Pilot randomized trial demonstrating reversal of obesity-related abnormalities in reward system responsivity to food cues with a behavioral intervention

OBJECTIVES

Obesity is associated with hyperactivation of the reward system for high-calorie (HC) versus low-calorie (LC) food cues, which encourages unhealthy food selection and overeating. However, the extent to which this hyperactivation can be reversed is uncertain, and to date there has been no demonstration of changes by behavioral intervention.

SUBJECTS AND METHODS

We used functional magnetic resonance imaging to measure changes in activation of the striatum for food images at baseline and 6 months in a pilot study of 13 overweight or obese adults randomized to a control group or a novel weight-loss intervention.

RESULTS

Compared to controls, intervention participants achieved significant weight loss (-6.3±1.0 kg versus +2.1±1.1 kg, P<0.001) and had increased activation for LC food images with a composition consistent with that recommended in the behavioral intervention at 6 months versus baseline in the right ventral putamen (P=0.04), decreased activation for HC images of typically consumed foods in the left dorsal putamen (P=0.01). There was also a large significant shift in relative activation favoring LC versus HC foods in both regions (P<0.04).

CONCLUSIONS

This study provides the first demonstration of a positive shift in activation of the reward system toward healthy versus unhealthy food cues in a behavioral intervention, suggesting new avenues to enhance behavioral treatments of obesity.

Impact of a home-based physical activity intervention upon exercise behaviors and anthropometric measures in women undergoing treatment for early stage breast cancer

Abstract #1117

Women who gain weight after breast cancer diagnosis have a worse prognosis compared to women who avoid weight gain. Weight gain is especially common in women treated with adjuvant chemotherapy, many of whom develop sarcopenic obesity which involves an increase in body fat and loss of lean muscle mass. This type of weight gain has been associated with increases in insulin and other metabolic hormones linked to breast cancer risk and prognosis. Studies have demonstrated that weight gain in breast cancer patients occurs, at least in part, due to decreases in physical activity during and after treatment.&#x2028; Methods: In this single arm pilot study, sedentary women with early stage breast cancer participated in a home-based exercise intervention during adjuvant chemotherapy and/or radiation. The target activity goal was 150 minutes of aerobic exercise per week. Participants underwent evaluation of anthropometric measures, fitness (measured by modified Bruce ramp protocol treadmill test), fatigue and quality of life at baseline and after the 12 week intervention. Change in these measures over time was assessed using Wilcoxon signed rank test of the change scores (post-pre values).&#x2028; Results: Forty-one women were enrolled in the study and 33 (80%) completed the 12 week protocol. Average age of participants was 47, and women were an average of 4.5 months from diagnosis at the time of enrollment. All but one of the women (98%) received adjuvant or neoadjuvant chemotherapy. Baseline and week 12 values for study variables are presented in table 1. Participants were sedentary at baseline, engaging in an average of 13 minutes of weekly activity. Physical activity increased significantly during the study period, with participants averaging 105 minutes of activity per week. Participants avoided weight gain and increases in body fat over the course of the study, and experienced significant improvements in fitness, quality of life and fatigue scores.&#x2028; &#x2028; Discussion: Women who completed a 12-week home-based exercise intervention during adjuvant therapy significantly increased activity and avoided weight gain, which has been associated with poor prognosis in early stage breast cancer. This trial, in conjunction with other exercise studies in breast cancer patients, provides preliminary data to help guide the design of randomized trials examining the impact of exercise upon breast cancer outcomes.

Citation Information: Cancer Res 2009;69(2 Suppl):Abstract nr 1117.

Impact of physical activity on insulin levels in breast cancer survivors

555

Background: Accumulating data suggest that body weight and physical activity may affect breast cancer risk and outcomes. Biological mechanisms underlying these relationships are not clear. Studies have demonstrated that high levels of insulin, often seen in obese and sedentary individuals, are also associated with an increased risk of breast cancer recurrence and breast cancer-related death. We sought to analyze whether exercise lowers insulin levels in a population of breast cancer survivors. Methods: Inactive women with early stage breast cancer who had completed adjuvant treatment were randomized to a 16 week, mixed cardiovascular and strength training exercise intervention, or to a normal care control group. Target exercise goals included 2 supervised strength training sessions and 90 minutes of unsupervised cardiovascular exercise each week. Fasting insulin and glucose levels, as well as measurement of weight, body composition, and circumference at the waist and hip, were collected at baseline and after 16 weeks in both groups, and changes in these measures were assessed. Results: One hundred and one women were randomized. Comparison of changes in anthropometric measures are presented in Table 1 . Baseline insulin levels were similar in the 2 groups. After the 16-week exercise or control period, insulin levels decreased by 2.86 μIU/ml in the exercise group (p=0.03), and by 0.27 μIU/ml in the control group (p=0.65). A comparison of the change in insulin levels across time in the 2 groups approached statistical significance (p=0.07). There was also a trend toward improvements in insulin sensitivity in the exercise group (p=0.09), with no change seen in fasting glucose levels. Conclusions: Physical activity was associated with a decrease in insulin levels and in hip circumference in breast cancer survivors. The relationship between physical activity and breast cancer prognosis may be mediated, at least partially, through changes in insulin levels and/or changes in fat mass or deposition.

[Table: see text]

No significant financial relationships to disclose.

The impact of an exercise intervention on body composition, fat distribution, and weight in breast cancer survivors

590

Background: Recent research has demonstrated that obesity increases a woman’s risk of breast cancer recurrence. Although the mechanism is not well understood, it is known that obese women have higher levels of insulin and other hormones related to energy balance. In this study, we sought to explore the impact of an exercise intervention on body composition, fat distribution, weight, and insulin levels in a population of breast cancer survivors. Methods: Inactive women with early stage breast cancer who had completed adjuvant chemotherapy and/or radiation were randomized to a 16-week exercise intervention or a normal care control group. The exercise intervention consisted of supervised strength training and unsupervised cardiovascular exercise, with a goal of 2 strength training sessions and 90 minutes of cardiovascular exercise each week. Measurement of weight, body composition, and circumference at the waist and hip, were collected at baseline and after 16 weeks in both groups. Fasting blood samples were also collected at these two time points for insulin and glucose levels, so that changes in these levels between the intervention and control groups could be compared. Results: Eighty-five women have been randomized; complete anthropometric data are presently available for 51. Women in the exercise group experienced a nonsignificant decrease in body weight, body fat, and circumference at the waist and hip, as compared to control patients. Participants completed a median of 84% of scheduled strength training sessions and 80% of recommended cardiovascular sessions. Strength increased by an average of 40% during the exercise intervention. Prior studies have demonstrated significant inter-assay variability in biomarker testing, thus insulin and glucose testing will be performed when all patients have completed the protocol. Conclusions: Compliance with the exercise intervention was good. Women in the exercise group experienced non-significant changes in anthropometric measures, and increased strength during the 16-week intervention. Final strength and anthropometric data from the entire cohort will be available for presentation. This project was supported by an ASCO Career Development Award and funding from the Lance Armstrong Foundation.

No significant financial relationships to disclose.