The search for the causes of breast and colon cancer

Calcium and magnesium in drinking water and risk of death from rectal cancer

The possible association between the risk of rectal cancer and the levels of calcium and magnesium in drinking water from municipal supplies was investigated in a matched case-control study in Taiwan. All eligible rectal-cancer deaths (986 cases) of Taiwan residents from 1990 through 1994 were compared with a sample of deaths from other causes (986 controls), and the levels of calcium and magnesium in the drinking water of these residents were determined. Data on calcium and magnesium levels in drinking water throughout Taiwan were obtained from the Taiwan Water Supply Corporation (TWSC). The control group consisted of people who died from other causes, and the controls were pair-matched to the cases by gender, year of birth and year of death. Compared with those with calcium levels below 22.0 mg/liter, the adjusted odd ratios (95% confidence interval) were 0.72 (0.53-0.98) for the group with water calcium levels between 22.0 and 40.8 mg/liter and 0.63 (0.45-0.87) for the group with calcium levels of 40.9 mg/liter or more. The adjusted odd ratios were not statistically significant for the relationship between magnesium levels in drinking water and rectal cancer. The results of the present study show that there may be a significant protective effect of calcium intake from drinking water on the risk of rectal cancer.

Whole grain food intake and cancer risk

The relationship between frequency of consumption of whole grain food and risk of selected neoplasms has been analysed using data from an integrated series of case-control studies conducted in northern Italy between 1983 and 1996. The overall dataset included the following incident, histologically confirmed neoplasms: oral cavity and pharynx 181, oesophagus 316, stomach 745, colon 828, rectum 498, liver 428, gallbladder 60, pancreas 362, larynx 242, breast 3,412, endometrium 750, ovary 971, prostate 127, bladder 431, kidney 190, thyroid 208, Hodgkin's disease 80, non-Hodgkin's lymphomas 200, multiple myelomas 120. Controls were 7,990 patients admitted to hospital for acute, non-neoplastic conditions, unrelated to long-term modifications in diet and not likely to have been caused by tobacco or alcohol use. Odds ratios (OR) for subsequent scores (never/occasional/frequent) of whole grain food consumption were derived after allowance for age, sex, education, smoking, alcohol intake and body mass index. High intake of whole grain foods consistently reduced risk of neoplasm at all sites, except thyroid. The ORs for the highest category of consumption were 0.2-0.3 for upper digestive and respiratory tract neoplasms, 0.5 for stomach, colon and gallbladder, 0.7 for rectum, 0.6 for liver, 0.8 for pancreas and prostate, 0.9 for breast and endometrium, 0.6 for ovary, 0.4 for bladder and kidney, 1.3 for thyroid and around 0.5 for lymphomas and myeloma. The tests for trend in risks were significant for all neoplasms, except pancreas, endometrium, Hodgkin's disease and multiple myeloma. No significant heterogeneity was found across strata of age at diagnosis, sex, education, smoking habit, alcohol intake and body mass index. Thus, even in the absence of a univocal and satisfactory biological interpretation, the consistency of the patterns observed indicate that, in this population, higher frequency of whole grain food intake is an indicator of reduced risk of several neoplasms.

Cancer mortality in Europe: effects of age, cohort of birth and period of death

Death certification data for 19 cancers or groups of cancers, plus total cancer mortality, in 16 major European countries were analysed using a log-linear Poisson model with arbitrary constraints on the parameters to disentangle the effects of age, birth cohort and period of death. Three major patterns emerged including: first, the prominent role of cohort of birth in defining trends in mortality from most cancer sites (except testis or Hodgkin's disease, where newer treatments had a major period of death effect); and second, the major role of lung and other tobacco-related neoplasm epidemics in determining the diverging pattern of cancer mortality, for each sex and in various European countries and geographic areas. In most countries, the peak male cohort values were reached for generations born between 1900 and 1930. This was observed in women only for Denmark and the U.K., i.e. the two countries where lung and other tobacco-related neoplasm epidemics had already reached appreciable levels. This confirms the importance of cigarette smoking in subsequent generations as a major cause of cancer deaths in Europe. Further, there is a persistent rise in several cancer rates, again chiefly on a cohort basis, in Eastern Europe, which calls for urgent intervention to control the cancer burden in these countries.

Aberrant nuclear factor-kappaB/Rel expression and the pathogenesis of breast cancer

Expression of nuclear factor-kappaB (NF-kappaB)/Rel transcription factors has recently been found to promote cell survival, inhibiting the induction of apoptosis. In most cells other than B lymphocytes, NF-kappaB/Rel is inactive, sequestered in the cytoplasm. For example, nuclear extracts from two human untransformed breast epithelial cell lines expressed only very low levels of NF-kappaB. Unexpectedly, nuclear extracts from two human breast tumor cell lines displayed significant levels of NF-kappaB/Rel. Direct inhibition of this NF-kappaB/ Rel activity in breast cancer cells induced apoptosis. High levels of NF-kappaB/Rel binding were also observed in carcinogen-induced primary rat mammary tumors, whereas only expectedly low levels were seen in normal rat mammary glands. Furthermore, multiple human breast cancer specimens contained significant levels of nuclear NF-kappaB/Rel subunits. Thus, aberrant nuclear expression of NF-kappaB/Rel is associated with breast cancer. Given the role of NF-kappaB/Rel factors in cell survival, this aberrant activity may play a role in tumor progression, and represents a possible therapeutic target in the treatment of these tumors.

Pilot study of free and conjugated urinary mutagenicity during consumption of pan-fried meats: possible modulation by cruciferous vegetables, glutathione S-transferase-M1, and N-acetyltransferase-2

Epidemiological and experimental evidence indicates that consumption of fried meats in conjunction with certain genotypes of phase I and II metabolism genes poses an elevated risk for colorectal cancer. Parallel to this, the consumption of cruciferous vegetables is associated with a reduced risk of colon cancer. Therefore, we designed a 6-week pilot feeding study to evaluate the effect of these variables on urinary mutagenicity, which is a biomarker associated with fried-meat consumption. Eight subjects were fed fried meats daily for six weeks; four ate cruciferous vegetables, and four ate non-cruciferous vegetables. Urinary mutagenicity was evaluated in the presence of S9 in strain YG1024 of Salmonella, which is a frameshift strain that overproduces acetyltransferase. C18/methanol extracts of 24-h urines collected once each week were tested unhydrolyzed (free mutagenicity) and hydrolyzed (total mutagenicity); the difference between the two was the conjugated mutagenicity. Although not significant, the levels of conjugated urinary mutagenicity doubled among crucifera consumers and decreased to 30% of the initial levels among non-crucifera consumers, suggesting the possibility that crucifera may enhance the level of conjugated urinary mutagenicity resulting from consumption of fried meats. Such an effect would be consistent with the documented ability of cruciferous vegetables to induce phase II enzymes. The NAT2 rapid phenotype was significantly associated with approximately 2-fold increases in conjugated (p = 0.05) and total (p = 0.004) urinary mutagenicity relative to NAT2 slow subjects, consistent with the elevated risk confirmed by the NAT2 rapid phenotype for colorectal cancer among meat consumers. An approximately 2-fold increase in urinary mutagenicity among the GSTM1- subjects relative to the GSTM1+ subjects approached significance for free (p = 0.18) and total (p = 0.13) urinary mutagenicity. This is the first report on (a) the mutagenicity of hydrolyzed urine, which was consistently more mutagenic than unhydrolyzed urine; (b) the potential enhancement of conjugated urinary mutagenicity by crucifera; and (c) the association of the rapid NAT2 and possibly the GSTM1- phenotype with elevated levels of fried meat-associated urinary mutagenicity.

Prospective study of diet and female colorectal cancer: the New York University Women's Health Study

The relation between diet and female colorectal cancer was analyzed in a prospective study of 14,727 women aged 34-65 years, who were enrolled at mammographic screening clinics in New York and Florida from 1985 to 1991. They were followed through the end of 1994 (average 7.1 yrs) by a combination of direct contact through mail and telephone and record linkages with regional tumor registries, resulting in 100 incident cases of colorectal cancer. There was no overall positive or inverse association of colorectal cancer risk with intakes of total calories, total or subclasses of fat, carbohydrate, or dietary fiber, whereas there was an inverse association with total protein. Among major food groups, there was a progressive decline in risk of colorectal cancer with increasing intake of fish and shellfish (relative risk for 4th vs. 1st quartile = 0.49, 95% confidence interval = 0.27-0.89). A similar inverse association was also observed for consumption of dairy products, and this association was explained mainly by calcium, not by other nutrients, such as fat or protein. The results of the present study indicated that certain dietary components of fish or dairy products may protect against colorectal cancer, whereas the relations with red meat or total fat remained unclear.

Calcium and magnesium in drinking water and risk of death from colon cancer

The possible association between the risk of colon cancer and the levels of calcium and magnesium in drinking water from municipal supplies was investigated in a matched case-control study in Taiwan. All eligible colon cancer deaths (1714 cases) of Taiwan residents from 1989 through 1993 were compared with deaths from other causes (1714 controls), and the levels of calcium and magnesium in drinking water of these residents were determined. Data on calcium and magnesium levels in drinking water throughout Taiwan were obtained from the Taiwan Water Supply Corporation. The control group consisted of people who died from other causes and the controls were pair-matched to the cases by sex, year-of-birth, and year-of-death. The adjusted odd ratios (95% confidence interval) were 0.79 (0.64-0.98) for the group with water calcium levels between 24.4 and 42.3 mg/liter and 0.58 (0.47-0.73) for the group with calcium levels of 42.4 mg/liter or more. The adjusted odd ratios were not statistically significant for the relationship between magnesium levels in drinking water and colon cancer. The results of the present study show that there is a significant protective effect of calcium intake from drinking water against colon cancer.

Family history of cancer and risk of breast cancer

The relationship between breast cancer risk and family history of cancer in first-degree relatives was investigated using data from a multicentric case-control study conducted in Italy between June 1991 and April 1994 on 2,569 women aged less than 75 years, with histologically confirmed incident breast cancer, and 2,588 control women admitted to hospital for acute, non-neoplastic, non-gynaecological conditions. Relative to women with no history, those with a family history of breast cancer had an odds ratio (OR) of 2.4 [95% confidence interval (CI) 1.9-3.0], and those with family history of intestinal cancer had an OR of 1.3 (95% CI 1.0-1.7). No significant relations emerged between breast cancer risk and family history of prostate (OR 1.1), ovarian (OR 1.3), cervical or endometrial (OR 1.2) or other cancers, except gallbladder (OR 8.6). The OR for family history of any type of cancer except breast cancer was 1.1. For family history of breast cancer the ORs were similar across strata of age of the proband, being 2.4 below age 45, 2.2 at age 45-59 and 2.7 above age 60, and whether the relative affected was the mother, sister(s) or both, while the risk appeared higher if the age at onset of breast cancer in the relative was lower than 40 years (OR 3.5), rather than higher (OR 2.2). Thus, our results, based on the investigation of all neoplasms in first-degree relatives, confirm that breast cancer risk is increased in women with a family history of breast cancer, while there was no material association with family history of cancer in general, excluding breast cancer.

Nutritional factors and colon carcinoma: a case-control study involving French Canadians in Montréal, Quebec, Canada

BACKGROUND

In a population-based case-control study of colon carcinoma and nutrition involving the francophone community in Greater Montreal, a total of 402 cases (200 males and 202 females) and 668 controls (239 males and 429 females) were interviewed.

METHODS

Cases from 1989-1993 were identified through the admission offices of 5 major francophone teaching hospitals in Montreal and were ages 35-79 years. Controls matched by age, place of residence, and language were selected by a modified random digit dialing method. Information on dietary intake was collected with a quantitative food frequency questionnaire.

RESULTS

No associations were evident between colon carcinoma and total energy, protein, or carbohydrate consumption, whereas a suggestive inverse association was found with total fat intake, with an odds ratio (OR) of 0.78 (P = 0.0637), and with saturated fat intake as well (OR = 0.71, P = 0.0893). A strongly significant inverse association was found with dietary fiber (OR = 0.50, P = 0.0018). The strongest inverse association concerning fiber was found with fiber from vegetable sources (OR = 0.57, P = 0.0096), and a suggestive (although nonsignificant) inverse association (OR = 0.74, P = 0.0687) was found with fiber from fruits. Calcium was inversely associated with risk (OR = 0.69, P = 0.0411), as was dietary intake of vitamin A (OR = 0.67, P = 0.0162), retinol, (OR = 0.069, P = 0.0409), vitamin E (OR = 0.53, P = 0.0028), and alphatocopherol (OR = 0.63, P = 0.0256). Although there was no association demonstrated between dietary beta-carotene intake and risk, a suggestive (although nonsignificant) inverse association with intake of other types of carotene was observed (OR = 0.76, P = 0.0740). No association was found between intake of other nutrients investigated in this study and risk of colon carcinoma.

CONCLUSIONS

There is strong evidence from epidemiologic studies that high intake of fat and meat are risk factors for colorectal carcinoma in humans, whereas high intake of vegetable and fruit are inversely associated with risk of colon carcinoma. The findings from this study are in agreement with this observation.

Microsatellite instability in breast cancer

BACKGROUND

Microsatellites are short repetitive nucleotide sequences that, through mutation, can undergo either expansion or contraction. This novel mutational mechanism known as microsatellite instability may play a role in carcinogenesis. We investigated the incidence of microsatellite instability in a series of primary breast carcinoma surgical specimens.

METHODS

Using polymerase chain reaction techniques followed by polyacrylamide/urea gel electrophoresis, we analyzed 46 pairs of normal and primary breast tumor samples at seven different microsatellite loci, five of which were located on chromosome 17.

RESULTS

Thirteen of our 46 tumors (28.2%) demonstrated microsatellite instability. Five tumors (10.8%) were unstable at two or more loci, and of those, four (8.7%) were unstable at different loci on different chromosomes. An additional five tumors demonstrated loss of heterozygosity alone when compared with their normal counterparts.

CONCLUSIONS

These findings indicate that microsatellite instability is present in primary breast cancer populations and, although the mechanism of action has yet to be elucidated, may play a role in breast carcinogenesis.

Diet, anthropometry and breast cancer: integration of experimental and epidemiologic approaches

The interrelation ships of dietary fat and energy, growth rates and anthropometry, and breast carcinogenesis have been examined by a diverse array of approaches throughout the last 50 y as new investigative tools have been developed by laboratory scientists and epidemiologists. A consensus among investigators has not emerged, however, and dietary recommendations for breast cancer prevention have not been clearly formulated or effectively communicated to the public. Indeed, the gap between those investigators utilizing laboratory-based approaches and those using epidemiologic models has expanded in recent years. Cancer epidemiologists have become increasingly skeptical that results derived form laboratory animal models of breast carcinogenesis and in vitro systems are directly applicable to human breast cancer risk. Concurrently, laboratory scientists have questioned the ability of epidemiological tools to accurately measure dietary intake and relevant biomarkers and to account for a diverse array of potentially confounding environmental and genetic factors characteristic of human populations under study. These polarized views are reinforced by a failure of investigators using diverse approaches to interact, integrate their skills and resources, develop novel hypotheses, and propose solutions using both laboratory and epidemiologic techniques. Therefore, the objectives of this symposium are to summarize experimental and epidemiologic knowledge, foster communication and collaboration, and attempt to identify appropriate studies to bridge the gaps in our knowledge concerning dietary lipid and energy, anthropometrics, and breast cancer risk.

Dietary fat influences on polyp phenotype in multiple intestinal neoplasia mice

Significant differences in colon cancer incidence worldwide have led to the hypothesis that this variation can be explained largely by environmental, notably dietary influences. Although a positive correlation between dietary fat intake and incidence is suggested from some human epidemiological and rodent carcinogenesis studies, a direct association remains contentious. Using a spontaneous mouse tumor model of multiple intestinal neoplasia, we demonstrate that there is a generalized increase in tumor counts, in both the large and small bowel with higher dietary fat [standard (3%) fat versus high (15%) fat diet (mean +/- SD) 1.59 +/- 1.46 vs. 3.85 +/- 2.37 P < 0.001 and 21.36 +/- 7.4 vs. 31.3 +/- 9.7, respectively, P < 0.001]. Increasing dietary fat also increases polyp size in the small bowel. These changes appear independent of total calorific intake as assessed by body weights. Halving the crude fiber intake together with an increase in dietary fat from 3% to 10% did not have as marked an effect on tumor counts as an increase of fat alone to 15%, which also decreased survival (P < 0.05). These results demonstrate that increasing dietary fat intake from weaning can have a significant adverse effect on polyp numbers in mice genetically predisposed to intestinal tumor development. A further understanding of the biology of this interaction may provide novel strategies aimed at both colonic polyp prevention and treatment.

Mechanisms of the intestinal effects of dietary fats and milk products on colon carcinogenesis

Dietary fat may promote colon cancer by increasing fatty acids (FA) and secondary bile acids (BA) in the colonic lumen. These cytotoxic surfactants can damage colonic epithelial cells and thus induce a compensatory hyperproliferation of crypt cells. Our studies show that the hyperproliferative effect of type and amount of dietary fat is not simply due to changes in colonic FA and BA. This indicates that an additional, at present unknown, cytotoxic factor is involved. The hyperproliferative effect of dietary fat is inversely related to the amount of calcium in the diet. In rat and man, dietary calcium precipitates colonic cytotoxic surfactants and thus inhibits luminal cytotoxicity. These inhibitory effects on metabolic risk factors suggest a preventive effect of dietary calcium on colon carcinogenesis.

Diet and premenopausal bilateral breast cancer: a case-control study

We investigated associations between diet and premenopausal bilateral breast cancer in a familial matched case-control study. We studied 140 cases from population-based registries in Los Angeles County (California) and Connecticut, and from the major hospitals in the southern parts of the Province of Quebec. Unaffected sisters of the cases served as matched controls (222 total). Dietary intake were assessed with a food frequency questionnaire. Total fat, monounsaturated fat, polyunsaturated fat, oleic acid, and linoleic acid intake was inversely associated with premenopausal bilateral breast cancer risk. Consumption of carbohydrates (and sweetened beverages) was associated with an increased risk. We observed no associations for dietary fiber, antioxidants, or major food groupings, but we did observe inverse associations for intake of low fat dairy products and tofu. These findings suggest that monounsaturated and polyunsaturated fats, as well as soy foods, might reduce the risk of premenopausal bilateral breast cancer.

Risk factors for colorectal cancer in subjects with family history of the disease

The relationship between lifestyle factors, past medical conditions, daily meal frequency, diet and the risk of 'familial' colorectal cancer has been analysed using data from a case-control study conducted in northern Italy. A total of 1584 colorectal cancer patients and 2879 control subjects were admitted to a network of hospitals in the Greater Milan area and the Pordenone province. The subjects included for analysis were the 112 cases and the 108 control subjects who reported a family history of colorectal cancer in first-degree relatives. Colorectal cancer cases and control subjects with family history were similarly distributed according to sex, age, marital status, years of schooling and social class. Familial colorectal cancer was associated with meal frequency, medical history of diabetes (relative risk, RR = 4.6) and cholelithiasis (RR = 5.2). Significant positive trends of increasing risk with more frequent consumption were observed for pasta (RR = 2.5, for the highest vs the lowest intake tertile), pastries (RR = 2.4), red meat (RR = 2.9), canned meat (RR = 1.9), cheese (RR = 3.5) and butter (RR = 1.9). Significant inverse associations and trends in risk were observed for consumption of poultry (RR = 0.4), tomatoes (RR = 0.2), peppers (RR = 0.3) and lettuce (RR = 0.3). Significant inverse trends in risk with increasing consumption for beta-carotene and ascorbic acid were observed (RR = 0.5 and 0.4 respectively, highest vs lowest intake tertile). These results suggest that risk factors for subjects with a family history of colorectal cancer in first-degree relatives are not appreciably different from recognized risk factors of the disease in the general population.

Enhancing effect of polysaccharides from an edible brown alga, Hijikia fusiforme (Hijiki), on release of tumor necrosis factor-alpha from macrophages of endotoxin-nonresponder C3H/HeJ mice

An enhancing activity for the release of tumor necrosis factor-alpha from macrophages of C3H/HeJ mice was detected in the hot water-soluble extract of an edible brown alga, Hijikia fusiforme (Hijiki in Japanese). This activity was divided into the polysaccharide and nonpolysaccharide fractions, with the former showing much higher activity than the latter. The active components in the polysaccharide fraction were further purified by ion-exchange column chromatography and gel permeation system of high-performance liquid chromatography; they were identified as polysaccharides with apparent molecular mass of about 2,000 and 70 kDa and were designated Hijiki-derived polysaccharides I and II (HPS-I and HPS-II), respectively. They also enhanced macrophage-dependent suppression against the growth of EL-4 tumor cells in an in vitro culture experiment, with HPS-I exhibiting much higher immunologic activity than HPS-II. Furthermore, other comparative experiments confirmed that the immunoenhancing activities of polysaccharides from H. fusiforme are associated with the functions of polysaccharides themselves, but not with the artificial activity induced by contaminated endotoxins. Some biochemical properties of immunoenhancing polysaccharides were partially characterized, and the significance of this finding is discussed from the viewpoint of the protective role of edible seaweeds against carcinogenesis.

Epidemiology and risk factors for colorectal cancer

The striking geographic differences in colorectal cancer incidence and the changes in disease risk among immigrants suggest an important environmental component to colorectal cancer risk. Table 1 lists risk factors for colorectal cancer. The categories in the table are somewhat arbitrary but are designed to provide an overall semiquantitative summary of the current epidemiologic literature. Certain of the most important risk factors (e.g., age, family history) cannot be modified. Individuals at high risk might benefit from surveillance. Dietary factors appear to be among the most important determinants of colorectal cancer risk. Diet helps to explain geographic variation in disease. A diet that is high in red meat and saturated fat appears to increase risk. Vegetables, fruits, fiber, folate, and calcium may be protective. Obesity, particularly abdominal obesity, and tall stature may be risk factors. Physical activity has been repeatedly shown to reduce the risk of colorectal cancer. Postmenopausal hormone replacement therapy may also be protective. Exciting new data suggest a significantly lower risk of colorectal cancer in regular users of aspirin and NSAIDs. It is important to recognize that the use of these drugs can have adverse as well as beneficial effects, and the appropriate dose and timing are not known. Enough information is available to make recommendations to lower the risk of colorectal cancer. Reducing red meat and fat consumption; increasing fruits, vegetables, and grains; avoiding obesity; and adopting a regular program of physical activity reduce the risk of colorectal cancer. Fortunately, these modifications also decrease the risk of cardiovascular disease, an even more important cause of mortality in Western societies.

A cytochrome P4502E1 genetic polymorphism and tobacco smoking in breast cancer

Known breast-cancer risk factors account for only part of the variability in breast-cancer incidence. Tobacco smoke is not commonly considered a breast carcinogen, but many of its constituents, such as N-nitrosamines, are carcinogenic in laboratory animal studies. Herein, we assessed a cytochrome P4502E1 (CYP2E1) genetic polymorphism (a Dral restriction enzyme site in intron 6) as a risk factor for breast cancer in both premenopausal and postmenopausal women. Because N-nitrosamines are metabolically activated by CYP2E1, the risk among women smokers was investigated. Caucasian women were enrolled in a case-control study of breast cancer between 1986 and 1991. A subset of the women (219 premenopausal and 387 postmenopausal women) consented to phlebotomy. The allelic frequencies for the premenopausal women (D allele = 0.91 and C allele = 0.09) and postmenopausal women (D allele = 0.93 and C allele = 0.07) were similar to those previously reported. There was no statistically significant association between the CYP2E1 polymorphism and breast-cancer risk for premenopausal or postmenopausal women (adjusted odds ratio (OR) = 1.04, 95% confidence interval (CI) = 0.48, 2.24, and OR = 1.01, 95% CI = 0.55, 1.84, respectively). When the women were categorized as nonsmokers versus smokers (those who smoked more than one cigarette per week for more than 1 yr), premenopausal women with one or two C alleles who had a history of smoking were found to be at increased risk (unadjusted OR = 7.00, 95% CI = 0.75, 14.53, and adjusted OR = 11.09, 95% CI = 1.51, 81.41), although the number of study subjects with those genotypes was small. The small number of study subjects with a C allele precluded meaningful classification by level of smoking, but categorizing the smokers into two groups (above and below the median) also suggested an increased risk. Premenopausal women with the DD genotype and postmenopausal women with any genotype were not at increased risk. Breast-cancer risk was not related to the CYP2E1 genotype in either premenopausal nonsmokers or smokers (adjusted OR = 0.66, 95% CI = 0.20, 2.17, and OR = 2.13, 95% CI = 0.60, 7.59, respectively) or postmenopausal nonsmokers or smokers (OR = 0.90, 95% CI = 0.34, 2.35, and OR = 1.02, 95% CI = 0.46, 2.23, respectively), although the difference in the ORs for premenopausal nonsmokers and smokers suggests an increased risk for smokers. While there are limitations to this study, particularly related to the small number of subjects with the DC and CC genotypes, the study suggests that some women may be susceptible to tobacco smoke because of a CYP2E1 polymorphism. However, these results are preliminary and must be replicated.

Determinants of age at menarche as early life predictors of breast cancer risk

Age at menarche is one of the few established risk factors for breast cancer; identification of its exogenous determinants could throw light on the origins of breast cancer. We have undertaken an epidemiologic study in Greece to ascertain whether: 1) energy intake, an indicator of physical activity, is associated with later age at menarche; 2) energy-adjusted fat intake is related to earlier age at menarche; and 3) other macronutrients and anthropometric variables are predictors of age at menarche. Anthropometric, socio-economic, familiar, nutritional and lifestyle predictors of age at menarche were studied by interviewing in person 345 female students 9 to 16 years old attending 8 schools of Greater Athens. Menarche was the outcome variable in a proportional hazards model assessing the mutually adjusted incidence rate ratio by a series of predictor variables. In a complementary analysis, age at menarche was the dependent variable among menstruating girls. Consistent results were derived from the main and the complementary analysis. Increased height and body mass index accelerate the occurrence of menarche. Maternal and daughter's ages at menarche are correlated, but there is no evidence of an association with paternal education. Various measures of moderate physical activity as well as increased total energy intake were associated with a delay in age at menarche. Energy-adjusted macronutrients were not associated with age at menarche. It appears that an alteration of energy balance in early life through increased physical activity could delay age at menarche and reduce the risk for breast cancer in later life.

Nutrition chemoprevention of gastrointestinal cancers: a critical review

Various strategies utilizing specific dietary factors have been investigated for their ability to modulate the development of several cancers of the gastrointestinal tract. The effects of fat, red meat, fiber, fruits and vegetables, and alcohol on colorectal carcinogenesis have been reasonably well defined. Folate, selenium, and omega-3 fatty acids are rapidly emerging as important agents in nutrition chemoprevention, while the role of antioxidant vitamins and calcium is less certain. Although recent intervention studies from China have suggested a protective role of certain vitamins and minerals for esophageal and gastric cancers, further data from prospective randomized intervention studies are needed. Until more firm data are available, the dietary recommendations provided by the American Cancer Society and the National Cancer Institute are appropriate guidelines.

Increased incidence of cancer in first degree relatives of women with double primary carcinomas of the breast and colon

Breast and colon cancer are among the most common cancers in the developed world. Several epidemiological studies suggest that the occurrence of one of these two cancers in a woman may predispose to the development of the other. The occurrence of both forms of cancer in the same woman may be because of chance or common susceptibility. In order to determine how frequently double primary cancers have a hereditary basis, we conducted a registry based study at a single Montreal hospital. Cancer rates in first degree relatives of patients with multiple primaries were compared with provincial age standardised incidence rates and relative risks (RRs) were estimated. In first degree relatives under 45 there was a total of 15 cancers observed, compared with 3.70 expected, giving an RR of 4.05 (95% CI: 2.27-6.68). The RR for colon cancer was significantly increased among male relatives. For relatives less than 45 years old at diagnosis, the RR for colon cancer was 66.7 (95% CI: 13.8-195) (three cases observed, 0.045 expected). For all ages the RR was 5.02 (95% CI: 2.04-10.5). The RR for breast cancer was 5.92 (95% CI: 1.91-13.8) for female relatives under 45 (five cases observed, 0.845 expected) and 2.14 (95% CI: 1.07-3.83) for breast cancer at any age. These results suggest that there may be genes that predispose to both breast and colon cancer in certain people.

Worldwide trends in cancer mortality in the elderly, 1955-1992

Trends in age-standardised mortality for all cancers and 21 cancers or groups of cancers over the period 1955-1992 were analysed for 33 countries from four continents in a population aged 65-84 years. Mortality from all neoplasms in the elderly showed heterogeneous patterns in various countries and in the two sexes. Trends were generally more favourable for females than for males, reflecting essentially the earlier and more extensive impact of the lung cancer (and other tobacco-related neoplasms) epidemic in elderly males, in addition to the earlier decline of gastric cancer and a widespread decline of cervical cancer rates in females. In several countries, particularly from western Europe, but also Japan, cancer mortality trends were more favourable over the last two decades than in earlier calendar periods. Some countries of northern and central Europe (including Finland, Germany, Austria and Switzerland) showed stable or even downward trends over time for total cancer mortality in both sexes, particularly in males. This reflects the different patterns of the tobacco-related (lung) cancer epidemic in various countries, and the impact of a few other major neoplasms, including in particular the systematic downward trends in stomach cancer. In contrast, rates were moderately upwards in males in North America, and several countries of southern and eastern Europe, where cancer mortality in the elderly was comparatively low in the 1950s, showed appreciable upward trends, mostly in males. Thus, there was a generalised tendency towards a levelling of the differences in certified cancer mortality in the elderly population in various areas of the world. Although there are substantial limits and uncertainties in the reliability and validity of cancer death certification and their trends in the elderly, there is no widespread and generalised upward trend in cancer mortality, with a major exception of lung and other tobacco-related neoplasms. Furthermore, in several countries, cancer mortality trends over the last four decades have been favourable for elderly women.

Attributable risks for colorectal cancer in northern Italy

Using data from a case-control study conducted between 1985 and 1992 in northern Italy on 828 cases of colon cancer, 498 cases of rectal cancer and 2,024 controls in hospital for acute, non-neoplastic, non-digestive tract disorders, we estimated the percent population attributable risk (PAR) for colorectal cancer in relation to beta-carotene, vitamin C (as markers of a diet rich in fruit and vegetables), red meat and seasoning fat intake, daily meal frequency and family history of the disease. On the basis of multivariate odds ratios, adjusted for total calorie intake, a low intake of beta-carotene accounted for 39% of all the cases and a low intake of vitamin C for 14%. These two micronutrients together explained 43% of all colorectal cancer cases in this population. A high frequency of intake of red meat consumption explained 17% of all cases, and a high score of seasoning fats 4%. A higher daily meal frequency was responsible for 13% of the cases, and these 5 dietary factors together explained 63% of colorectal cancer cases in this population. Family history of colorectal cancer accounted for 4% of all cases. These estimates were similar for colon and rectal cancers separately, in males and females, and in younger and elderly subjects, except for seasoning fats and family history, whose PARs were apparently greater for colon cancer and at younger age. Thus, even though available dietary data were limited in several aspects, and the PAR estimates were based on somewhat arbitrary assumptions regarding the exposure distribution, about two-thirds of all colorectal cancers in this population could be explained in terms of a few risk factors or risk indicators considered. This would correspond to the avoidance of a large proportion of the over 18,000 deaths from colorectal cancer registered per year in the whole of Italy.

Can supplementary dietary fibre suppress breast cancer growth?

Case-control studies in diverse populations around the world have reported a lower risk of breast cancer in association with higher intake of dietary fibre and complex carbohydrates. Although this has not been confirmed in prospective studies in the USA, the observations have prompted the hypothesis that prolonged use of dietary fibre supplements might reduce breast cancer risk in high-incidence populations. Several possible mechanisms of action have been suggested, all involving a reduction of bioactive oestrogen levels in the blood. The various mechanisms are not necessarily mutually exclusive. First, a high-fibre diet might reduce circulating oestrogen levels by reducing the enterohepatic recirculation of oestrogen. Second, many plants and vegetables contain isoflavones and lignans capable of conversion in the bowel into weak oestrogens that may compete with oestradiol for target binding-sites. Third, a high-fibre diet is less often associated with obesity, which tends to increase availability of the biologically active 16-alpha metabolites of oestrone. Fourth, a high-fibre diet usually has a lower content of fat and a higher content of antioxidant vitamins, which may protect against breast cancer risk. Finally, diets rich in fibre and complex carbohydrates have been shown to improve insulin sensitivity, with an associated reduction in circulating oestrogen levels. Synergism between these effects offers a possible mechanism by which a high fibre intake might suppress breast cancer growth in women.

Alcohol consumption and risk of colorectal cancer in a cohort of Finnish men

We investigated the association between self-reported alcohol ingestion and colorectal cancer in a cohort of male smokers in Finland. Among 27,109 men aged 50 to 69 years, 87 colon and 53 rectal cases were diagnosed during the five to eight years of follow-up. Among drinkers, colorectal cancer risk increased with the amount of alcohol consumed (P trend = 0.01) with risk increasing by 17 percent for each drink consumed. Both beer and spirits contributed to this increased risk. Further analyses revealed that the positive association with alcohol was primarily for colon cancer (P trend = 0.01). Interestingly, risk of colorectal cancer associated with drinking (cf self-reported abstinence) changed with follow-up time, suggesting an inverse association for alcohol early in follow-up, and a positive association after about three-and-a-half years of follow-up. Follow-up time did not modify the positive association with amount of alcohol among drinkers, however. Results also indicated that beta-carotene supplementation may attenuate the effect of alcohol on colorectal cancer risk among drinkers. In conclusion, this study supports a role for alcohol in colon carcinogenesis and suggests that similar studies should evaluate carefully the effects of lifetime drinking habits and recent abstinence.

Intake of selected micronutrients and the risk of breast cancer

To investigate the relation between selected micronutrients and breast cancer risk, we conducted a case-control study of breast cancer between June 1991 and April 1994 in 6 Italian areas. The study included 2569 women admitted to the major teaching and general hospitals of the study areas with histologically confirmed incident breast cancer and 2588 control women with no history of cancer, who were admitted to hospitals in the same catchment areas for acute, non-neoplastic, nongynecological conditions unrelated to hormonal or digestive tract diseases or to long-term modifications of the diet. Dietary habits, including alcoholic beverage consumption, were investigated using a validated food frequency questionnaire, including 78 foods or food groups, several types of alcoholic beverages, some "fat intake pattern" questions and some open sections for foods consumed frequently by the subject and not reported in the questionnaire. To control for potential confounding factors, several multiple logistic regression models were used. When major correlates, energy intake and the mutual confounding effect of the various micronutrients were taken into account, beta-carotene, vitamin E and calcium showed a significant inverse association with breast cancer risk. The estimated odds ratios of the 5th quintile compared to the lowest one were 0.84 for beta-carotene, 0.75 for vitamin E and 0.81 for calcium. No significant association emerged for retinol, vitamin C, thiamin, riboflavin, iron and potassium. Our results suggest that a diet rich in several micronutrients, particularly beta-carotene, vitamin E and calcium, may be protective against breast cancer.

Synchronous metastatic breast cancer in a husband and wife

We present the first reported case of synchronous metastatic breast carcinoma in a husband and wife.

Preventing colorectal cancer

After decades of little apparent progress against colorectal cancer, we now have the means to avert many of the deaths associated with this malignancy. Earlier diagnosis, either through screening for fecal occult blood or by endoscopy, has been clearly shown to be effective in reducing mortality. There are also prospects for preventing colorectal cancer occurrence through life-style change, since epidemiological studies consistently show that a dietary pattern of high intake of fruits, vegetables, and fiber is associated with a substantially decreased risk of these tumors. A further approach to prevention is the use of pharmacologic agents. Several randomized prevention trials to assess possible preventive drugs or nutrient supplements have focused on patients treated for colorectal adenomas. These trials are feasible, but they pose important challenges in protocol design, recruitment, and patient compliance. Nonsteroidal anti-inflammatory drugs (NSAIDs), especially aspirin, currently appear to be the most promising agents for testing in future trials.

Fatty acid proportions in cholesterol esters and risk of premature death from cancer in middle aged French men

OBJECTIVE

To assess the association of proportions of fatty acids in cholesterol esters with the risk of premature death from cancer in middle aged men.

DESIGN

Prospective cohort study.

SETTING

Paris, France.

SUBJECTS

3277 working men aged 36-52 in 1981-5.

MAIN OUTCOME MEASURES

Cancer mortality during an average of 9.3 years of follow up.

RESULTS

59 men died of cancer during follow up. The age adjusted relative risks for men in the highest thirds of the distribution of the proportions of linoleic, palmitoleic, and oleic acid in cholesterol esters as compared with those in the corresponding lowest thirds were 0.16 (95% confidence interval 0.05 to 0.51), 3.39 (1.63 to 7.05), and 4.22 (1.95 to 9.12), respectively. Adjustment for and stratification by smoking, alcohol consumption, serum cholesterol concentration, and body mass index did not alter the results. At the time of examination subjects with cancer had a lower intake of polyunsaturated fats, assessed by 24 hour recall, than those without cancer (13.2 v 17.4 g/day, P < 0.01).

CONCLUSIONS

Monounsaturated and polyunsaturated fatty acids of cholesterol esters are strong biological markers that predict premature death from cancer in French men. Consistently, intake of polyunsaturated fats did not seem to increase the risk of death from cancer. The association of biological markers of dietary fat intake with incidence of and mortality from cancer should be investigated prospectively in other populations.

Diet and chemoprevention of colon polyps and colorectal cancer

Clinical trials in colorectal cancer prevention are based on carcinogenesis research and epidemiologic observations that relate certain macronutrients, micronutrients, non-nutritive factors in foods, and synthetic chemicals to colon neoplasms. These factors appear to act at various points along the putative normal mucosa --> adenomatous polyp --> cancer sequence. This gives an opportunity to develop innovative clinical trails, both in agent selection and in the use of intermediate markers. Clinical colorectal cancer prevention trials are not in progress that employ dietary fiber, a variety of vitamins and minerals and several synthetic drugs, especially the NSAIDs. Most of these trials use the adenomatous polyp as a surrogate marker for colon cancer, thereby reducing trial duration, number of subjects required and overall expense. This paper is a brief review of the basic and epidemiologic background for colorectal cancer prevention trials and their current status.

Role of protein kinase C in growth stimulation of primary mouse colonic epithelial cells

The phorbol ester, 12-O-tetradecanoylphorbol-13-acetate (160 nM) and the secondary bile acid, deoxycholic acid (50 microM) stimulated DNA synthesis in quiescent primary epithelial cells from the normal mouse colon as measured by autoradiographic analysis of [3H]thymidine incorporation. The purpose of this present study was to investigate the involvement of protein kinase C in the proliferative response of the normal colonic cells. The protein kinase C inhibitor, bisindolyl-maleimide GF 109203X, efficiently blocked the proliferative response of the cells to the phorbol ester and caused a dose-dependent decrease in the response to deoxycholic acid. While the phorbol ester-induced proliferation was unaffected by another inhibitor, H-7, the response of the cells to deoxycholic acid was blocked. Pretreatment of the cells with the phorbol ester (160 nM) for 24 h blocked the proliferative response to deoxycholic acid. Measurement of the intracellular distribution of protein kinase C activity showed a time-dependent and significant translocation of the enzyme activity from the soluble to the particulate cell fractions after exposure to 12-O-tetradecanoylphorbol-13-acetate. While exposure to the bile acid indicated a similar time-dependent translocation of the enzyme activity, the effect was not significant. The phorbol ester induced a time-dependent accumulation of c-fos mRNA and protein was measured by solution hybridization and immunocytochemistry, respectively. No effect of deoxycholic acid on c-fos expression could be observed in the present study. The data support a role for protein kinase C in the growth stimulating effect of physiological concentrations of deoxycholic acid on normal colonic epithelial cells. However, differences in the mechanisms underlying phorbol ester- and bile acid-induced proliferation are indicated.

Reproductive risk factors for colorectal adenomatous polyps (New York City, NY, United States)

Events of reproductive life, such as parity and age at menarche, have been found in some but not all studies to be associated with risk for colorectal cancer in females. Because adenomatous polyps (adenomas) are precursors of colorectal cancer, we investigated whether reproductive variables were associated with colorectal adenomas. We conducted a case-control study among patients examined in three colonoscopy practices in New York City (NY, United States) from 1986 to 1988. Adenoma cases (n = 128) were defined as women who had an adenoma detected at the index colonoscopy with no history of inflammatory bowel disease, adenomas, or cancer. Controls (n = 283) were women with a normal index colonoscopy and no history of inflammatory bowel disease, adenomas, or cancer. The adjusted odds ratio (OR) for the association of early menarche (age less than 13 years) with adenomas was 0.6 (95 percent confidence interval = 0.4-0.9). Parity, history of spontaneous or induced abortion, infertility, type of menopause, age at menopause, use of oral contraceptives, and use of menopausal hormone replacement therapy were not associated statistically significantly with adenoma risk, although some possible trends were observed. Our findings do not implicate reproductive events, nulliparity, or overexposure to estrogens or to menstrual cycles as mechanisms of increased risk for colorectal neoplasia.

Differences in Cancer Mortality Trends between Four Neighboring North-Eastern Areas and Italy, 1970-1990

Aims and background

The present report combines descriptive statistics (partly never published) on four neighboring areas of north-eastern (NE) Italy [Friuli-Venezia Giulia (1970-89) and Veneto (1970-87) regions and the provinces of Trento (1970-89) and Bolzano (1971-90)], and all Italy (1970-89). The aim was to highlight potential differences in mortality trends and promote a more systematic sharing of data and methodologies.

Methods

Death certificates stratified by cause, sex, age and residence were obtained from official publications of the Italian Central Institute of Statistics. Absolute numbers of deaths from different causes, age-standardized rates (on the basis of the European standard population) and percentage of change over the examined period for both sexes were computed for each geographic area.

Results

Unfavorable trends were seen for neoplasms of the upper aerodigestive tract, lung, breast, colorectum, bladder, kidney and pancreas and cutaneous malignant melanoma. Increases in most of these neoplasms were more marked in the 4 NE areas than in Italy, especially with respect to cancers of the upper aerodigestive tract in both sexes and cancer of the lung and ovary in women. In Bolzano, rates of neoplasms associated with tobacco and alcohol consumption were lower and less steeply increasing than in the other NE areas, most notably Trento, therefore, contributing to produce the lowest overall cancer mortality rates of NE areas. Cancers of the stomach, uterus, and testis and Hodgkin's disease presented consistent downward trends in all examined areas.

Conclusions

The analysis of mortality trends across areas is consistent with elevated and still increasing cancer rates in the 4 NE areas considered, especially for tobacco and alcohol-related neoplasms and skin melanoma. Preventive strategies, based on epidemiologic knowledge, especially against tobacco and heavy alcohol consumption, and intense intermittent sun exposure, seem to be priorities and may benefit from systematic sharing of information, expertise and intervention tools in NE Italy. At least part of the lack of cancer deaths in Bolzano must be attributable to the deaths of Bolzano residents abroad (especially in Austria) and/or to differences in coding practices. This should be elucidated in future studies.

Biphasic actions of estrogen on colon cancer cell growth: possible mediation by high- and low-affinity estrogen binding sites

The present experiments were carried out to investigate the possible direct effects of estrogens (E) on the growth of colon cancer cells. Estradiol exhibited a concentration-dependent biphasic growth effect on a mouse colon cancer cell line (MC-26). Low concentrations of estradiol (10(-10) M: to 10(-8) M: ) had a growth-stimulatory effect, while higher concentrations (10(-7) M: to 10(-6) M: ) were growth-inhibitory. Estrogen receptor (ER) mRNA as well as specific, saturable binding of estradiol to ER (K(d)=0.3NM: , B(max)=0.72 fmol/μg DNA) was identified in these cells. In addition to the classical high affinity ER, lower affinity, higher capacity estrogen binding sites (K(d)=35MM: , B(max)=30 fmol/μg DNA) were also characterized in MC-26 cells. These two types of estrogen binding sites exhibited distinct binding specificities for E and antiestrogens. Treatment of MC-26 cells with an oligodeoxy-nucleotide antisense to the translation start codon of ER mRNA did not alter the grown-inhibitory effect of 10(-6) M: estradiol, demonstrating that the growth-inhibitory effect of high concentrations of E was not mediated by ER; we have previously shown that under the same conditions, ER antisense oligonucleotides do block the growth-stimulatory effects of 10(-9) M: E(2) in MC-26 cells. The data suggest that physiological concentrations of estradiol acting via the classical ER may have a proliferative effect on the growth of colon cancer cells. However, in situations where there are high luminal concentrations of estrogenic compounds, they may act on low affinity estrogen binding sites that mediate the growth-inhibitory effect.

The effect of different levels of dietary alpha-linolenic and other fatty acids on mammary gland ductular cell proliferation in female Swiss Webster mice

In previous work we have shown that changing the fatty acid composition of a constant amount of fat in a modified AIN-76A diet affected the level of ductular cell proliferation in the mammary glands of young virgin female Swiss Webster mice. In particular, linoleic acid concentrations of 5-10% of the total fat in the diet led to variable but appreciably higher levels of proliferation than did higher levels of linoleic acid. In this report it is shown that feeding low levels of the total fat as alpha-linolenic acid (0-5%) resulted in a similar effect. In addition the effects of other fats including menhaden oil, were further investigated.

The effects of and interactions between fermentable dietary fiber and lipid in germfree and conventional mice

BACKGROUND/AIMS

Dietary fiber can stimulate intestinal epithelial cell proliferation. The aim of this study was to resolve the different roles of fermentation and intraluminal viscosity on this trophic action and to investigate reported interactions between fiber and dietary fat.

METHODS

Conventional and germfree mice were fed guar gum in combination with low- or high-lipid diets for 2 weeks, and crypt cell production rates were determined.

RESULTS

Guar gum significantly stimulated proliferation in the small intestine, especially when combined with fat. Lipid itself also stimulated proliferation in the small intestine and had a direct trophic effect in the cecum and colon of the germfree mice. Fiber markedly stimulated proliferation in the cecum and colon but only in the conventional group. Interactions between lipid and bacteria and between guar gum and bacteria were also observed in the small intestine.

CONCLUSIONS

Guar gum has a trophic effect in the small bowel, probably related to viscosity, in addition to its fermentation-related actions in the colon. Positive interaction with lipid may be associated with delayed absorption. Lipid also has its own direct actions on small bowel mucosal proliferation, which are attenuated by the presence of bacteria.

Socioeconomic status and colon cancer incidence: a prospective cohort study

The association between socioeconomic status and colon cancer was investigated in a prospective cohort study that started in 1986 in The Netherlands among 120,852 men and women aged 55-69 years. At baseline, data on socioeconomic status, alcohol consumption and other dietary and non-dietary covariates were collected by means of a self-administered questionnaire. For data analysis a case-cohort approach was used, in which the person-years at risk were estimated using a randomly selected subcohort (1688 men and 1812 women). After 3.3 years of follow-up, 312 incident colon cancer cases were detected: 157 men and 155 women. After adjustment for age, we found a positive association between colon cancer risk and highest level of education (trend P = 0.13) and social standing (trend P = 0.008) for men. Also, male, upper white-collar workers had a higher colon cancer risk than blue-collar workers (RR = 1.42, 95% CI 0.95-2.11). Only the significant association between social standing and colon cancer risk persisted after additional adjustment for other risk factors for colon cancer (trend P = 0.005), but the higher risk was only found in the highest social standing category (RR highest/lowest social standing = 2.60, 95% CI 1.31-5.14). In women, there were no clear associations between the socioeconomic status indicators and colon cancer.