Showing papers by "Alicja Wolk published in 2000"

Pooled Analysis of Prospective Cohort Studies on Height, Weight, and Breast Cancer Risk

Abstract: The association between anthropometric indices and the risk of breast cancer was analyzed using pooled data from seven prospective cohort studies. Together, these cohorts comprise 337,819 women and 4,385 incident invasive breast cancer cases. In multivariate analyses controlling for reproductive, dietary, and other risk factors, the pooled relative risk (RR) of breast cancer per height increment of 5 cm was 1.02 (95% confidence interval (Cl): 0.96, 1.10) in premenopausal women and 1.07 (95% Cl: 1.03, 1.12) in postmenopausal women. Body mass index (BMI) showed significant inverse and positive associations with breast cancer among pre- and postmenopausal women, respectively; these associations were nonlinear. Compared with premenopausal women with a BMI of less than 21 kg/m2, women with a BMI exceeding 31 kg/m2 had an RR of 0.54 (95% Cl: 0.34, 0.85). In postmenopausal women, the RRs did not increase further when BMI exceeded 28 kg/m2; the RR for these women was 1.26 (95% Cl: 1.09, 1.46). The authors found little evidence for interaction with other breast cancer risk factors. Their data indicate that height is an independent risk factor for postmenopausal breast cancer; in premenopausal women, this relation is less clear. The association between BMI and breast cancer varies by menopausal status. Weight control may reduce the risk among postmenopausal women.

Social mapping of the obesity epidemic in Sweden

Abstract: OBJECTIVE: The aim of the present study is to describe the evolution of the obesity epidemic in Sweden, with specific attention to the socioeconomic gradient. DESIGN: Data from the Swedish Surveys of Living Conditions were used. Three such surveys were undertaken in 1980/81, 1988/89, and 1996/97, each of which was based on a simple random sample from the national population registry. SUBJECTS: A total of 38,284 observations are used in this analysis, including males and females aged 16–84. The sample is approximately equally divided among the 3 survey periods and by gender. MEASUREMENTS: The following body weight categories are used to describe changing prevalences: overweight (BMI≥25), obesity (BMI≥30) and underweight (BMI<18.5). Because body weight and heights were self-reported, recorded values were adjusted for estimating gender-specific obesity prevalences. Education was used as a proxy for socioeconomic status. RESULTS AND CONCLUSIONS: The prevalence of BMI≥30 increased significantly over the 16-year observation period. At the time of the 1980/81 survey, the adjusted estimates were 8.8% in women and 6.6% in men, compared to 11.9% and 10.0% respectively, in 1996/97. The prevalence of BMI≥25 was also analyzed for time trends, with specific attention to populations at risk. The largest proportionate changes occurred in women aged 16–44, among whom the prevalence of overweight doubled. The inverse educational gradient with respect to obesity is still present in both sexes, but there is no indication that it has increased in magnitude between 1980/81–1996/97.

Antioxidants and cancers of the esophagus and gastric cardia.

Abstract: Antioxidant vitamins have attracted considerable attention in previous studies of esophageal squamous-cell carcinoma, but dietary studies of adenocarcinoma of the esophagus and gastric cardia remain sparse. Treating these tumors as distinct diseases, we studied intakes of vitamin C, beta-carotene and alpha-tocopherol in a nationwide population-based case-control study in Sweden, with 185, 165, and 258 cases of esophageal adenocarcinoma, esophageal squamous-cell carcinoma, and gastric cardia adenocarcinoma, respectively, and 815 controls. Subjects with a high parallel intake of vitamin C, beta-carotene, and alpha-tocopherol showed a 40-50% decreased risk of both histological types of esophageal cancer compared with subjects with a low parallel intake. Antioxidant intake was not associated with the risk of gastric cardia adenocarcinoma. Separately, vitamin C and beta-carotene reduced the risk of esophageal cancers more than alpha-tocopherol. We found that antioxidant intake is associated with similar risk reductions for both main histological types of esophageal cancer. Our findings indicate that antioxidants do not explain the diverging incidence rates of the 2 histological types of esophageal cancer. Moreover, our data suggest that inverse associations with esophageal squamous-cell carcinoma and adenocarcinoma may be stronger among subjects under presumed higher oxidative stress due to smoking or gastroesophageal reflux, respectively. Our results may be relevant for the implementation of focused, cost-effective preventive measures.

Dietary antioxidant intake and the risk of cardia cancer and noncardia cancer of the intestinal and diffuse types: a population-based case-control study in Sweden

Abstract: In spite of diverging incidence trends, subsite, and subtype-specific gastric cancer data on the association with dietary antioxidants are sparse. We aimed to test whether the apparent protective effect of antioxidants is mainly confined to noncardia (distal) cancer of the intestinal subtype, to which most of the incidence decline in gastric cancer has been ascribed. In a Swedish study base (total population 1.3 million), we interviewed 567 cases uniformly classified to subsite (cardia vs. noncardia) and subtype (intestinal vs. diffuse), and 1165 population-based controls, frequency matched for age and sex. Serologic data on H. pylori status was available for a subset of 542 individuals. Ascorbic acid (vitamin C) was inversely associated with all subsites and subtypes of gastric cancer in a significant dose-response manner (all p<0.05), with risk reductions between 40% and 60%. beta-carotene was also strongly and negatively associated with risk, particularly with the intestinal type. The associations with alpha-tocopherol (vitamin E) were less clear. The highest parallel intake of all three antioxidants (quartiles 4), compared to those with the lowest parallel intakes (quartiles 1), was associated with a 70% lower risk of developing noncardia cancer (OR 0.3, 95% CI 0.1-0.9). Our results suggest that antioxidants might be especially beneficial among subjects at increased risk for gastric cancer such as smokers and those infected by H. pylori. We conclude that a high intake of antioxidants, as a consequence of high consumption of fruit and vegetables, may lower the risk not only for gastric cancer of the intestinal type, but also for diffuse type adenocarcinoma and cardia cancer.

Reflux-inducing dietary factors and risk of adenocarcinoma of the esophagus and gastric cardia.

Abstract: Gastroesophageal reflux (GER) is the strongest known risk factor for esophageal adenocarcinoma. For long-term sufferers with severe symptoms, the excess risk may exceed 40-fold. GER has also been shown to increase the risk of cancers of the gastric cardia more than fourfold. Several foods, including dietary fat, chocolate, mints, coffee, onions, citrus fruit, and tomatoes, have been associated with temporary symptoms of reflux, most likely through a relaxation of the lower esophageal sphincter (LES). Our aim was to determine whether these foods are associated with risk of adenocarcinoma of the esophagus or gastric cardia. We studied intakes of LES-relaxing foods and other dietary habits potentially associated with reflux in a nationwide population-based case-control study in Sweden, with 185 and 258 cases of esophageal adenocarcinoma and gastric cardia adenocarcinoma, respectively, and 815 controls. We found no association between LES-relaxing foods and symptoms of chronic reflux, although this might be due to avoidance of these foods among sufferers. In addition, we found no association between dietary factors known to cause LES relaxation and the risk of adenocarcinoma of the esophagus or gastric cardia. Our findings indicate that dietary factors associated with LES relaxation and transient GER (but perhaps not severe chronic reflux) are not associated with any important risk of esophageal malignancy.