A study of diet and breast cancer

Fruit, vegetables, and cancer prevention: a review of the epidemiological evidence

Approximately 200 studies that examined the relationship between fruit and vegetable intake and cancers of the lung, colon, breast, cervix, esophagus, oral cavity, stomach, bladder, pancreas, and ovary are reviewed. A statistically significant protective effect of fruit and vegetable consumption was found in 128 of 156 dietary studies in which results were expressed in terms of relative risk. For most cancer sites, persons with low fruit and vegetable intake (at least the lower one-fourth of the population) experience about twice the risk of cancer compared with those with high intake, even after control for potentially confounding factors. For lung cancer, significant protection was found in 24 of 25 studies after control for smoking in most instances. Fruits, in particular, were significantly protective in cancers of the esophagus, oral cavity, and larynx, for which 28 of 29 studies were significant. Strong evidence of a protective effect of fruit and vegetable consumption was seen in cancers of the pancreas and stomach (26 of 30 studies), as well as in colorectal and bladder cancers (23 of 38 studies). For cancers of the cervix, ovary, and endometrium, a significant protective effect was shown in 11 of 13 studies, and for breast cancer a protective effect was found to be strong and consistent in a meta analysis. It would appear that major public health benefits could be achieved by substantially increasing consumption of these foods.

No effect of adult dietary fat on tumors induced prenatally by diethylstilbestrol

Strain CD-1 female mice exposed prenatally to diethylstilbestrol (DES) or vehicle were placed on semipurified diets containing 2.6%, 10%, 20%, or 29% fat by weight at four weeks of age. These mice were used as a breeding colony for a few weeks and then maintained to terminal illness on the semipurified diets. Females exposed prenatally to DES developed mammary tumors, pituitary tumors, and glandular tumors of the reproductive tract. There was no significant difference in tumor frequency between low- and high-fat dietary groups. Fewer tumors appeared in the vehicle-exposed mice, as expected, and their frequency did not differ between the dietary groups. Pregnancy reduced tumor frequency in DES-exposed mice, but the incidence of pregnancy was not significantly different between low- and high-fat dietary groups. In the adult the failure of a high-fat diet to increase the frequency of reproductive system tumors induced prenatally is in marked contrast to the effectiveness of high-fat diets in promoting mammary tumors induced by carcinogens given to rats postnatally. This difference is critical in the interpretation of epidemiological studies. The relationship of dietary fat to reproductive system cancer in human populations was reviewed in comparison with these two animal models. The epidemiological literature was found to be more consistent with the animal model, showing high sensitivity to dietary fat prenatally but no significant sensitivity at the adult stage of life.

The association between alcohol and breast cancer risk: evidence from the combined analysis of six dietary case-control studies

Data from 1,575 cases and 1,974 controls enrolled in 6 previously conducted case-control studies of diet and breast cancer have been analysed with respect to alcohol intake. There appears to be an absence of any association between consumption of up to 40 g of alcohol per day and risk of breast cancer, and a highly statistically significant and consistent elevated risk of breast cancer for drinkers of 40 g or more of alcohol per day, for whom the relative risk, as compared with that of non-drinkers, is 1.69 (95% confidence interval 1.19 to 2.40). This association is not due to confounding by a number of diet-related factors, including total calories, fat, fibre and vitamin C.

Manipulation of body fat composition with sterculic acid can inhibit mammary carcinomas in vivo

Sterculic acid, a delta-9-desaturase inhibitor, administered to rats caused a rise in the stearic:oleic acid ratio of total lipids in peripheral red cells, serum and liver (P less than 0.001). As a reduction in the stearic:oleic acid ratio has been described in cancer cells, we investigated the effect of sterculic acid on tumour growth. Female F344 rats were injected subcutaneously with two different doses of sterculic acid for 4 weeks prior to, and 4 weeks following, implantation of a nitrosomethylurea-induced mammary tumour. Tumour growth was inhibited equally by the two doses of sterculic acid (P less than 0.001). A rise in the stearic:oleic acid ratio of tumours was observed in rats treated for only 16 days with sterculic acid. Manipulation of the tissue stearic:oleic acid ratio inhibits transplanted mammary tumour growth in rats.

Fats in seasoning and breast cancer risk: an Italian case-control study

The relationship between consumption of fat in seasoning and risk of breast cancer was considered in a case-control study conducted in northern Italy of 2663 cases of breast cancer and 2344 controls admitted in the same network of hospitals with acute, non-neoplastic and non-gynaecological conditions. Subjective scores corresponding to three levels (low, intermediate and high) of intake of butter, margarine and oil, together with a combined variable of these three items ("total fat"), were used to evaluate the personal use of fat in seasoning. Compared to low use, a slight but significant increase in risk was observed for intermediate and high intake of butter, oil and total fat with relative risks of 1.5 (95% confidence interval [CI], 1.1-1.9) for high intake of butter, 1.3 (95% CI, 1.0-1.6) for high intake of oil and 1.4 (95% CI, 1.2-1.7) for high intake of total seasoning fat. These results were not materially modified after allowance for a number of identified potentially distorting factors. The results of this study suggest that there is a positive association, although moderate, between breast cancer risk and intake of fat added in seasoning, which may represent an indirect indicator of the subject's attitude towards fat.

Occurrence of beta-hexachlorocyclohexane in breast cancer patients

The residues of polycyclic aromatic hydrocarbon (PAH) and neutral organochlorine compounds in breast fat of 44 breast cancer patients and 33 women free of cancer were determined. No statistically significant differences appeared between the two comparison groups with regard to occurrence of PAH compounds. Of the neutral organochlorine compounds, residues of beta-hexachlorocyclohexane (HCH) were found more frequently in breast cancer patients. After adjusting for age and parity by stepwise logistic regression, beta-HCH remained a significant risk factor of breast cancer. Using a cutoff point for the residue level of beta-HCH in breast adipose tissue of more than 0.1 mg/kg fat, the odds ratio was 10.51 (95% CI, 2.00-55.26).

Nutrition and breast cancer

International comparisons have provided striking correlations between fat consumption and risk of breast cancer, but these comparisons do not often consider variations in life style. Case-control studies carried out in several countries showed no real association between fat intake and breast cancer. There is some evidence that vitamin A or carotenoid intake may exert a protective effect. Alcohol intake, on the other hand, seems to be positively associated with breast cancer risk. Elevated body weight, body mass, stature, and frame size have been found to be associated as risk factors for breast cancer in women. Animal studies found that caloric restriction inhibits growth of spontaneous and induced mammary tumors, an observation that held up even when the calorie-restricted animals ingest more fat than the ad-libitum-fed controls. College women who exercise have a lower incidence of breast cancer than their more sedentary classmates. Exercise is another means of reducing caloric availability.

Diet and age at menarche

Early menarche has been associated with higher risk of breast cancer. A prospective study has been conducted in Quebec City, Canada, to evaluate the relationship of dietary intake to age at menarche. On three occasions during the schoolyear 1986-87, 2,299 pre-menarche. Incidence density ratios (IDRs) adjusted for age at entry and mothers' age at menarche were computed using proportional hazards models. IDRs for quartiles of energy, nutrient and food-group intakes were not different from the null value. In this population of well-nourished girls, diet did not influence the age at onset of menarche.

Dietary factors in aetiology and prevention of cancer in man

Chemical carcinogenesis, as presently understood, involves a number of carcinogenic factors which act in series of steps. Some industrial carcinogens may pollute the natural environment and penetrate into food. Many substances which are potent carcinogens in experimental animals exist in nature and are present in the human diet. On the other hand, many substances which are known to inhibit experimental carcinogenesis also exist in human diet. The present review discusses experimental and epidemiological data connected with the human cancer and diet. It also postulates that the dietary prevention of human cancer through "prudent" modification of diet and dietary patterns may be of importance; many of the present data are still confusing and conflicting.

Differential relationship of vitamin A and E levels in methylnitrosourea-induced Sprague-Dawley rats following prolonged feeding of fatty diets enriched with the vitamins

Prolonged supplementation of vitamins A and E (2500 IU and 11.3 IU/rat daily) in 10.3% and 21.6% fatty diets administered to methylnitrosourea-induced Sprague-Dawley rats caused alterations in plasma and liver levels of both vitamins as well as of the total lipids. Liver vitamin A levels increased steadily (more than fourfold) until termination of the experiment, whereas plasma vitamin A levels only showed a minor increase at the end of the study in comparison to rats fed a standard diet. Liver vitamin E levels initially showed no difference from those of rats treated with a standard diet, and were decreased at the end of the experiment, whereas the respective plasma levels were increased throughout the study, only showing a decrease relative to initial values at termination of the experiment. Plasma total lipids increased with age and following supplementation of the vitamins in the high-fat diet, whereas liver total lipids were influenced less by aging than by the fat and vitamin contents of the respective diets. The observed alterations were, however, not related to significant chemopreventive activity of the vitamins A and E contained in high-fat diets.

What can a woman do about her risk of dying of breast cancer?

Every day, American women are told that one in ten will develop breast cancer, and some groups perceive their risk to be so high as to justify immediate bilateral mastectomy. Many associations with breast cancer have been identified, including a history of benign breast diseases, in situ carcinoma, a family history of breast cancer, prolonged menstruation as a result of early menarche or delayed menopause, few or late pregnancies, excessive alcohol intake, obesity, and possibly the use of estrogens as oral contraceptives or postmenopausal replacement therapy. In spite of these associations, our understanding of either the cause(s) of breast cancer or the sequence of events leading to a diagnosis of breast cancer is still inadequate to make global public health recommendations regarding life style--or even to initiate well-designed studies. The epidemiologic evidence strongly suggests, however, that events relatively early in a woman's life are more important than later events, even though most of the risk of developing breast cancer will be expressed after the age of 75. Possibly one of the greatest contributions we can make to our patients' welfare is to share the knowledge that the risk of dying of breast cancer is considerably smaller than the risk of developing breast cancer; that the risk of early death from breast cancer rarely exceeds 10% in even the highest risk groups; and that the life styles most likely to reduce the risk of cardiovascular disease and other scourges of womankind are also those most likely to reduce the risk of developing breast cancer.

Dietary fat and cancer: consistency of the epidemiologic data, and disease prevention that may follow from a practical reduction in fat consumption

International variations and national time trends in disease rates suggest major associations between dietary fat and several important cancers. In contrast, case-control and cohort studies of dietary fat in relation to the same cancers generally report weak associations, or have failed to detect any association with fat intake. This study was undertaken in an attempt to understand the apparent discrepancy between these observations. The results provide an insight into the magnitude of cancer risk reduction that may follow from a practical reduction in dietary fat. Regression analyses of international variations in cancer incidence rates were used to estimate relative risks (RR) as a function of fat intakes for both males and females. These analyses focused on cancers of the breast, colon, rectum, ovary, and endometrium in females, and colon, rectum, and prostate cancers in males. Ages 55-69 and 30-44 were considered in order to compare RR estimates between an older and younger age group, and between post- and pre-menopausal women. Corresponding RR estimates were also calculated, based on the regression of changes in disease rates from the mid-1960s to 1980 on changes in dietary fat, using data from several countries. A strong degree of consistency with the RR estimates from international comparisons was observed. The international regression analyses were also used to project changes in cancer rates among Japanese migrants to the United States. A high level of consistency with the observed disease-rate changes was noted. Similarly, the international data analyses were used to project RRs for the fat intake categories used in specific case-control and cohort studies, while acknowledging measurement error in individual dietary assessment. Although certain exceptions are noted, considerable consistency was found between the aggregate and analytic data results, leaving open the strong possibility that a practical reduction in dietary fat could result in a major reduction in the incidence of several prominent cancers in the United States and in other nations having high fat consumption.

Strategies for cancer prevention through diet modification

Diet and cancer research at the National Cancer Institute has grown from a budget of $2.5 million in 1974 to $55 million in 1988. The emphasis is partially on demonstrations of prevention strategies and chemoprevention trials. Studies to disseminate dietary goals in practical ways are undertaken with the aid of the food industry.

Insulin-tumour interrelationship in EL4 lymphoma or thymoma-bearing mice. I. Alloxan-diabetic or non-diabetic mice

A study has been carried out in which a comparison was made between EL4 lymphoma (assumed to be an insulin-producing secreting tumour) and thymoma (an insulin-dependent tumour). Tumour development and incidence, 3H-thymidine incorporation and insulin content in tumours, the host's food intake, blood insulin, glucose and cholesterol were determined in non-diabetic and alloxan-diabetic mice. Whereas no significant differences were observed between the diabetic and non-diabetic EL4 tumour-bearing mice, the diabetic, thymoma tumour-bearing mice showed reduced tumour growth and lower tumour incidence as compared with their non-diabetic counterparts. Insulin administration to diabetic tumour bearing mice, enhanced 3H-thymidine incorporation in the thymoma tumour cells only, and the insulin content of the EL4 tumours was found to be higher than that of the thymoma tumours. Rapid diabetes remission was observed in the diabetic, EL4 tumour-bearing mice as compared with the thymoma tumour-bearing mice.

Feasibility of a randomized trial of a low-fat diet for the prevention of breast cancer: dietary compliance in the Women's Health Trial Vanguard Study

The Women's Health Trial Vanguard Study was conducted to examine the feasibility of a nationwide, randomized multicenter intervention trial to test the hypothesis that a low-fat diet followed for a period of 10 years will reduce breast cancer risk. Women ages 45-69 years at increased risk of breast cancer were randomized into intervention (low-fat diet, n = 184) and control (usual diet, n = 119) groups. On the basis of 4-day food records, baseline fat intakes were comparable in the two groups, averaging 1,718 kcal with 39% of energy as fat. Intervention women reported substantially lower fat intake at 6 (20.9% kcal), 12 (21.6%), and 24 months (22.6% kcal). In contrast, control women reported only slight reductions in fat intake (37.3% kcal at 12 months and 36.8% kcal at 24 months). Evidence that these women were indeed complying with the low-fat dietary intervention comes from (a) the reasonable nature of reported nutrient changes within food groups in the intervention women and (b) agreement between observed and expected differences in plasma total cholesterol between the control and the intervention groups. At 12 months, the observed control - intervention plasma cholesterol difference was 13.1 +/- 4.6 mg/dl while the expected difference based on the Keys equation was 15.1 +/- 1.1 mg/dl; at 24 months, the observed difference was 15.5 +/- 4.3 mg/dl and the expected difference was 12.0 +/- 1.2 mg/dl. These analyses indicate that the intervention women made substantial dietary changes and have successfully maintained these changes over a 2-year period. This study thus demonstrates the feasibility of a randomized trial with an intensive low-fat dietary intervention.

Diet and cancer. A review

Diet is one of the major causes of cancer. The epidemiologic data on which this conclusion is based has been derived from analytic epidemiologic studies, buttressed by descriptive (ecologic) epidemiology and studies in experimental animals. Although the evidence is not entirely consistent, high dietary fat intake appears to be a major cause of breast cancer, and more consistently, of colorectal cancer, and probably prostate cancer as well. Obesity is an important cause of endometrial cancer, and increases the risk of breast cancer in postmenopausal women, though increasingly there is evidence that suggests that obesity is protective for breast cancer in premenopausal women. There is inconsistent evidence that dietary fibre is protective for colorectal cancer, though good evidence that vegetable consumption is protective. Several studies have pointed to a protective effect of betacarotene for lung cancer, but betacarotene may be acting as an indicator of other protective factors in diet. Recommendations for dietary modification, congruent with recommendations for the prevention of cardiovascular and other chronic diseases, are now appropriate.

Energy balance, body size, and cancer

Increased energy intake and physical inactivity have been shown to heighten the risk of breast, large bowel, and other cancers. Large body size and fatness, as measured by adult stature, body weight and body mass indices, are positively related to a variety of cancers, including breast, colorectum, prostate, endometrium, kidney, and ovary, as well as to total cancer incidence or mortality in many investigations, although conflicting reports exist. Adult weight gain has also been specifically implicated in a few etiologic studies of breast and large bowel cancer. Furthermore, increased birthweight and childhood stature have been linked to increased risk of leukemia, lymphoma, osteogenic sarcoma, and central nervous system malignancies between infancy and young adulthood. Greater body weight also adversely affects breast cancer survival. These findings are complementary and support a role for positive energy balance in promoting human carcinogenesis. Potential mechanisms are discussed.

Effect of sampling site on fatty acid composition of human breast adipose tissue

The effect of sampling site and proximity of malignant tumor on the relative fatty acid composition of human breast adipose tissue was studied in 10 cases of breast cancer. The four anatomic quadrants of breast did not statistically significantly differ from each other in relation to any of the 30 fatty acids studied. Proximity of the malignant tumor did not affect the relative fatty acid composition of fat when compared with more distant sampling sites. Representative samples of breast adipose tissue for fatty acid composition analysis can be obtained from tissue adjacent to the tumor.

Nutritional factors and cancers of the breast, endometrium and ovary

From an overview of epidemiological evidence on nutrition, diet and cancers of the breast, endometrium and ovary, the following indications can be drawn: Overweight and obesity are causally related to endometrial and post-menopausal breast cancer, and may account for as much as one third of the cases of endometrial and one tenth of breast cancer in Europe. It is not known whether obesity or overweight early in life has any role on breast cancer risk, nor whether obesity influences ovarian carcinogenesis. Overweight tends to be associated with an unfavourable prognosis for breast cancer. Despite extensive research, the available knowledge on diet and breast cancer is largely inconsistent, and the results from ecological and individual-based studies are contradictory in relation to fat, proteins, total energy, alcohol, etc. There are only scanty data on diet and endometrial or ovarian cancer, which tend to suggest role for fat (or animal fat) in the risk of these neoplasms. The evidence on diet and breast, ovarian and endometrial carcinogenesis is still too scanty or inconsistent to be of any practical preventive value. Thus, the only clear indication for prevention is that a reduction of overweight would avoid a substantial number of cases of endometrial and post-menopausal breast cancer.

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.

Reproductive endocrinologic alterations in female asymptomatic obesity

Excess body fat has been clearly associated with an increased risk of oligo-ovulation and endometrial/breast carcinoma. The connection has been assumed to lie within derangements of the metabolic/endocrine compartments, particularly of estrogens and androgens. To differentiate the effect of obesity from its related disease process, an attempt has been made to define the reproductive-endocrinologic alterations encountered in otherwise asymptomatic obese women. Androgen metabolism is accelerated in obesity. It is not clear whether the increased clearance precedes or follows the accelerated production of androgens. A servocontrol mechanism appears to be operative in these asymptomatic individuals, maintaining plasma steroid levels normal. The unbound fraction of T may be somewhat increased in overweight women with predominantly upper body fat deposition. The increased clearance of androgen may arise from an obesity-related depression in SHBG concentration (e.g., for T, E2, delta 5-diol, etc.). Adipose tissue, by virtue of the lipid solubility of most of these steroids, concentrates androgens, estrogens, and progesterone. This steroid sequestration not only contributes to the obesity-related increase in androgen clearance but also leads to an extremely enlarged total body steroid pool. Fat tissue sequestration also increases the concentration of androgens in the vicinity of adipose stromal cells, possibly encouraging their aromatization. Adipose tissue also has a moderate degree of 17-hydroxysteroid dehydrogenase activity, which appears to stimulate the conversion of A to T. Finally, alterations in peripheral and hepatic conjugation and an accelerated urinary excretion may contribute to the elevated clearance of androgens. The accelerated PR of androgens may simply result as compensation for the elevated MCR in obesity. Nonetheless, evidence of alteration(s) in adrenocortical steroidogenesis has been presented suggesting a selective obesity-related enhancement in adrenal androgen secretion. These remain to be confirmed. Nonetheless, adrenocortical abnormalities may arise secondary to the influence of other circulating and intra-adrenal factors, including insulin, prolactin, estrogens, and androgens. It is not known whether the accelerated androgen metabolism or the aberrant adrenal steroidogenesis improve with weight reduction. Excess body fat increases androgen aromatization which, together with an obesity-related decrease in SHBG, is associated with mildly elevated levels of E1 and free E2 in postmenopausal women. Although premenopausal obese individuals have the same tendency, the far greater ovarian estrogen secretion overshadows any differences. The bulk of aromatization activity in fat lies in the stromal comportment. The major substrate for peripheral estrogen production is A. Testosterone also contributes to the estrogen pool via its conversion to E2.(ABSTRACT TRUNCATED AT 400 WORDS)

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.

Dietary fat and breast cancer: case-control and cohort studies

An increased risk of breast cancer in relation to a high-fat diet has been reported in several case-control studies and one cohort study conducted in different parts of the world. Most of these studies provide data on the consumption of food groups high in animal fats, e.g., meats and dairy products. Studies reporting on the amount of fat constituents consumed, adjusted or unadjusted for total caloric intake, more frequently have shown no positive association. The latter studies are not all limited to countries such as the United States with an overall high dietary fat intake; one was reported from Japan where the traditional low-fat diet is giving way to more Western-style foods, resulting in greater dietary heterogeneity for the population. The hypothesis that dietary fat causes breast cancer has been seriously weakened by the recent negative reports from two U.S. cohort studies, employing well-recognized dietary assessment strategies and multivariable analytic methods. Still, the possibility exists that specific fat constituents either naturally present or produced during the food preparation process, or fats in the presence (or absence) of other foodstuffs could alter breast cancer risk. Different kinds of studies providing information on the biochemistry and biology of fats consumed by humans would help to give focus to future epidemiological studies.

Fish consumption and breast cancer risk: an ecological study

There is experimental evidence that fish oils protect against mammary carcinogens in animals. However, there has been little investigation of the possible relevance of this finding to breast cancer in humans. We compared breast cancer incidence and mortality rates with estimates of the consumption of fish and other foods and nutrients in the countries for which reliable data are available. The results showed an inverse association between percent calories from fish and breast cancer rates that was consistent with a protective effect. This analysis confirmed the finding of others that dietary fat is strongly associated with international variation in breast cancer rates. It also showed that of the dietary components considered, percent calories from fish was the factor most strongly correlated with breast cancer rates after statistical adjustment for dietary fat intake. This result is therefore in accord with animal experimental data and suggests that the omega-3 fatty acids contained in certain fish may protect against breast cancer.

Dietary factors related to physical fitness among navy shipboard men

Abstract This study examines the relationship between habitual dietary practices and performance on the physical readiness test required of active duty Navy personnel. Participants were 1,013 men (mean age = 26.2 years) stationed aboard nine Navy ships. The men completed a self-report survey of lifestyle and dietary habits and were evaluated on four tests of physical fitness: 1.5-mile Run, Sit-ups, Sit-reach, and Percent Body Fat. A standardized Overall Fitness score was also computed for each person. Results indicated that the participants tended to skip breakfast, ingest moderate amounts of caffeine, and favor a high-fat, low-fiber diet. Fitness scores were associated with a number of dietary variables, including caffeine intake, between-meal snacking, and overeating (all negatively related to fitness, p <.01), and having a general "nutrition orientation" (positively related to fitness, p <.001). The relationships were confounded by the influence of age, exercise, and smoking, but even after controlling for these, diet was a significant predictor of fitness (p <.001).

Progress in understanding breast cancer: epidemiological and biological interactions

Little progress has been made recently in our understanding of the epidemiology of breast cancer. While results from epidemiologic studies regarding reproductive factors remain fairly reproducible from one study to another, other associations such as that between breast cancer risk and dietary fat intake, although biologically plausible, are not consistently found in direct study of humans, while yet other associations, which appear less plausible biologically, become stronger (such as the increased risk associated with modest levels of alcohol consumption). In this paper we attempt to review the epidemiology and biology of breast cancer jointly and describe possible mechanisms of breast cancer induction, the cellular composition of the breast, the epidemiology of breast cancer, and salient biological features, and attempt to reconcile the biology and epidemiology. It becomes obvious that future progress depends on better biological thinking by epidemiologists, and vice-versa. Areas of further research are suggested and discussed, concluding that the ability to measure diet with greater precision could have an important role to play in clarifying our understanding of breast cancer.

Does family history of breast cancer improve survival among patients with breast cancer?

Overall cancer mortality to December 1985 among 291 patients whose breast cancer was diagnosed between 1971 and 1974 and who were interviewed shortly after diagnosis was 39.9% (116 deaths). In this study population a positive maternal family history was strongly associated with breast cancer: The odds ratio for patients versus controls of having a mother with breast cancer was 3.32 (95% confidence limits 1.64 and 6.72); the odds ratio of having a mother, sister, or maternal aunt with breast cancer was 1.92 (95% confidence limits 1.27 and 2.91). However, family history was not associated with stage at diagnosis, which is the most important survival factor (53.6% of patients with a family history and 51.7% without were at a local stage at diagnosis). Survival was better, although not significantly so, among women with maternal relatives with breast cancer. The relative risk of dying of cancer, adjusted for confounding factors, was 1.40 for women without versus with a family history; the difference in survival was not statistically significant.

Factors related to late menopause and early menarche as risk factors for breast cancer

To investigate underlying factors of late menopause and early menarche which are regarded as risk factors for breast cancer, we analyzed the relationships between ages at menarche and menopause, and other environmental and physical factors using the data of a population-based survey conducted in Aichi Prefecture, Japan. The analysis on menopause was based on 3,148 women aged 55 or more and the analysis on menarche was based on 16,392 women aged 40 or more. These subjects were grouped into three groups (early, average and late groups) according to their ages at menopause and menarche. Women with late menopause had larger height, weight and body mass index and included more professional, administrative and office workers, more daily fish & shellfish consumers and more women with colorectal cancer history of the mother and less current smokers. Women with early menarche also had larger height, weight and body mass index and more residence in a metropolitan area and consumed more bread, meats, fish & shellfish, vegetables, fruits, milk and black tea and less rice, miso soup and pickles. In a multiple regression analysis, occupation, weight, daily or occasional drinking and daily intake of fish & shellfish were positively and smoking was inversely associated with late menopause, while residence in a metropolitan area, weight and daily intakes of bread, milk and green-yellow vegetables were positively associated with early menarche. These results suggest the importance of underlying factors of early menarche and late menopause in the etiology and prevention of breast cancer.

The problem of profound mismeasurement and the power of epidemiological studies of diet and cancer

Ecological associations of fat intake with breast cancer incidence have not, in general, been corroborated by individual-based epidemiological studies. Profound mismeasurement, which, in these studies, probably typifies measures of dietary exposures in general and of fat in particular may, in part, explain this lack of agreement. To demonstrate the way in which error masks effects, we studied the impact of extreme mismeasurement in analysis of strong or moderate underlying associations using computer-simulated, case-control studies (300 cases, 300 controls). Severe error causes the mean and median odds ratios to be biased toward unity, tests for trend and upper category odds ratios to be often not significant, and lower category odds ratios frequently to exceed higher exposure ones. Important risk relationships can be concealed, despite careful design and analysis if there is substantial mismeasurement of exposure.

Breast cancer risk in relation to serum cholesterol, serum beta-lipoprotein, height, weight, and blood pressure

The relation between breast cancer risk and serum levels of cholesterol and beta-lipoprotein (BLP), height, weight, Quetelet's index and blood pressure was studied in a cohort of 46,570 Swedish women less than 75 years of age. The cohort was examined between 1963 and 1965 and followed up in the Swedish Cancer Registry until 1983. During this period 1,182 cases of breast cancer were reported. Of those, 196 were reported among women less than 50 years of age. Statistically significant positive associations were observed between height, weight, and systolic blood pressure and breast cancer risk. No clear trend in cancer risk related to serum cholesterol or BLP was seen in the total material. In a stepwise Cox multiple regression analysis only the associations with height and blood pressure remained significant. Among women, having their cancer diagnosed before the age of 50, higher Quetelet's index was associated with a lower cancer risk, whereas a positive correlation was seen among women greater than or equal to 50 years. In the group of younger women a high BLP level was associated with an increased risk of breast cancer. This relation became even stronger when studied in a multivariate analysis, which also showed a negative correlation between serum cholesterol and cancer risk.

Correspondence between perceptions of change in diet and 15-year change in diet reports in the Tecumseh Diet Methodology Study

As part of an effort to assess the most reliable method of obtaining information about long-term dietary intake, a study was conducted of the correspondence between perception of change in diet and measured change in reported diet from 1967 to 1982. Respondents were 1,201 men and women participants in the Tecumseh Food Frequency Study of 1967-1969 who were 45-64 years of age in 1982-1983, the time of the Diet Methodology Study. Perceptions of change were obtained by asking respondents directly if they thought they currently ate each of 12 food groups more often, less often, or as often as they did during the year of their earlier interview. Measured change was obtained by subtracting each respondent's baseline frequency for each of the 12 food groups from his or her current frequency. For 10 of the 12 food groups, correspondence was found between perception of change and measured change; fats and oils added at the table and meat were the exceptions. Significant linear relationships were found between perceptions and measured change for all food groups except fats and oils. However, greatly varying coefficients were associated with terms such as more often or as often as before, thereby limiting the potential utility of combining perceptions of change with current frequencies to obtain a reliable measure of baseline frequencies.

The relationship of dietary intake and serum levels of retinol and beta-carotene with breast cancer. Results of a case-control study

The possible association between the risk of breast cancer, blood level, and dietary intake of preformed Vitamin A (retinol) and beta-carotene was investigated in a case-control study carried out from May 1982 to June 1985. The patients studied were 214 previously untreated individuals with T1-2, N0-1, M0 breast cancer admitted to the National Cancer Institute of Milan and 215 controls admitted for conditions other than neoplastic or metabolic disorders. Both cases and controls were selected from an age group ranging from 30 to 65 years old. Plasma levels of retinol and beta-carotene were tested from blood samples drawn during the first day after admission to the hospital. A questionnaire about diet was used to estimate the mean intake of 69 food items from which a daily dietary index of retinol and beta-carotene intake was computed. Information relating to the woman's history, socioeconomic status, and known risk factors for breast cancer was also collected. No association was found between beta-carotene (in the diet or blood) or dietary retinol and the risk of breast cancer. As for blood retinol, our data show a significant trend of increasing risk with higher levels; multivariate relative risk for subsequent serum levels based on the control quintiles, are 1, 1.5, 1.8, 1.7; (test for linear trend: chi-square = 8.26). Thus, these findings, together with the results of other studies, suggest that retinol and beta-carotene are unlikely to be related to the risk of breast cancer.

Risk of breast cancer among Greek women in relation to nutrient intake

A case-control study of the role of diet in the cause of breast cancer was conducted in Athens, Greece. The case series consisted of 120 consecutive patients with histologically confirmed breast cancer admitted to either of two teaching hospitals over a 12-month period. The controls were 120 patients admitted to a teaching hospital for trauma and orthopedic conditions during the same period. Dietary histories concerning the frequency of consumption of 120 foods and drinks were obtained by interview. Nutrient intakes for individuals were estimated by multiplying the nutrient content of a selected typical portion size for each specified food item by the frequency that the food was used per month and summing these estimates for all food items. Cases reported significantly less frequent consumption of vitamin A after controlling for total caloric intake, potential external confounding variables and other nutrients associated with breast cancer risk. The odds ratio estimated for consumption of vitamin A equal to the value of the 90th centile versus consumption equal to the value of the 10th centile was 0.46 with 90% confidence limits 0.26-0.82. There was no evidence that high intake of dietary fat increases the risk of breast cancer.

Serum lipids and lipoprotein disorders in cancer patients

Total serum cholesterol, free and esterified cholesterol, high-density lipoprotein (HDL) and low-density lipoprotein (LDL) cholesterol, serum triglycerides and serum lipoproteins were measured in 103 consecutive cancer patients (60 men and 43 women; mean age, 56 years) and 100 age-matched noncancer inpatients. Cancer patients as a group demonstrated significantly lower total cholesterol, esterified cholesterol and LDL cholesterol, compared with noncancer patients. Breast cancer proved to be an exception associated with increased serum total cholesterol, free cholesterol, LDL cholesterol, and triglycerides. a-lipoproteins were constantly increased in cancer patients whereas no differences were found in the other lipoprotein fractions. Finally, the observed overall incidence of hyperlipidemia in cancer patients (23/103) was not significantly different from the controls (29/100).

Cross-cultural correlations of childhood growth and adult breast cancer

International differences in breast cancer incidence and mortality, and studies on Japanese migrants to the United States, point to the importance of environmental factors, including diet and nutrition, in the etiology of breast cancer. Some studies have suggested that dietary patterns in early life are important to the long-term risk of breast cancer. Given that human growth is partially a function of early dietary intake, cross-cultural correlations between breast cancer rates and anthropometric variables measured at different times in childhood provide additional information about the association of early nutrition and cancer. In this study, the associations between food consumption and anthropometric variables, and childhood growth patterns (attained size at age) and adult breast cancer rates, were considered. Data from cross-sectional growth studies conducted during the years 1956-1971 on children aged 6-18 years were obtained for age-specific stature, sitting height, weight, triceps skinfold thickness, arm and chest circumferences, and biacromial and biiliac diameters. National food consumption data were obtained from the United Nations Food and Agriculture Organization (FAO) and socioeconomic status indicators from the United Nations Children's Fund (UNICEF). Cancer incidence data for the years 1972-1977 were obtained from regional cancer registries reported by the International Agency for Research on Cancer (IARC), and mortality data for 1978 were obtained from national cancer registries around the world. Significant correlations were seen between national food consumption data and childhood growth (attained size at age); between cancer incidence and age-specific stature (r = 0.68), weight (r = 0.59), triceps skinfold thickness (r = 0.78), and biacromial width (r = 0.84); and between mortality and age-specific stature (r = 0.77), weight (r = 0.75), and biacromial width (r = 0.78). In general, the correlation coefficients of the observed anthropometric variables with breast cancer increase with increasing age and become highly significant at ages 13-14 years, reflecting cumulative childhood nutritional intake.

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?