[Show abstract][Hide abstract] ABSTRACT: Studies of folate intake and colorectal cancer risk have been inconsistent. We examined the relation with colon cancer risk in a series of 13 prospective studies.
Study- and sex-specific relative risks (RRs) were estimated from the primary data using Cox proportional hazards models and then pooled using a random-effects model.
Among 725,134 participants, 5,720 incident colon cancers were diagnosed during follow-up. The pooled multivariate RRs (95% confidence interval [CI]) comparing the highest vs. lowest quintile of intake were 0.92 (95% CI 0.84-1.00, p-value, test for between-studies heterogeneity = 0.85) for dietary folate and 0.85 (95% CI 0.77-0.95, p-value, test for between-studies heterogeneity = 0.42) for total folate. Results for total folate intake were similar in analyses using absolute intake cutpoints (pooled multivariate RR = 0.87, 95% CI 0.78-0.98, comparing ≥ 560 mcg/days vs. <240 mcg/days, p-value, test for trend = 0.009). When analyzed as a continuous variable, a 2% risk reduction (95% CI 0-3%) was estimated for every 100 μg/day increase in total folate intake.
These data support the hypothesis that higher folate intake is modestly associated with reduced risk of colon cancer.
Cancer Causes and Control 11/2010; 21(11):1919-30. · 3.20 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Studies in animals have suggested that calcium may reduce the risk of colorectal cancer. However, results from epidemiologic studies of intake of calcium or dairy foods and colorectal cancer risk have been inconclusive.
We pooled the primary data from 10 cohort studies in five countries that assessed usual dietary intake by using a validated food frequency questionnaire at baseline. For most studies, follow-up was extended beyond that in the original publication. The studies included 534 536 individuals, among whom 4992 incident cases of colorectal cancer were diagnosed between 6 and 16 years of follow-up. Pooled multivariable relative risks for categories of milk intake and quintiles of calcium intake and 95% confidence intervals (CIs) were calculated. All statistical tests were two-sided.
Milk intake was related to a reduced risk of colorectal cancer. Compared with the lowest category of intake (<70 g/day), relative risks of colorectal cancer for increasing categories (70-174, 175-249, and > or =250 g/day) of milk intake were 0.94 (95% CI = 0.86 to 1.02), 0.88 (95% CI = 0.81 to 0.96), and 0.85 (95% CI = 0.78 to 0.94), respectively (P(trend)<.001). Calcium intake was also inversely related to the risk of colorectal cancer. The relative risk for the highest versus the lowest quintile of intake was 0.86 (95% CI = 0.78 to 0.95; P(trend) =.02) for dietary calcium and 0.78 (95% CI = 0.69 to 0.88; P(trend)<.001) for total calcium (combining dietary and supplemental sources). These results were consistent across studies and sex. The inverse association for milk was limited to cancers of the distal colon (P(trend)<.001) and rectum (P(trend) =.02).
Higher consumption of milk and calcium is associated with a lower risk of colorectal cancer.
[Show abstract][Hide abstract] ABSTRACT: Defining dietary patterns by factor analysis is an alternative approach to dietary assessment that has been used recently to examine diet-disease relations. However, only 1 study evaluated the reproducibility and validity of this method. Our aim was to assess both the validity and reproducibility of major dietary patterns based on data from a 60-item FFQ. We chose 2 independent random samples among over 60,000 women aged 40-74 y participating in the Swedish Mammography Cohort (SMC). In the validation study, the FFQ was compared with 4 7-d dietary records (DRs) among 129 women. For the reproducibility study, the FFQ was administered twice, 1 y apart in 212 women. By conducting factor analysis, 3 major dietary patterns were identified: healthy (high in vegetables, fruits, fish, poultry, tomato, cereal, and low-fat dairy products), Western (processed meat, meat, refined grains, sweets, and fried potatoes), and drinker (beer, wine and liquor, snacks) pattern. These 3 patterns explained 29-34% of the total variance in these 2 studies. The Spearman correlation coefficients between FFQ1 and FFQ2 (reproducibility) for healthy, Western, and drinker pattern were 0.63, 0.68, and 0.73, respectively (all P < 0.0001). Correlation coefficients between the FFQ and DRs (validity) for these patterns were 0.59, 0.50, and 0.85, respectively (all P < 0.0001). Our results indicate that identification of dietary patterns through factor analysis is a reproducible and valid method. The dietary patterns approach might be used in nutritional epidemiology as an alternative method of dietary assessment.
Journal of Nutrition 06/2004; 134(6):1541-5. · 4.20 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Obesity increases the risk of certain cancer types, e.g., cancer of the endometrium, colon and gallbladder. For some other cancer forms, e.g., prostate cancer, the association is less clear. We examined the association between body mass index (BMI) and hormone-dependent tumors, utilizing a cohort of 21,884 Swedish twins born during 1886-1925. Information about BMI at different ages and potential confounding factors was collected prospectively. The Swedish Cancer Registry was used to identify cases of cancer in the prostate (n = 666), breast (n = 607), corpus uteri (n = 150) and ovary (n = 118) during 1969-1997. The material was analyzed as a traditional cohort and with co-twin control analyses that allow for control of genetic influences. Obesity (BMI >/=30 kg/m(2)) at baseline was positively associated with cancer in the corpus uteri [relative risk (RR) = 3.03, 95% confidence interval (CI) 1.82-5.03], as was BMI at age 25, independently of BMI at baseline. Increased risk was also found for breast cancer but only in older women (>/=70 years). Overweight at age 25 was associated with decreased risk of breast cancer (RR = 0.51, 95% CI 0.33-0.78). No association was found for prostate cancer. We conclude that age is an important effect modifier of cancer risk associated with obesity and that obesity and overweight in young adult life may affect cancer risk also later in life.
International Journal of Cancer 10/2003; 106(4):594-9. · 6.20 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Many studies of fruit and vegetable consumption showed inverse associations with breast cancer risk, suggesting the potential importance of carotenoids (and other phytochemicals) contained in these foods. To date, however, only one prospective cohort study has examined dietary carotenoids other than beta-carotene in relation to breast cancer risk.
Our aim was to examine the relations between dietary intakes of beta-carotene, alpha-carotene, beta-cryptoxanthin, lycopene, and lutein + zeaxanthin and breast cancer risk in a large cohort study of Canadian women.
A case-cohort analysis was undertaken in a cohort of 56 837 women who were enrolled in the Canadian National Breast Screening Study and who completed a self-administered dietary questionnaire. During follow-up to the end of 1993 a total of 1589 women were diagnosed with biopsy-confirmed incident breast cancer. For comparison, a subcohort of 5681 women was randomly selected. After exclusions for various reasons, the analyses were based on 1452 cases and 5239 noncases.
We found no clear association between intakes of any of the studied carotenoids and breast cancer risk in the study population as a whole or in subgroups defined by smoking status; relative body weight (assessed by body mass index); intakes of total fat, energy, alcohol, or folic acid; family history of breast cancer; or menopausal status.
Our data do not support any association between dietary intakes of the studied carotenoids and breast cancer risk. However, prospective cohort studies of carotenoids in relation to breast cancer are scarce and further studies are warranted.
American Journal of Clinical Nutrition 11/2002; 76(4):883-8. · 6.50 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: The epidemiologic association between physical activity and breast cancer has been corroborated in many studies. Some inconsistencies remain, possibly due to variation in life periods for exposure assessment, confounding and undetected effect modification. In our cohort study, we address some of these questions by taking into account physical activity in different periods of life and by investigating effect modification by birth cohort and body mass index (BMI). Altogether 9,539 same-sex twin women aged 42-70 years who answered a questionnaire about their work and leisure-time physical exercise from ages 25 to 50 during 1967 and 1970 were included in our cohort. During follow-up, 506 breast cancer cases occurred through 1997. We used multivariate Cox models to estimate relative risk (RR) with 95% confidence interval (CI). We found no associations between physical activity and breast cancer overall. Women born between 1901 and 1917 (aged 51-70 at baseline) who reported regular leisure-time activity had a borderline significant 40% lower risk compared with those who reported no activity (RR 0.6; 95% CI 0.4-1.0; test for trend, p = 0.07). This association appeared to be confined to women with a low BMI after the age of 50 and to women with a high BMI during the premenopausal period. We found no evidence that work activity reduces risk for breast cancer. The importance of physical activity for breast cancer risk seems to depend on birth cohort. The association may be limited to normal-weight postmenopausal women and overweight premenopausal women.
International Journal of Cancer 08/2002; 100(1):76-81. · 6.20 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Folate is crucial for normal DNA methylation, synthesis and repair, and deficiency of this nutrient is hypothesized to lead to cancer through disruption of these processes. There is some evidence to suggest that relatively high dietary folate intake might be associated with reduced colorectal cancer risk, especially among individuals with low methionine intake. A case-cohort analysis was undertaken within the cohort of 56,837 women who were enrolled in the Canadian National Breast Screening Study and who completed a self-administered dietary questionnaire. During follow-up to the end of 1993, a total of 389 women were diagnosed with colorectal cancer, identified by linkage to the Canadian Cancer Database. For comparative purposes, a subcohort of 5,681 women was randomly selected from the full dietary cohort at baseline. After exclusions for various reasons, the analyses were based on 295 cases and 5,334 non-cases. Folate intake was inversely associated with colorectal cancer risk (IRR = 0.6, 95% CI = 0.4-1.1, p for trend = 0.25). The inverse association was essentially similar among individuals with low and high methionine intake, and was similar for colon and rectal cancers when those endpoints were analyzed separately. Among individuals with low methionine intake, folate intake did not appear to lower the risk of rectal cancer, a finding that may be due, in part, to the low number of cases in the subgroup analysis. Overall, our data lend some support to the hypothesis that high folate intake is associated with a reduced risk of colorectal cancer.
International Journal of Cancer 03/2002; 97(6):864-7. · 6.20 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: The incidence of endometrial cancer varies up to 10-fold between high- and low-incidence regions, suggesting the importance of environmental factors, including diet, in the etiology of this disease. However, few studies have examined the role of diet in the etiology of endometrial cancer. Using unconditional logistic regression to estimate odds ratios (OR) and 95% confidence intervals (CI), we analyzed data from a large, case-control study of Swedish-born postmenopausal women aged 50-74 yr (709 cases and 2,887 controls) residing in Sweden between 1994 and 1995. We found no clear association between foods or food groups and endometrial cancer risk, although high consumption of certain foods, such as Brassica vegetables, coffee, and legumes, might be associated with small-to-moderate reduced risks of endometrial cancer, while red meat consumption might be associated with a small-to-moderate increased risk. Daily use of calcium supplements appeared to lower endometrial cancer risk (OR = 0.5, 95% CI = 0.3-0.9, P for trend = 0.04), especially among women with low calcium intake from dairy products. On the other hand, the use of iron supplements appeared to increase the risk (OR = 1.7, 95% CI = 0.9-3.3, P for trend = 0.03). The findings are discussed with respect to previous studies and the possible underlying mechanisms.
Nutrition and Cancer 02/2002; 42(1):25-32. · 2.70 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Although laboratory data and a few adenoma prevention trials suggest that calcium supplementation may reduce the risk of colorectal neoplasia, the results of observational studies of calcium intake and colorectal cancer risk are contradictory. However, few studies have examined the association among women or effects in specific colon subsites. Women with colorectal cancer diagnosed through 31 December 2000 were identified by linkage to regional cancer registries. During an average 11.3 yr of follow-up of 61,463 women, we observed 572 incident cases of colorectal cancer. Using data obtained from a 67-item food frequency questionnaire and Cox proportional hazards models to estimate rate ratios and 95% confidence intervals, we found an inverse association between dietary calcium intake and colorectal cancer risk. Women with the highest calcium intake (median 914 mg/day) had a reduced risk of colorectal cancer (rate ratio = 0.72, 95% confidence interval = 0.056-0.93, P for trend = 0.02) compared with women with the lowest intake (median 486 mg/day). Furthermore, our results suggest that the inverse association may be strongest in relation to distal cancers and among older women. The association with dairy products was less clear, suggesting that calcium intake per se is more important than specific calcium sources. Vitamin D intake was not clearly associated with risk. In sum, our data suggest that high calcium intake may lower colorectal cancer risk.
Nutrition and Cancer 02/2002; 43(1):39-46. · 2.70 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Several studies have found inverse associations between fruit and vegetable consumption and colorectal cancer risk, suggesting the potential etiological importance of carotenoids (and other phytochemicals) contained in these foods. However, only one study (a case-control study) has examined the association between dietary carotenoids other than beta-carotene and colorectal cancer risk. In the study reported here, we examined the relationships between dietary intakes of beta-carotene, alpha-carotene, lycopene, lutein, and beta-cryptoxanthin and colorectal cancer risk in a large cohort study of Canadian women. A case-cohort analysis was undertaken within the cohort of 56,837 women who were enrolled in the Canadian National Breast Screening Study and who completed a self-administered dietary questionnaire. During follow-up to the end of 1993, a total of 388 women were diagnosed with colorectal cancer. For comparative purposes, a subcohort of 5,681 women was randomly selected. After exclusions for various reasons, the analyses were based on 295 cases and 5,334 noncases. We did not find any clear association between intake of any of the studied carotenoids and colorectal cancer risk in the study population as a whole or in subgroups defined by smoking status, relative body weight (body mass index), intakes of total fat, energy, alcohol, and folic acid, or menopausal status. Our data do not support any association between dietary intakes of the studied carotenoids and colorectal cancer risk. However, given that this is the first prospective cohort study of carotenoids in relation to colorectal cancer, further studies are warranted.
Nutrition and Cancer 02/2002; 42(2):167-72. · 2.70 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: The consumption of fatty fish, which contains large amounts of omega-3 fatty acids, may lower the risk of hormone-responsive cancers. Our aim was to study the association of fish consumption and endometrial cancer risk in Sweden, a country with a wide range of high fatty fish consumption. Using data from a large, nationwide case-control study (709 cases and 2888 controls), we analyzed consumption of both fatty (e.g., salmon and herring) and lean (e.g., cod and flounder) fish in relation to endometrial cancer risk, adjusting estimates for a wide range of potentially confounding variables. Odds ratios (ORs) and 95% confidence intervals (CIs) were computed from unconditional logistic regression models fit by maximum likelihood methods. Consumption of fatty fish was inversely associated with endometrial cancer risk. The multivariate OR for women in the highest quartile level (median, 2.0 servings per week), compared to women with in the lowest (median, 0.2 servings per week), was 0.6 (95% CI, 0.5-0.8; P for trend, 0.0002). The corresponding OR for women in the highest quartile level of lean fish (median, 2.5 servings per week), compared to women in the lowest (median, 0.6 servings per week), was 1.0 (95% CI, 0.8-1.3; P-value for trend, 0.72). Total fish consumption was inversely associated with risk, although weakly. Our results suggest that the consumption of fatty fish, but not other types of fish, may decrease the risk of endometrial cancer.
[Show abstract][Hide abstract] ABSTRACT: A number of prospective cohort studies have examined the relations of individual dietary variables to risk of colorectal cancer. Few studies have addressed the broader eating patterns that reflect many dietary exposures working together. Using data from a prospective study of 61,463 women, with an average follow-up period of 9.6 years (between 1987 and 1998) and 460 incident cases of colorectal cancer, the authors conducted a factor analysis to identify and examine major dietary patterns in relation to colorectal cancer risk. Using proportional hazards regression to estimate relative risks, the authors found no clear association between a “Western,” “healthy,” or “drinker” dietary pattern and colorectal cancer risk. However, the data suggested that consuming low amounts of foods that constitute a “healthy” dietary pattern may be associated with increased risks of colon and rectal cancers. An inverse association with the “healthy” dietary pattern was found among women under age 50 years, although the number of cancers in this age group was limited and interpretation of this finding should be cautious. In this age group, relative risks for women in increasing quintiles of the “healthy” dietary pattern, compared with the lowest quintile, were 0.74 (95% confidence interval (CI): 0.41, 1.31), 0.69 (95% CI: 0.39, 1.24), 0.59 (95% CI: 0.32, 1.07), and 0.45 (95% CI: 0.23, 0.88) ( p for trend = 0.03). The role of overall eating patterns in predicting colorectal cancer risk requires further investigation.
American Journal of Epidemiology 01/2002; · 4.78 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Our aim was to study the broader eating patterns that potentially reflect many dietary exposures working together in their association with breast cancer risk. Using data from a prospective study of 61,463 women with an average follow-up of 9.6 years and 1,328 incident cases of breast cancer, we conducted a factor analysis to identify major dietary patterns. Proportional hazards regression was used to estimate hazard ratios. We found no association between the "Western" dietary pattern (characterized by such foods as red and processed meats, refined grains, fat, and sweets) or the "healthy" dietary pattern (fruit and vegetables, fish and poultry, low-fat dairy, and whole grains) and breast cancer risk. However, women who were in the highest category of the "drinker" dietary pattern (wine, beer, and spirits) had a moderately increased risk (rate ratio = 1.27; 95% confidence interval, 1.06-1.52; P for trend, 0.002). The positive association was somewhat weaker among women below 50 years of age, a finding not inconsistent with chance. Our results are in agreement with the majority of previous studies that show alcohol consumption moderately increases the risk of breast cancer, but our results do not support any association between breast cancer risk and the "Western" or "healthy" dietary patterns.
[Show abstract][Hide abstract] ABSTRACT: The omega-3 fatty acids, especially long-chain eicosapentaenoic acid (20:5n-3) and docosahexaenoic (22:6n-3) contained in "fatty" fish, have consistently been shown to retard the growth of breast cancer in vitro and in animal experiments. In contrast, studies of the association between fish consumption and breast cancer risk in human populations have not consistently shown inverse associations. However, previous studies have not considered the specific types of fish consumed. Using data from a large, nationwide case-control study conducted in Sweden, we examined the association between consumption of fatty and lean fish and breast cancer risk. Odds ratios (OR) and 95% confidence intervals were computed from unconditional logistic regression models. High consumption of fish was weakly associated with reduced breast cancer risk, and the association was not statistically significant. With multivariate adjustment, the OR for women with the highest consumption (> or =3.5 servings/wk) compared with women with the lowest (virtually none) was 0.88 (95% confidence interval = 0.60-1.29, P for trend = 0.15). When type of fish was examined separately, the association was similar for fatty and lean fish.
Nutrition and Cancer 01/2002; 44(1):1-6. · 2.70 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Fruit and vegetables are considered to be important means of preventing cancer through diet. However, several recent large prospective cohort studies and clinical trials have found no associations regarding several major cancers, including cancers of the colon, breast and stomach. Although these results are disconcerting, especially for health-conscious individuals, there is also mounting evidence that people who avoid fruit and vegetables completely, or consume very little, are indeed at increased risk of these cancers. These individuals in particular should be identified, with the goal of helping them find ways to include more fruit and vegetables in their diets.
Journal of Internal Medicine 11/2001; 250(4):280-90. · 6.46 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: The incidence of adenocarcinoma of the oesophagus has increased rapidly in recent decades. In order to appreciate the potential for prevention by means of dietary modification, we estimated the aetiological fractions and the increments in absolute risk attributable to low intake of fruit and vegetables for adenocarcinoma and squamous cell carcinoma of the oesophagus and for adenocarcinoma of the gastroesophageal junction. We conducted a nationwide population-based case-control study in Sweden, with participation of 608 cases and 815 controls. We used unconditional logistic regression to estimate relative risks, from which we calculated aetiological fractions. Individuals in the highest exposure quartile (median 4.8 servings/day) versus the lowest (median 1.5 servings/day) showed approximately 50% lower risk of oesophageal adenocarcinoma and 40% lower risk of oesophageal squamous cell carcinoma, but no risk reduction for gastric cardia adenocarcinoma. Approximately 20% of oesophageal adenocarcinoma, and likewise squamous cell carcinoma, in Sweden was attributed to consuming less than three servings of fruit and vegetables per day. A very large number of individuals (over 25,000) would need to increase their fruit and vegetable consumption moderately in order to prevent one oesophageal cancer per year. Moderate relative risk reductions translate into weak absolute risk reductions for oesophageal cancers in Sweden.
European Journal of Cancer Prevention 09/2001; 10(4):365-9. · 2.97 Impact Factor