Showing papers by "Cynthia A. Thomson published in 2006"

Low-Fat Dietary Pattern and Risk of Invasive Breast Cancer: The Women's Health Initiative Randomized Controlled Dietary Modification Trial

Abstract: ContextThe hypothesis that a low-fat dietary pattern can reduce breast cancer risk has existed for decades but has never been tested in a controlled intervention trial.ObjectiveTo assess the effects of undertaking a low-fat dietary pattern on breast cancer incidence.Design and SettingA randomized, controlled, primary prevention trial conducted at 40 US clinical centers from 1993 to 2005.ParticipantsA total of 48 835 postmenopausal women, aged 50 to 79 years, without prior breast cancer, including 18.6% of minority race/ethnicity, were enrolled.InterventionsWomen were randomly assigned to the dietary modification intervention group (40% [n = 19 541]) or the comparison group (60% [n = 29 294]). The intervention was designed to promote dietary change with the goals of reducing intake of total fat to 20% of energy and increasing consumption of vegetables and fruit to at least 5 servings daily and grains to at least 6 servings daily. Comparison group participants were not asked to make dietary changes.Main Outcome MeasureInvasive breast cancer incidence.ResultsDietary fat intake was significantly lower in the dietary modification intervention group compared with the comparison group. The difference between groups in change from baseline for percentage of energy from fat varied from 10.7% at year 1 to 8.1% at year 6. Vegetable and fruit consumption was higher in the intervention group by at least 1 serving per day and a smaller, more transient difference was found for grain consumption. The number of women who developed invasive breast cancer (annualized incidence rate) over the 8.1-year average follow-up period was 655 (0.42%) in the intervention group and 1072 (0.45%) in the comparison group (hazard ratio, 0.91; 95% confidence interval, 0.83-1.01 for the comparison between the 2 groups). Secondary analyses suggest a lower hazard ratio among adherent women, provide greater evidence of risk reduction among women having a high-fat diet at baseline, and suggest a dietary effect that varies by hormone receptor characteristics of the tumor.ConclusionsAmong postmenopausal women, a low-fat dietary pattern did not result in a statistically significant reduction in invasive breast cancer risk over an 8.1-year average follow-up period. However, the nonsignificant trends observed suggesting reduced risk associated with a low-fat dietary pattern indicate that longer, planned, nonintervention follow-up may yield a more definitive comparison.Clinical Trials RegistrationClinicalTrials.gov Identifier: NCT00000611

Dietary Fat Reduction and Breast Cancer Outcome: Interim Efficacy Results From the Women's Intervention Nutrition Study

Abstract: Background: Preclinical and observational studies suggest a relationship between dietary fat intake and breast cancer, but the association remains controversial. We carried out a randomized, prospective, multicenter clinical trial to test the effect of a dietary intervention designed to reduce fat intake in women with resected, early-stage breast cancer receiving conventional cancer management. Methods: A total of 2437 women were randomly assigned between February 1994 and January 2001 in a ratio of 40 : 60 to dietary intervention (n = 975) or control (n = 1462) groups. An interim analysis was performed after a median follow-up of 60 months when funding for the intervention ceased. Mean differences between dietary intervention and control groups in nutrient intakes and anthropometric variables were compared with t tests. Relapse-free survival was examined using Kaplan-Meier analysis, stratified log-rank tests, and Cox proportional hazards models. Statistical tests were two-sided. Results: Dietary fat intake was lower in the intervention than in the control group (fat grams/day at 12 months, 33.3 [95% confidence interval {CI} = 32.2 to 34.5] versus 51.3 [95% CI = 50.0 to 52.7], respectively; P<.001), corresponding to a statistically significant (P =.005), 6-pound lower mean body weight in the intervention group. A total of 277 relapse events (local, regional, distant, or ipsilateral breast cancer recurrence or new contralateral breast cancer) have been reported in 96 of 975 (9.8%) women in the dietary group and 181 of 1462 (12.4%) women in the control group. The hazard ratio of relapse events in the intervention group compared with the control group was 0.76 (95% CI = 0.60 to 0.98, P =.077 for stratified log rank and P =.034 for adjusted Cox model analysis). Exploratory analyses suggested a differential effect of the dietary intervention based on hormonal receptor status. Conclusions: A lifestyle intervention reducing dietary fat intake, with modest influence on body weight, may improve relapse-free survival of breast cancer patients receiving conventional cancer management. Longer, ongoing nonintervention follow-up will address original protocol design plans, which called for 3 years of follow-up after completion of recruitment.

Low-fat dietary pattern and weight change over 7 years: the Women's Health Initiative Dietary Modification Trial.

Abstract: ContextObesity in the United States has increased dramatically during the past several decades. There is debate about optimum calorie balance for prevention of weight gain, and proponents of some low-carbohydrate diet regimens have suggested that the increasing obesity may be attributed, in part, to low-fat, high-carbohydrate diets.ObjectivesTo report data on body weight in a long-term, low-fat diet trial for which the primary end points were breast and colorectal cancer and to examine the relationships between weight changes and changes in dietary components.Design, Setting, and ParticipantsRandomized intervention trial of 48 835 postmenopausal women in the United States who were of diverse backgrounds and ethnicities and participated in the Women's Health Initiative Dietary Modification Trial; 40% (19 541) were randomized to the intervention and 60% (29 294) to a control group. Study enrollment was between 1993 and 1998, and this analysis includes a mean follow-up of 7.5 years (through August 31, 2004).InterventionsThe intervention included group and individual sessions to promote a decrease in fat intake and increases in vegetable, fruit, and grain consumption and did not include weight loss or caloric restriction goals. The control group received diet-related education materials.Main Outcome MeasureChange in body weight from baseline to follow-up.ResultsWomen in the intervention group lost weight in the first year (mean of 2.2 kg, P<.001) and maintained lower weight than control women during an average 7.5 years of follow-up (difference, 1.9 kg, P<.001 at 1 year and 0.4 kg, P = .01 at 7.5 years). No tendency toward weight gain was observed in intervention group women overall or when stratified by age, ethnicity, or body mass index. Weight loss was greatest among women in either group who decreased their percentage of energy from fat. A similar but lesser trend was observed with increases in vegetable and fruit servings, and a nonsignificant trend toward weight loss occurred with increasing intake of fiber.ConclusionA low-fat eating pattern does not result in weight gain in postmenopausal women.Clinical Trial RegistrationClinicalTrials.gov Identifier: NCT00000611

Low-Fat dietary pattern and risk of invasive breast cancer: The women's health initiative randomized controlled dietary modification trial

Abstract: Despite a longstanding belief that a low-fat diet can reduce the risk of breast cancer, no controlled intervention trials have been reported. This randomized, controlled, primary prevention trial, based on the Women's Health Initiative cohort, enrolled 48,835 postmenopausal women 50 to 79 years of age at 40 U.S. clinical centers in the years 1993-2005. Forty percent of participants received a diet designed to lower the intake of total fat to 20% of energy, provide at least 5 servings daily of fruit and vegetables, and include at least 6 daily servings of grains. There was no explicit weight loss goal. The remaining 60% of women continued on their usual diets. The intervention group took part in an intensive behavioral modification program administered by a specially trained nutritionist. Participants received an individualized goal of total fat grams based on height and were trained to monitor their dietary intake. The comparison women were given informational materials, including dietary guidelines. At baseline, dietary and other variables, including body weight, were nearly identical in the intervention and control groups. Women in the diet group had a small decrease in energy consumption. The difference between groups in change from baseline in the percentage of energy from fat ranged from 10.7% after 12 months to 8.1% at year 6. The intervention group ate more fruits and vegetables, but there was less difference in grain consumption. The annualized incidence rate of invasive breast cancer during an average follow up of 8.1 years was 0.42% in the intervention group and 0.45% in the comparison group. The hazard ratio was 0.91% with a 95% confidence interval of 0.83 to 1.01. Rates of total cancer (excluding non-melanoma skin cancer), breast cancer mortality, and total mortality all were slightly lower for the intervention group, but the differences were not significant at the 0.05 level. Women who actively participated in the dietary intervention program and those consuming a high-fat diet at baseline had lower hazard ratios. The breast cancer risk also was lower in women with a relatively high baseline percentage of energy from fat. Tumor grade and size, lymph node status, and stage of breast cancers all were similar in the intervention and comparison groups. A lower hazard ratio was noted for progesterone receptor-negative tumors, but there was no apparent association with estrogen receptor status. A low-fat diet failed to lessen the risk of invasive breast cancer in this large trial of postmenopausal women during a follow up averaging approximately 8 years. Nevertheless, the trends observed, although not statistically significant, warrant longer-term studies. Any beneficial effects of reduced fat intake might take years to fully emerge.

Post-diagnosis weight gain and breast cancer recurrence in women with early stage breast cancer

Abstract: To examine whether weight gain after diagnosis of breast cancer affects the risk of breast cancer recurrence. Patients included 3215 women diagnosed with early stage breast cancer (Stage I > 1 cm., II, and IIIA) who were enrolled either in an observational cohort of breast cancer survivors or were part of the comparison group of a dietary intervention trial to prevent breast cancer recurrence. We computed weight change from 1 year prior to diagnosis to study enrollment. Delayed entry Cox proportional hazards models were used to evaluate associations of categories of weight change with time to recurrence, controlling for known prognostic factors. Neither moderate (5-10%) nor large (> 10%) weight gain (HR 0.8, 95% CI, 0.6-1.1; HR 0.9, 95% CI, 0.7-1.2, respectively) after breast cancer diagnosis was associated with an increased risk of breast cancer recurrence in the early years post-diagnosis (median time of 73.7 months from diagnosis). Our research provides evidence that weight gain commonly seen in the first several years following a breast cancer diagnosis does not increase a woman's risk for breast cancer recurrence in the first 5-7 years post-diagnosis. However, this research does not address the effects of weight gain on overall survival or on the risk of other new cancers, other prognostic outcomes of concern to the breast cancer survivor.

Development of a Glycemic Index Database for Food Frequency Questionnaires Used in Epidemiologic Studies

Abstract: Consumption of foods with a high glycemic index (GI) or glycemic load (GL) is hypothesized to contribute to insulin resistance, which is associated with increased risk of diabetes mellitus, obesity, cardiovascular disease, and some cancers. However, dietary assessment of GI and GL is difficult because values are not included in standard food composition databases. Our objective was to develop a database of GI and GL values that could be integrated into an existing dietary database used for the analysis of FFQ. Food GI values were obtained from published human experimental studies or imputed from foods with a similar carbohydrate and fiber content. We then applied the values to the Women's Health Initiative (WHI) FFQ database and tested the output in a random sample of previously completed WHI FFQs. Of the 122 FFQ line items (disaggregated into 350 foods), 83% had sufficient carbohydrate (>5 g/serving) for receipt of GI and GL values. The foods on the FFQ food list with the highest GL were fried breads, potatoes, pastries, pasta, and soft drinks. The fiber content of foods had very little influence on calculated GI or GL estimates. The augmentation of this FFQ database with GI and GL values will enable etiologic investigations of GI and GL with numerous disease outcomes in the WHI and other epidemiologic studies that utilize this FFQ.

Validity and Systematic Error in Measuring Carotenoid Consumption with Dietary Self-report Instruments

Abstract: Vegetables and fruits are rich in carotenoids, a group of compounds thought to protect against cancer. Studies of diet-disease associations need valid and reliable instruments for measuring dietary intake. The authors present a measurement error model to estimate the validity (defined as correlation between self-reported intake and "true" intake), systematic error, and reliability of two self-report dietary assessment methods. Carotenoid exposure is measured by repeated 24-hour recalls, a food frequency questionnaire (FFQ), and a plasma marker. The model is applied to 1,013 participants assigned between 1995 and 2000 to the nonintervention arm of the Women's Healthy Eating and Living Study, a randomized trial assessing the impact of a low-fat, high-vegetable/fruit/fiber diet on preventing new breast cancer events. Diagnostics including graphs are used to assess the goodness of fit. The validity of the instruments was 0.44 for the 24-hour recalls and 0.39 for the FFQ. Systematic error accounted for over 22% and 50% of measurement error variance for the 24-hour recalls and FFQ, respectively. The use of either self-report method alone in diet-disease studies could lead to substantial bias and error. Multiple methods of dietary assessment may provide more accurate estimates of true dietary intake.

Fruit and vegetable consumption of older Mexican-American women is associated with their acculturation level.

Abstract: Little is known about the association between acculturation and fruit and vegetable (FV) consumption among older Mexican-American (MA) women. Environmental and lifestyles changes experienced by immigrants to the United States may markedly affect their diet and health and increase their risk for chronic diseases. Our objectives were to: 1) describe FV consumption by ethnicity, acculturation, and sociodemographic characteristics, and 2) compare effects of acculturation and sociodemographic variables on FV intake in a population of older MA and non-Hispanic White (NHW) women from the Well-Integrat-ed Screening and Evaluation for Women Across the Nation (WISEWOMAN) Study. This report examines baseline FV intake of 346 underinsured women aged 50-76 years, assessed through 24-hour dietary recalls. Acculturation was measured with a five-item Likert-type scale. Twenty percent of more acculturated MA women, 24% of less acculturated MA women, and 36% of White women consumed > or = 5 servings of FV servings per day. Fruit and vegetable (FV) intake was associated with acculturation, education, and smoking status. Being more acculturated was associated with lower consumption of FVs among MAs, while having a higher education and no smoking was associated with higher intakes of FV servings among NHWs. Public health efforts to improve the intake of FVs among MA women should be sensitive to their acculturation status.

Increases in plasma carotenoid concentrations in response to a major dietary change in the women's healthy eating and living study.

Abstract: Background: Cohort studies suggest that higher circulating carotenoid concentrations through food sources may reduce breast cancer events. Other intervention studies have not achieved the level of change in circulating carotenoids required to properly test this hypothesis. Methods: In a randomized trial of 2,922 breast cancer survivors, we examined blood and self-reported diet at baseline and 1 year. Intensive telephone counseling encouraged a plant-based diet in the intervention group. Diet was measured via 24-hour recalls, and a panel of plasma carotenoid concentrations was assessed at both time points. Results: The study intervention was associated with a 51% increase in total carotenoid concentration, from 2.272 ± 1.294 to 3.440 ± 2.320 μmol/L, achieved mainly by marked increases in targeted carotenoids: α-carotene, β-carotene, and lutein. For each of these targeted carotenoids, the proportion of the intervention sample remaining below the cutpoint for the lowest baseline quartile decreased by one third to one half. After 1 year of study, half of the intervention group was in the highest baseline quartile. No change in distribution was observed in comparison group. Intervention participants achieved this change by both dietary pattern and vegetable juice consumption. Participants who chose to change dietary pattern without consuming significant quantities of vegetable juice achieved 75% of the level of change observed in other intervention participants. Conclusions: Innovative telephone counseling intervention and dietary targets in the Women's Healthy Eating and Living study were associated with the level of change in circulating carotenoid concentration necessary to test the diet and breast cancer hypothesis suggested by cohort studies. (Cancer Epidemiol Biomarkers Prev 2006;15(10):1886–92)

Controlled environments for production of value-added food crops with high phytochemical concentrations : Lycopene in tomato as an example

Abstract: Summary. Plants produce various phytochemicals that are of nutritional and medicinal value to humans. Phytochemicals having antioxidant capacity are drawing increased interest from consumers. Population studies among Americans have consistently demonstrated inadequate consumption of fruit and vegetables. Improving intake of fruit and vegetables has been a major public health effort for many years with minimal success. Given this, it seems opportunistic to consider other approaches to enhance the nutritional quality of the American diet. One plausible approach is the development of fresh produce containing a greater concentration of phytochemicals known to improve health, thus while consuming fewer servings of produce, Americans would still have significant exposure to health-promoting food constituents. Controlled environments provide a unique opportunity to modify the concentrations of selected phytochemicals in fruit and vegetables, yet practical information is limited regarding methods effective in optimizing antioxidant capacity. Our research at the University of Arizona Controlled Environment Agriculture Program has shown that application of moderate salt stress to tomato plants can enhance lycopene and potentially other antioxidant concentrations in fruit. The increase in lycopene in response to salt stress in the tomato fruit was shown to be cultivar specific, varying from 34% to 85%. Although the specific biological mechanisms involved in increasing fruit lycopene deposition has not been clearly elucidated, evidence suggests that increasing antioxidant concentrations is a primary physiological response of the plant to the salt stress. Another experiment showed that low temperature during postharvest increased antioxidant capacity of tomato fruit while it maintained the lycopene concentration. More detailed study in this area is needed including accumulation of antioxidant phytochemicals as affected by environmental conditions during the cultivation and the postharvest. of greenhouse tomato available in U.S. retail markets has increased dramatically during the past decade and now accounts for 37% of the weekly quantity of tomatoes sold in the average U.S. supermarket in 2003 (Cook and Calvin, 2005), where this quantity included produce imported from Mexico and Canada. This suggests that greenhouse tomatoes are preferred in retail sales likely due to the consistent supply and generally higher quality than field grown tomatoes. This trend seems driving neighboring countries more into greenhouse production.

Human serum contains detectable levels of the Hsp70 cochaperone HspBP1 and antibodies bound to HspBP1.

Abstract: The identification of the proteins that comprise the serum proteome is a current major research goal that will provide useful information for the diagnosis and treatment of various diseases. It is well established that Hsp70 and Hsp70 antibodies are present in human serum. This study reports on the development of an ELISA assay for the Hsp70 co-chaperone, HspBP1. HspBP1 is present in human serum at concentrations ranging between 0.74 to 3.98 ng/mL. No gender or age differences in the HspBP1 levels were identified. It was also found that human serum contained antibodies to HspBP1, and there were no gender or age differences in these levels. In addition, there was no correlation between the level of HspBP1 in a sample and the antibody titer. Finally, we found that HspBP1 in serum is complexed to anti-HspBP1 antibodies. This report provides initial baseline data on HspBP1 in human serum and provides the methods for future studies to determine if these levels are altered in response to disease.