Ethnic differences in mammographic densities

Trends and dietary determinants of overweight and obesity in a multiethnic population

OBJECTIVES

To describe trends in BMI among different ethnic groups in Hawaii and to explore the relation of nutrient and food intake with excess weight.

RESEARCH METHODS AND PROCEDURES

We pooled demographic, anthropometric, and nutritional data derived from a detailed diet history for 159,683 participants of 18 population-based epidemiological studies conducted in Hawaii over a 25-year period. The age-adjusted prevalence of excess weight (BMI > or = 25 kg/m(2)) was estimated for 5-year intervals. To explore dietary determinants of excess weight, we computed odds ratios using logistic regression.

RESULTS

During the study period, the prevalence of excess weight increased considerably among all ethnic groups. Native Hawaiians had the highest and Asian Americans had the lowest prevalence of excess weight at all times. Although the percentage of calories consumed from carbohydrates increased, the percentage of calories from fat decreased over time. On an individual level, fat and protein consumption predicted a higher BMI, and dietary fiber intake predicted a lower BMI. Similarly, a higher consumption of meat, poultry, and fish was related to excess weight, whereas fruit and vegetable intake were inversely associated with excess weight. After stratification by ethnicity, the associations were not materially altered among women, but carbohydrates seemed to have a stronger association with excess weight among Native Hawaiian and Japanese men than among white men.

DISCUSSION

In this large ethnically diverse population, plant-based foods and dietary fiber emerged as a potential protective factor against excess weight regardless of ethnicity.

Mammographic density and breast cancer risk: the multiethnic cohort study

In a nested case-control study (2001-2004), the authors investigated the association between mammographic density and breast cancer risk among women of Caucasian, Japanese, and Native Hawaiian ancestry in the Hawaii component of the Multiethnic Cohort Study. The authors retrieved several prediagnostic mammograms for breast cancer cases and for controls frequency-matched to cases by age and ethnicity. A reader who was blinded to case status and year of mammogram performed computer-assisted density assessment. Suitable mammographic readings were obtained for 607 cases and 667 controls. The authors used unconditional logistic regression to estimate odds ratios and 95% confidence intervals while adjusting for confounders. Mean percent density and mean dense area were significantly greater for cases than for controls: 39.6% vs. 29.7% and 37.3 cm2 vs. 28.4 cm2, respectively. For the earliest mammogram taken, the overall odds ratio for a 10% increase in breast density was 1.22 (95% confidence interval: 1.14, 1.30), and the overall odds ratio for a 10-cm2 increase in dense area was 1.17 (95% confidence interval: 1.11, 1.24). The similar sizes of the areas under the receiver operating characteristic curve (0.66) confirmed that percent density and dense area predicted breast cancer equally well. Because the risk estimates appeared higher for Caucasians and Native Hawaiians than for Japanese women, ethnicity-specific models may be necessary to predict risk from breast density in different ethnic groups.

Percentage density, Wolfe's and Tabár's mammographic patterns: agreement and association with risk factors for breast cancer

Introduction

The purpose of this report was to classify mammograms according to four methods and to examine their agreement and their relationship to selected risk factors for breast cancer.

Method

Mammograms and epidemiological data were collected from 987 women, aged 55 to 71 years, attending the Norwegian Breast Cancer Screening Program. Two readers each classified the mammograms according to a quantitative method (Cumulus or Madena software) and one reader according to two qualitative methods (Wolfe and Tabár patterns). Mammograms classified in the reader-specific upper quartile of percentage density, Wolfe's P2 and DY patterns, or Tabár's IV and V patterns, were categorized as high-risk density patterns and the remaining mammograms as low-risk density patterns. We calculated intra-reader and inter-reader agreement and estimated prevalence odds ratios of having high-risk mammographic density patterns according to selected risk factors for breast cancer.

Results

The Pearson correlation coefficient was 0.86 for the two quantitative density measurements. There was moderate agreement between the Wolfe and Tabár classifications (Kappa = 0.51; 95% confidence interval 0.46 to 0.56). Age at screening, number of children and body mass index (BMI) showed a statistically significant inverse relationship with high-risk density patterns for all four methods (all P < 0.05). After adjustment for percentage density, the Wolfe classification was not associated with any of the risk factors for breast cancer, whereas the association with number of children and BMI remained statistically significant for the Tabár classification. Adjustment for Wolfe or Tabár patterns did not alter the associations between these risk factors and percentage mammographic density.

Conclusion

The four assessments methods seem to capture the same overall associations with risk factors for breast cancer. Our results indicate that the quantitative methods convey additional information over the qualitative methods.

A 2-year soy intervention in premenopausal women does not change mammographic densities

Soy consumption may be related to lower breast cancer risk as assessed by breast density. The aims of this 2-y trial were to examine the effects of soy foods and lifetime soy intake on mammographic density. After 220 premenopausal women were randomly assigned to the intervention or control group, the former group consumed 2 daily servings of soy foods equivalent to 50 mg of isoflavones and the latter consumed their regular diet. The respective dropout rates were 15.6 and 12.6%; adherence to the study regimen was high. We assessed lifetime soy intake with a questionnaire and measured breast density in screening mammograms obtained at baseline and at the end of the trial for 98 intervention and 103 control women using a computer-assisted method. None of the mammographic outcomes differed significantly by experimental group. The total area of the breast increased and the size of the dense areas decreased significantly over time in both groups. After 2 y, the mean percentage density had decreased by 2.8 and 4.1% in intervention and control women, respectively. Women who reported eating more soy during their lives had higher percentage densities than women whose diet included little soy; this difference was significant only in Caucasians. Lower soy intake during early life and higher soy intake during adulthood predicted a greater reduction in the percentage density during the study period. After 2 y of intervention, we observed no significant differences in mammographic densities by intervention status, but it appears that soy consumption throughout life may have some effect on breast density.

Risk Factors for Breast Cancer Associated with Mammographic Features in Singaporean Chinese Women

Background: Mammographic density has been found to be a strong risk factor for breast cancer and to be associated with age, body weight, parity, and menopausal status. Most studies to date have been carried out in Western populations. The purpose of the study described here was to determine in a cross-sectional study in a Singaporean Chinese population the demographic, menstrual, reproductive, and anthropometric factors that are associated with quantitative variations in age-adjusted percentage mammographic densities and to examine the association of these factors with the dense and nondense areas of the mammogram.

Method: We used mammograms and questionnaire data collected from subjects in the Singapore Breast Screening Project. Women ages 45 to 69 years participated and 84% of those screened were Chinese. Mammograms were digitized and percentage density was measured and analyzed in relation to the questionnaire data.

Results: Percentage mammographic density was associated with several risk factors for breast cancer, most of them also associated, in opposite directions, with the dense and nondense components of the image. Percentage density was associated with age and weight (both negatively), height and age at first birth (both positively), and number of births and postmenopausal status (both negatively). Percentage density was weakly associated with a previous breast biopsy but was not associated with age at menarche or menopause, with use of hormones, or with a family history of breast cancer.

Conclusion: Percentage mammographic density in Singaporean Chinese women has similar associations with risk factors for breast cancer to those seen in Caucasians.

A comparison of dietary habits among women in Japan and Hawaii

OBJECTIVE

To compare the dietary habits of Japanese women in Japan with those of Japanese and Caucasian women living in Hawaii.

DESIGN

Data from two previous cross-sectional studies conducted within two years in Hawaii and Gifu, Japan were pooled and analysed. Dietary intakes were assessed with validated food-frequency questionnaires and urine samples were collected for isoflavone measurement.

SETTING

Participants were recruited through mammography clinics in both locations.

SUBJECTS

In Hawaii, 164 Caucasian and 146 Japanese women; in Japan, 206 women.

RESULTS

Dietary habits differed considerably by ethnicity and location. In comparison to the Caucasian diet, the diet in Japan was relatively low in fat and high in carbohydrates and protein, whereas the Japanese women in Hawaii reported intermediate intakes. Japanese women in Gifu consumed a diet that was relatively high in fish, soy, eggs and vegetables, and low in fruits, dairy products and meat. In contrast, the Caucasian women consumed the most dairy products and fruits and the Japanese women in Hawaii reported the highest grain and meat intakes.

CONCLUSIONS

The diet of Japanese women in Hawaii appeared to be a combination of foods eaten in Japan and the dietary habits of Caucasian women in Hawaii, but eating habits in Japan are also different from traditional nutritional patterns. This study illustrates several problems related to dietary comparisons across populations and provides information for future investigations on chronic disease risk.

Analysis of sonographic features for the differentiation of benign and malignant breast tumors of different sizes

OBJECTIVE

To analyze the value of various sonographic features in differentiating benign from malignant breast tumors of different sizes to improve the diagnostic accuracy in small lesions.

METHODS

The sonographic features of 1203 histologically confirmed solid breast lesions were prospectively documented with respect to anteroposterior (AP) diameter/width ratio, shape, margin, echogenicity, echotexture, posterior echo and bilateral refraction sign. The sensitivity, specificity and accuracy of breast ultrasound were calculated for lesions grouped according to size (< or = 1, 1.1-2 and > 2 cm). Univariate and multiple logistic regression analyses including calculation of odds ratios for single sonographic features were used to analyze the significance of the different diagnostic features.

RESULTS

The accuracy of breast sonography in differentiating between benign and malignant tumors < or = 1, 1.1-2 and > 2 cm in size was 75.6%, 86.4% and 88.4%, respectively. Univariate analysis demonstrated that all sonographic features were significant in tumors > or = 1.1 cm. Shape, margin, echogenicity and echotexture were the significant factors in those tumors < or = 1 cm. Multiple logistic regression analysis demonstrated that margin, shape, posterior echo and echogenicity were the significant factors for differential diagnosis in tumors > 2 cm. Echogenicity, margin, shape, bilateral refraction sign and echotexture were the significant factors for tumors 1.1-2 cm. On multiple regression analysis, margin was the only significant factor for tumors < or = 1 cm.

CONCLUSION

Tumor margin is the most important sonographic feature in evaluating breast lesions in any size group. With the combination of significant factors and emphasis on specific features according to size of lesion, the diagnostic accuracy of ultrasound for the differential diagnosis of malignant and benign tumors may be improved.

Comparison of mammographic densities and their determinants in women from Japan and Hawaii

Breast cancer incidence increases considerably in women who migrate from Japan to the United States. Based on the hypothesis that mammographic density in healthy mammograms reflects differences in breast cancer risk, we compared mammographic density in 3 groups of women at different levels of risk: Caucasian and Japanese women in Hawaii and Japanese women in Japan. In a cross-sectional design, pre- and postmenopausal women without a history of breast cancer and with a mammogram free of suspicious lesions were recruited in mammography clinics and completed a self-administered questionnaire. Cranio-caudal mammograms were scanned into a computer and the densities measured using a computer-assisted method. Statistical analyses included ANOVA and multiple linear regression. Breast size among women of Japanese ancestry was similar in Hawaii and Japan but 50% smaller than that among Caucasian women. Dense areas were smallest among women in Japan, intermediate among Japanese women in Hawaii and largest among Caucasian women. Percent densities were greater in Japanese women than Caucasian women because of the larger breast sizes in Caucasians. However, percent densities were significantly higher among Japanese women in Hawaii than in Japan. These results indicate that the size of the total breast differs primarily by ethnicity and the size of the dense areas differs mainly by place of residence. Therefore, when comparing ethnic groups with distinct physical proportions, the absolute size of the dense areas appears to be a better measure of breast cancer risk than the relative density.