrelationship between dietary fat and experimental rodent mammary gland tumorigenesis, (2) to assess the influence of dietary fat on growth of human breast carcinoma transplants in immunodeficient mice, and (3) to examine and discuss the role of products of lipid peroxidation in these tumorigenic processes. It is concluded from this review and critique that the amount and type of dietary fat can significantly influence the development and/or growth of rodent mammary gland tumors and growth of human breast carcinomas in immune deficient mice. Dietary fat can be either stimulatory or inhibitory to these tumorigenic processes, phenomena that could be a function, at least in part, of the generation of products of lipid peroxidation.

Elevated serum dehydroepiandrosterone sulfate levels in practitioners of the Transcendental Meditation (TM) and TM-Sidhi programs

Serum dehydroepiandrosterone sulfate (DHEA-S) levels were measured in 270 men and 153 women who were experienced practitioners of the Transcendental Meditation (TM) and TM-Sidhi programs, mental techniques practiced twice daily, sitting quietly with the eyes closed. These were compared according to sex and 5-year age grouping to 799 male and 453 female nonmeditators. The mean DHEA-S levels in the TM group were higher in all 11 of the age groups measured in women and in 6 of 7 5-year age groups over 40 in men. There were no systematic differences in younger men. Simple regression using TM-group data revealed that this effect was independent of diet, body mass index, and exercise. The mean TM-group levels measured in all women and in the older men were generally comparable to those of nonmeditator groups 5 to 10 years younger. These findings suggest that some characteristics of TM practitioners are modifying the age-related deterioration in DHEA-S secretion by the adrenal cortex.

Dietary fat, calories, and mammary gland tumorigenesis

In this communication, a vast array of studies designed to examine the relationship between dietary fat and experimental mammary gland tumorigenesis was reviewed and critiqued. It is clear, as reported by many laboratories, that as the fat content of the diet is increased from a low or standard level to a high level, a consistent and substantial increase in the development of rodent mammary gland tumors is observed. The longer the duration the high-fat diet is fed, the greater the enhancing effect on tumorigenesis. Furthermore, the stimulatory effect of a high-fat diet is observed even when fed commencing late in an animal's life. A multitude of studies also have provided evidence that the type of fat can markedly influence the development of rodent mammary gland tumors. In general, high dietary levels of unsaturated fats (e.g., corn oil, sunflower-seed oil) stimulate this tumorigenic process more than high levels of saturated fats (e.g., beef tallow, coconut oil); diets rich in certain fish oils (e.g., Menhaden oil, Max EPA) are often the most inhibitory to this tumorigenic process. Importantly, however, supplementation of saturated fat or fish oil diets with modest amounts of unsaturated fats, e.g., corn oil, often negates the mammary tumor inhibitory activities of these fats. Thus, rather extreme differences in the types of fat are required for a differential in mammary gland tumorigenesis; common proportionate blends of different fats of animal, plant, and/or fish origin are often unable to differentially influence this tumorigenic process. Diets rich in monoenoic fatty acids, e.g., those containing high levels of olive oil, have been examined in a number of studies; results from these studies have been inconsistent. A number of reports suggest that the increase in development of mammary tumors in rodents fed a high-fat diet, compared with those fed a low-fat diet, is due to specific metabolic activities of the fat per se, activities independent of a caloric mechanism. Careful analysis of these reports suggest that such a conclusion may not be totally warranted. Indeed, persuasive evidence is accumulating indicating that the major mammary tumor development enhancing activities of a high-fat diet may be via a caloric (energy) mechanism. Caloric restriction, even in animals fed a high-fat diet, significantly suppresses mammary tumor development. Even mild caloric restriction (e.g., 12%) can significantly suppress development of mammary tumors in rodents.(ABSTRACT TRUNCATED AT 400 WORDS)

Vegetable and fruit consumption and cancer risk

The relationship between cancer risk and frequency of consumption of green vegetables and fruit has been analyzed using data from an integrated series of case-control studies conducted in northern Italy between 1983 and 1990. The overall dataset included the following histologically confirmed cancers: oral cavity and pharynx, 119; oesophagus, 294; stomach, 564; colon, 673; rectum, 406; liver, 258; gall-bladder, 41; pancreas, 303; larynx, 149; breast, 2,860; endometrium, 567; ovary, 742; prostate, 107; bladder, 365; kidney, 147; thyroid, 120; Hodgkin's disease, 72; non-Hodgkin lymphomas, 173; myelomas, 117; and a total of 6,147 controls admitted to hospital for acute non-neoplastic conditions, unrelated to long-term dietary modifications. Multivariate relative risks (RR) for subsequent tertiles of vegetable and fruit consumption were derived after allowance for age, sex, area of residence, education and smoking. For vegetables, there was a consistent pattern of protection for all epithelial cancers, with RRs in the upper tertile ranging from 0.2 for oesophagus, liver and larynx to 0.7 for breast. All the trends in risk were in the same direction and significant for all carcinomas except gall-bladder. In contrast, no protection was afforded by high vegetable consumption against non-epithelial lymphoid neoplasms. With reference to fruit, strong inverse relationships were observed for cancers of the upper digestive and respiratory tract, with RRs in the upper tertile between 0.2 and 0.3 for oral cavity and pharynx, oesophagus and larynx relative to the lowest tertile. The lower the location of the tumour in the digestive tract, the weaker appeared to be the protection afforded. Significant inverse relationships were observed for liver, pancreas, prostate and urinary sites, but not for rectum, breast and female genital cancers or thyroid. No relationship emerged for lymphomas and myelomas. Even in the absence of a clear biological interpretation, the consistency and strength of the patterns observed indicate that, in this population, frequent green vegetable intake is associated with a substantial reduction of risk for several common epithelial cancers, and that fruit intake has a favourable effect, especially on upper digestive cancers and, probably, also on urinary tract neoplasms.

Estradiol binding to plasma proteins after changing to a low-fat diet

Breast cancer development is believed to be associated with both dietary fat consumption and the proportion of biologically available estradiol in the serum. A study was undertaken to determine if a reduction in fat consumption would influence the binding, and thus the bioavailability, of estradiol. Groups of pre- and postmenopausal women were randomized to begin either a standard western diet (40% energy from fat) or a low-fat diet (20% energy from fat). After two months, each woman changed over to the alternate diet. Blood samples were taken at the end of each dietary period. Change of diet made no significant difference to the proportions of nonprotein-bound (free), albumin-bound, or sex hormone binding globulin-bound estradiol in this study. However, the number of women studied and the duration of change were relatively small.

Diet and cancer. Evidence from associations of multiple primary cancers in the SEER program

The occurrence of multiple primary cancers may reflect common etiologic factors. We investigated the extent to which the diet and cancer hypothesis was supported by data from the Surveillance, Epidemiology, and End Results (SEER) Program on multiple primary associations. Cancers of the colon/rectum and prostate in men, and those of the breast, colon/rectum, and uterine corpus in women, were hypothesized a priori to be diet-related cancers. Of the eight multiple primary associations among diet-related cancers that were possible in men and women, relative risks (RR) of a second diet-related primary cancer developing after a first diet-related primary ranged from 1.06 to 1.43. The lower bound of the 99% confidence intervals (CI) for five of these associations exceeded 1.00, and fell between 0.95 and 0.99 for the other three associations. The observed multiple primary associations were compatible with the existence of common etiologic dietary elements. However, hormonal, immunologic, and medical care factors shared by these malignancies must be considered as alternative explanations for these findings.

The binding of blood-borne estrogens in normal vegetarian and omnivorous women and the risk of breast cancer

Serial blood samples were taken at two-hour intervals over a 24-hour period from 25 premenopausal vegetarians (12 vegans and 13 ovolactovegetarians) and from 21 omnivorous controls. All members of the former group had been on a vegetarian diet for a minimum of three years. The mean proportion of estradiol unbound to blood proteins was similar in both vegetarians (1.26%) and meat eaters (1.16%). However, the amount bound to albumin was significantly raised in vegetarians (50.1% vs. 43.1%, p less than 0.009), whereas that bound to sex hormone-binding globulin (SHBG) was correspondingly lower (48.7% vs. 55.8%, p = 0.01). Mean levels of SHBG were similar in vegetarians (59.9 nmole/l) and omnivores (62.0 nmole/l), as was the total amount of free fatty acid (0.42 mmole/l for both). Within the vegetarian group, no differences were detected between vegans and ovolactovegetarians.

Nutritional cancer risks derived from energy and fat

Both animal and human studies indicate that increased caloric intake and increases in body weight and obesity are associated with increased risk of cancer of the breast, endometrium, ovaries, colon, rectum and prostate. Recent animal studies indicate that it is the total caloric intake, rather than the percent of fat in the diet, that is associated with tumorigenesis and carcinogenesis, and that tumor development depends on a complex interaction involving energy intake, energy expenditure, energy retention within the body (body fat vs lean body mass) and body size. Omega-3 fatty acids inhibit tumorigenesis and tumor growth in many cancer models in rodents. Exercise diminishes tumor formation in mice, rats and humans. Exercise delays mortality from all causes, and life-long exercise is associated with decreased cancers of the breast and reproductive system in women, and cancer of the colon in women and men.

Effects of fatty acids on gap junctional communication: possible role in tumor promotion by dietary fat

Dietary lipids, in particular unsaturated fat, promote the development of many experimental tumors. However, no mechanisms to fully explain these effects have been elucidated. Recent reports, which we summarize here, suggest a role for gap junction-mediated intercellular communication in the process of tumor promotion. We also review tumor-promoting effects of dietary fat on experimental, particularly mammary, carcinogenesis. Our main focus is to review recent data examining the inhibitory effects of unsaturated fatty acids on metabolic cooperation in Chinese hamster V79 cells. These data suggest that inhibition of junctional communication may be involved mechanistically in the promotion of tumors by high levels of dietary unsaturated fat. Finally, potential mechanisms by which unsaturated fatty acids inhibit metabolic cooperation are examined.

Cultural significance and physiological manifestations of menopause. A biocultural analysis

The perception and experiences of menopause vary cross-culturally. However, the lack of physiological symptoms such as hot flashes, in some cultures, calls for more explanations beyond social and cultural factors alone. Like other developmental events, menopause is a biocultural experience. Therefore, research on menopause should consider biocultural factors such as environment, diet, fertility patterns and genetic differences that may be involved in the variations of menopausal experience.

Relation between tumour size and plasma prolactin levels in premenopausal patients with breast carcinoma. A preliminary report

In thirty-one premenopausal patients with carcinoma of the breast the plasma prolactin was measured after mastectomy. A highly significant correlation between tumour size and plasma prolactin levels (p less than 0.002) was observed after adjustment for age at diagnosis and parity. At the time of the prolactin determination no clinical signs of metastatic disease were evident, suggesting that the prolactin levels were unrelated to the tumour burden.

Nutrient intake and hormonal status of premenopausal vegetarian Seventh-day Adventists and premenopausal nonvegetarians

The relationship between dietary nutrients and plasma estrone, estradiol-17 beta, estriol, dehydroepiandrosterone sulfate, and prolactin levels was investigated in 14 premenopausal Seventh-day Adventist vegetarian (SV) women and 9 premenopausal non-Seventh-day Adventist nonvegetarian (NV) women. The SV subjects consumed less fat, especially saturated fat, and used significantly less fried food than the NV subjects. Plasma levels of estrone and estradiol-17 beta in the SV subjects were significantly lower than in the NV subjects. SV estradiol-17 beta and estriol levels were positively correlated with linoleic acid and protein intake, while NV prolactin levels were significantly correlated with intakes of oleic and linoleic acids and total fat. The data suggest that specific dietary nutrients were related to the hormonal milieu of these SV and NV subjects.

Blood hormone profiles in prostate cancer patients in high-risk and low-risk populations

Epidemiologic data reveal that the incidence rate of prostate gland carcinoma among the black population in the United States (US) is several times higher than among Nigerians. A collaborative study between the two countries was undertaken, and blood hormone (testosterone [T], dihydrotestosterone [DHT], estrone [E1], estradiol [E2], and prolactin [P1]), total acid phosphatase (TP), and prostatic acid phosphatase (PAP) profiles in the two population groups were compared. In the US groups (patients and controls) there were significantly higher levels of T (P less than 0.01) and E1 (P less than 0.05) compared with the Nigerians. Also, the US patients had significantly higher levels of T (P less than 0.05) and E1 (P less than 0.01) compared with their matched controls. In the Nigerians T but not E1 levels were significantly lower (P less than 0.05) in patients compared with controls. DHT, E2, and P1 were not significantly different in patients and controls between and within the populations. Nigerian patients had higher levels (P less than 0.001) of TP and PAP compared with US patients. It is concluded that differences in blood hormone profiles in the two population groups are based on factors other than the genetic makeup of the populations.

Trends in diet and breast cancer mortality in England and Wales 1928-1977

Trends in age-adjusted breast cancer mortality and consumption of meat, fat, sugar, cereal, and fruit and vegetables were studied for England and Wales over the 50-year period from 1928 to 1977. At the onset of World War II, there was a marked reduction in both breast cancer mortality and intake of sugar, meat and fat, and an increased consumption of cereals and vegetables. Consumption of these foodstuffs returned to pre-war levels by 1954, but breast cancer mortality did not return to pre-war levels until some 15 years later. The association between the various dietary components and subsequent breast cancer mortality was determined for various lag intervals. Significant correlations were found for cereal, fat, sugar and meat consumption, the correlation being maximal for a diet-breast cancer death lag interval of 12 years. These findings add weight to the hypothesis that breast cancer development is related to a diet rich in meat, fat and sugar, and that some protection against cancer may be afforded by a reduction in these dietary components and an increase in cereal consumption.

Dietary patterns and cancer of the digestive tract in older patients

This study involved 97 male veterans (age range, 45-65) in four approximately equal groups, classified as follows: 1) colon or rectal cancer, 2) upper digestive-tract cancers, 3) other cancers, and 4) additional controls (no cancer). Dietary histories of these cancer and noncancer inpatients were recorded to see whether or not consumption of particular substances could be predictive of cancer. The interactions of substances in combination such as sugar x fat, and alcohol x smoking, proved to be important predictors of cancer of the upper digestive tract. The degree of coffee consumption was a predictor of nondigestive-tract cancer. However, colorectal cancer patients could not be distinguished from non-cancer patients by the dietary variables examined.

Dietary factors related to breast cancer

It is becoming increasingly accepted that the ingestion of dietary fat is one of the major environmental factors involved in the development of breast cancer. Laboratory data and epidemiologic evidence supporting the association are discussed in relation to the etiology of this diseae, which strikes one out of every 11 American women. Although the mechanism by which fat exerts its influence on breast cancer development remains to be more fully understood, it is recommended that a dietary regimen with a decrease in fat consumption be adopted to effect a reduction in breast cancer incidence. The eventual prevention of breast cancer will require additional and closer cooperation between epidemiologists, endocrinologists, nutritionists, chemists, cell biologists, and public health specialists.

Nutrition and age at first birth in breast-cancer risk

Urban/rural breast-cancer incidence ratios in the state of Iowa for 1950 and 1969-71 were contrasted with corresponding urban and rural distributions of age-at-first-birth and population nutrition, variable measured approximately 15 years before each morbidity survey and putatively related to breast-cancer incidence. Over the study interval, the decline in the urban/rural breast-cancer incidence ratio correlated better with changing nutritional patterns than with changing age-at-first-birth.

Effect of a vegetarian diet and dexamethasone on plasma prolactin, testosterone and dehydroepiandrosterone in men and women

This study reports the effect of a vegetarian diet and dexamethasone administration on the hormone status of healthy Caucasian men and premenopausal women. A lower nocturnal release of prolactin and testosterone occurred in men fed a vegetarian diet, while in women, dexamethasone administration decreased the nocturnal release of prolactin and caused a greater decrease of plasma dehydroepiandrosterone (DHEA). These results show that diet modification can induce hormonal changes, If similar changes occur in patients with breast and/or prostatic cancer, diet modification may be of benefit in these patients with tumors known to be hormonally dependent.

Dietary habits and cancer epidemiology

Data indicate that most cancers appear to be related to environmental factors and that diet is one of these factors which appears to play a vital role. Epidemiologic evidence has increasingly implicated nutritional factors in the etiology of several forms of cancer in man. The effect of specific nutritional deficiencies, as well as unbalanced metabolism from dietary excesses, is discussed in relation to colon and breast cancer development. The possibility that excessive alcohol consumption among smokers, with its associated nutritional deficiencies, could act as a tumor promoter is discussed. It is timely to integrate the work of related specialties in cancer research, for cancer can no longer be viewed as a single disease with a single etiology.

The cause of species differences in mammary tumourigenesis: significance of mammary gland DNA synthesis

The causes of species differences in mammary tumourigenesis are briefly discussed from the genetical and environmental points of view, although no firm conclusions can be drawn. Distinct differences in mammary gland DNA synthesis were found between female mice and rats, which behave very differently in mammary tumourigenesis. Based on the importance of mammary gland DNA synthesis in mammary tumourigenesis, the differences in mammary gland DNA synthesis between species is hypothesized to be a major cause of the species differences in mammary tumourigenesis.