Faculty Bibliography

IGF-I shares structural homology and in vitro metabolic activity with insulin. Laboratory models suggest that IGF-I and its binding proteins IGFBP-1 and IGFBP-2 have potentially beneficial effects on diabetes risk, whereas IGFBP-3 may have adverse effects. We therefore conducted a prospective nested case-control investigation of incident diabetes (n = 742 case subjects matched 1:1 to control subjects) and its associations with IGF-axis protein levels in the Nurses' Health Study, a cohort of middle-aged women. The median time to diabetes was 9 years. Statistical analyses were adjusted for multiple risk factors, including insulin and C-reactive protein. Diabetes risk was fivefold lower among women with baseline IGFBP-2 levels in the top versus bottom quintile (odds ratio [OR](q5-q1) = 0.17 [95% CI 0.08-0.35]; P trend < 0.0001) and was also negatively associated with IGFBP-1 levels (OR(q5-q1) = 0.37 [0.18-0.73]; P trend = 0.0009). IGFBP-3 was positively associated with diabetes (OR(q5-q1) = 2.05 [1.20-3.51]; P trend = 0.002). Diabetes was not associated with total IGF-I levels, but free IGF-I and diabetes had a significant association that varied (P interaction = 0.003) by insulin levels above the median (OR(q5-q1) = 0.48 [0.26-0.90]; P trend = 0.0001) versus below the median (OR(q5-q1) = 2.52 [1.05-6.06]; P trend < 0.05). Thus, this prospective study found strong associations of incident diabetes with baseline levels of three IGFBPs and free IGF-I, consistent with hypotheses that the IGF axis might influence diabetes risk.

Obese and underweight women who develop breast cancer may have poorer survival compared with normal-weight women. However, the optimal weight for best prognosis is still under study. We conducted a prospective investigation of pre-diagnosis body mass index (BMI) and mortality among 14,948 breast cancer patients in the After Breast Cancer Pooling Project. Breast cancer patients diagnosed from 1990 to 2006 with AJCC Stage I-III breast tumors were drawn from four prospective cohorts. Hazard ratios (HR) and 95% confidence intervals (CI) representing the associations of BMI categories (World Health Organization international classifications) with recurrence and mortality were estimated using delayed entry Cox proportional hazards models. Obese (30 to < 35 kg/m(2)), severely obese (35 to < 40 kg/m(2)), and morbidly obese (>/= 40 kg/m(2)) were examined. After a mean follow-up of 7.8 years, 2,140 deaths and 2,065 recurrences were documented. Both underweight (HR = 1.59; 95% CI: 1.18, 2.13) and morbidly obese women (HR = 1.81; 95% CI: 1.42, 2.32) had the greatest risk of overall mortality compared with normal weight (18.5-24.9 kg/m(2)) women. Severe obesity (HR = 1.09; 95% CI: 0.88, 1.36) and obesity (HR = 1.11; 95% CI: 0.97, 1.27) were related to small non-significant increased risks. Overweight (25.0-29.9 kg/m(2)) was not associated with any excess risk compared with normal weight. Similar associations were found for breast cancer death and non-breast cancer death but not recurrence. Women who were underweight and morbidly obese before breast cancer diagnosis were at the greatest risk of all-cause mortality. Morbidly obese women were also at increased risk of death from breast cancer. These results suggest that degree of obesity confers differential risk on survival.

The 2008 Physical Activity (PA) Guidelines recommend engaging in at least 2.5 h (10 MET-hours/week) of moderate intensity PA per week (defined as 4 METs) to reduce risk of morbidity and mortality. This analysis was conducted to investigate whether this recommendation can be extended to breast cancer survivors. Data from four studies of breast cancer survivors measuring recreational PA from semi-quantitative questionnaires a median of 23 months post-diagnosis (interquartile range 18-32 months) were pooled in the After Breast Cancer Pooling Project (n = 13,302). Delayed entry Cox proportional hazards models were applied in data analysis with adjustment for age, post-diagnosis body mass index, race/ethnicity, menopausal status, TNM stage, cancer treatment, and smoking history. Engaging in at least 10 MET-hours/week of PA was associated with a 27% reduction in all-cause mortality (n = 1,468 events, Hazard Ratio (HR) = 0.73, 95% CI, 0.66-0.82) and a 25% reduction in breast cancer mortality (n = 971 events, HR = 0.75, 95% CI 0.65-0.85) compared with women who did not meet the PA Guidelines (<10 MET-hours/week). Risk of breast cancer recurrence (n = 1,421 events) was not associated with meeting the PA Guidelines (HR = 0.96, 95% CI, 0.86-1.06). These data suggest that adhering to the PA guidelines may be an important intervention target for reducing mortality among breast cancer survivors.

BACKGROUND: Self-report of dietary energy and protein intakes has been shown to be systematically and differentially underreported. OBJECTIVE: We assessed and compared the association of diabetes among postmenopausal women with biomarker-calibrated and uncalibrated dietary energy and protein intakes from food-frequency questionnaires (FFQs). DESIGN: The analyses were performed for 74,155 participants of various race-ethnicities from the Women's Health Initiative. Uncalibrated and calibrated energy and protein intakes from FFQs were assessed for associations with incident diabetes by using HR estimates based on Cox regression. RESULTS: A 20% increment in uncalibrated energy consumption was associated with increased diabetes risk (HR) of 1.03 (95% CI: 1.01, 1.05), 2.41 (95% CI: 2.06, 2.82) with biomarker calibration, and 1.30 (95% CI: 0.96, 1.76) after adjustment for BMI. A 20% increment in uncalibrated protein (g/d) resulted in an HR of 1.05 (95% CI: 1.03, 1.07), 1.82 (95% CI: 1.56, 2.12) with calibration, and 1.16 (95% CI: 1.05, 1.28) with adjustment for BMI. A 20% increment in uncalibrated protein density (% of energy from protein) resulted in an HR of 1.13 (95% CI: 1.09, 1.17), 1.01 (95% CI: 0.75, 1.37) with calibration, and 1.19 (95% CI: 1.07, 1.32) with adjustment for BMI. CONCLUSIONS: Higher protein and total energy intakes (calibrated) appear to be associated with a substantially increased diabetes risk that may be mediated by an increase in body mass over time. Diet-disease associations without correction of self-reported measurement error should be viewed with caution. This trial is registered at clinicaltrials.gov as NCT00000611.

CONTEXT: Oral contraceptive (OC) use is common, but bone changes associated with use of contemporary OC remain unclear. OBJECTIVE: The objective of the study was to compare bone mineral density (BMD) change in adolescent and young adult OC users and discontinuers of two estrogen doses, relative to nonusers. DESIGN AND SETTING: This was a prospective cohort study, Group Health Cooperative. PARTICIPANTS: Participants included 606 women aged 14-30 yr (50% adolescents aged 14-18 yr): 389 OC users [62% 30-35 mug ethinyl estradiol (EE)] and 217 age-similar nonusers; there were 172 OC discontinuers. The 24-month retention was 78%. MAIN OUTCOME MEASURE: The main outcome measure was BMD measured at 6-month intervals for 24-36 months. RESULTS: After 24 months, adolescents using 30-35 mug EE OCs, but not those using lower-dose OCs, had significantly smaller adjusted mean percentage BMD gains than nonusers at the spine [group means (95% confidence interval for between group differences) 1.32 vs. 2.26% (-1.89, -0.13%)] and whole body [1.45 vs. 2.03% (-1.29%, -0.13%)]. Adolescents who discontinued 30-35 mug EE OC showed significantly smaller gains than nonusers at the spine after 12 months [0.51 vs. 1.72% (-2.38%, -0.30%)]. Young adult OC users did not differ from nonusers. However, OC discontinuers of both doses differed significantly from nonusers at the spine 12 months after discontinuation [-1.32% < 30 mug EE, -0.92% 30-35 mug EE vs. +0.27% nonusers (-2.48, -0.54, and -1.94%, -0.55%, respectively)]. Results were similar for mean absolute BMD change (grams per square centimeter). CONCLUSIONS: Both OC use and discontinuation were associated with BMD losses/smaller gains relative to nonusers (differences < 2% after 12-24 months for all skeletal sites). The clinical significance of these results regarding future fracture risk is unknown. Study of longer-term trends after discontinuation is needed.

With aging, renal function tends to decline, as evidenced by reduced glomerular filtration rate. High-protein intake may further stress the kidneys by causing sustained hyperfiltration. To investigate whether dietary protein is associated with impaired renal function, we used data from 2 nested case-control studies within the Women's Health Initiative Observational Study (n = 2419). We estimated protein intake using a FFQ and estimated glomerular filtration rate (eGFR) from cystatin C. To account for the original study designs, inverse probability weights were applied. Self-reported energy and protein were calibrated using biomarkers of energy and protein intake. Associations between protein intake and renal function were estimated by weighted linear and logistic regression models. Average calibrated protein intake (mean +/- SD) was 1.1 +/- 0.2 g/(kg body weight.d).Twelve percent (n = 292) of women had impaired renal function. The odds of impaired renal function, defined as eGFR <60 mL/(min.1.73m(2)), was not associated with calibrated protein intake. When eGFR was modeled continuously, there was no association with calibrated protein when protein was expressed in absolute (g/d) or relative to energy (protein % energy/d), but protein relative to body weight [g/(kg body weight.d)] was associated with higher eGFR. There was no evidence for effect modification by age, BMI, or general health status. These data suggest higher protein intake is not associated with impaired renal function among postmenopausal women without a diagnosis of chronic kidney disease.

Epidemiologic studies addressing the association of alcohol consumption with breast cancer consistently suggest a modest association and a dose-response relationship. The epidemiologic evidence does not point to a single mechanism to explain the association, and several mechanisms have been proposed. Alcohol consumption is shown to increase levels of endogenous estrogens, known risk factors for breast cancer. This hypothesis is further supported by data showing that the alcohol-breast cancer association is limited to women with estrogen-receptor positive tumors. Products of alcohol metabolism are known to be toxic and are hypothesized to cause DNA modifications that lead to cancer. Recent research has focused on genes that influence the rate of alcohol metabolism, with genes that raise blood concentrations of acetaldehyde hypothesized to heighten breast cancer risk. Mounting evidence suggests that antioxidant intake(e.g.folate)mayreducealcohol-associatedbreast cancer risk, because it neutralizes reactive oxygen species, a second-stage product of alcohol metabolism. Diets lacking sufficient antioxidant intake, as a result, may further elevate the risk of breast cancer among alcohol consumers. Given that alcohol consumption is increasing worldwide and especially among women in countries of rapid economic growth, a greater understanding of the mechanisms underlying the known alcohol-breast cancer association is warranted. Avoiding overconsumption of alcohol is recommended, especially for women with known risk factors for breast cancer.

Little is known about the effects of diet after breast cancer diagnosis on survival. We prospectively examined the relation between post-diagnosis dietary factors and breast cancer and all-cause survival in women with a history of invasive breast cancer diagnosed between 1987 and 1999 (at ages 20-79 years). Diet after breast cancer diagnosis was measured using a 126-item food frequency questionnaire. Among 4,441 women without a history of breast cancer recurrence prior to completing the questionnaire, 137 subsequently died from breast cancer within 7 years of enrollment. Hazard ratios (HR) and 95% confidence intervals (CI) were estimated for intake of macronutrients as well as selected micronutrients and food groups from Cox proportional hazards regression models. After adjustment for factors at diagnosis (age, state of residence, menopausal status, smoking, breast cancer stage, alcohol, history of hormone replacement therapy), interval between diagnosis and diet assessment, and at follow-up (energy intake, breast cancer treatment, body mass index, and physical activity), women in the highest compared to lowest quintile of intake of saturated fat and trans fat had a significantly higher risk of dying from any cause (HR = 1.41, 95% CI = 1.06-1.87, P trend = 0.03) for saturated fat; (HR = 1.78, 95% CI = 1.35-2.32, P trend = 0.01) for trans fat intake. Associations were similar, though did not achieve statistical significance, for breast cancer survival. This study suggests that lower intake of saturated and trans fat in the post-diagnosis diet is associated with improved survival after breast cancer diagnosis.

INTRODUCTION: Evidence has been inconsistent regarding the impact of social networks on survival after breast cancer diagnosis. We prospectively examined the relation between components of social integration and survival in a large cohort of breast cancer survivors. METHODS: Women (N=4,589) diagnosed with invasive breast cancer were recruited from a population-based, multi-center, case-control study. A median of 5.6 years (Interquartile Range 2.7-8.7) after breast cancer diagnosis, women completed a questionnaire on recent post-diagnosis social networks and other lifestyle factors. Social networks were measured using components of the Berkman-Syme Social Networks Index to create a measure of social connectedness. Based on a search of the National Death Index, 552 deaths (146 related to breast cancer) were identified. Adjusted hazard ratios (HR) and 95% confidence intervals (CI) were estimated using Cox proportional hazards regression. RESULTS: Higher scores on a composite measure of social connectedness as determined by the frequency of contacts with family and friends, attendance of religious services, and participation in community activities was associated with a 15-28% reduced risk of death from any cause (p-trend=0.02). Inverse trends were observed between all-cause mortality and frequency of attendance at religious services (p-trend=0.0001) and hours per week engaged in community activities (p-trend=0.0005). No material associations were identified between social networks and breast cancer-specific mortality. CONCLUSIONS: Engagement in activities outside the home was associated with lower overall mortality after breast cancer diagnosis.

OBJECTIVE: Effective dietary intervention strategies that can be widely disseminated and have the potential for sustainable dietary modifications are needed. The purpose of this study was to describe and evaluate the effectiveness of a telephone-based soy intervention. DESIGN: A randomized controlled trial comparing self-reported intake and serum measures of soy during a 1-year dietary soy (Soy) to fruit and vegetable (Placebo) intervention conducted in two of five arms from the Herbal Alternatives Trial between May 2001 and September 2004. SUBJECTS/SETTING: One hundred sixty-three peri- and postmenopausal women (mean age=52 years) consuming self-selected diets in the Pacific Northwest, United States. INTERVENTION: Five telephone contacts with a registered dietitian during a 12-month intervention with the goal to increase soy food consumption to two servings daily. MAIN OUTCOME MEASURES: Change from baseline in self-reported soy servings and serum isoflavone (daidzein and genistein) concentrations were estimated using analysis of variance and generalized estimating equations. Proportions of participants achieving the intervention goal were compared using chi(2) tests. RESULTS: Ninety-four percent (n=74) of participants in the Soy arm and 89% (n=75) in the Placebo arm completed the trial, and slightly more than one third (n=27) received five phone contacts. Mean (+/-standard deviation) intakes of soy were similar for the Soy and Placebo arms at baseline (0.6+/-1.0 vs 0.4+/-0.8 servings/day; P>0.05). At 12-month follow-up visit, mean+/-standard deviation servings of soy per day were 1.6+/-1.4 for the Soy intervention compared to 0.5+/-0.9 within the Placebo arm (P<0.001). There were concomitant increases in serum isoflavones at 3 and 6 months from baseline in the Soy arm only, with approximately twofold increases in both daidzein (mean=66.4 nmol/L, 95% confidence interval [CI]: 39.0 to 93.9 [mean 16.9 ng/mL, 95% CI: 9.9 to 23.8]) and genistein (mean=100.4 nmol/L, 95% CI: 60.9 to 139.9 [mean 27.1 ng/mL, 95% CI: 16.5 to 37.8]) concentrations. Mean weight changed by <1 kg during the 12-month period in each group and physical activity remained stable, suggesting that participants incorporated soy foods into their diet by substituting for non soy foods rather than adding them to their diet. CONCLUSIONS: A brief telephone-based intervention with a focused message delivered by a registered dietitian is a feasible approach for encouraging targeted dietary changes, such as an increase in soy intake among peri- and postmenopausal women.