Abstract A10: Impact of exercise on body fat distribution in overweight and obese breast cancer survivors
Authors: Sweeney Frank C. , Stewart Christina F. , Lee Kyuwan , Sami Nathalie , Dieli-Conwright Christina M. 
Published: August 2018

Background: There are an estimated 3 million breast cancer survivors (BCS) in the United States alone. Within this population, body anthropometrics have been rigorously studied as potential prognostic factors for cancer occurrence, recurrence, and survivorship.  Specifically, increased android fat percentage has been associated with increased blood pressure, elevated blood glucose, high triglycerides, and low high-density lipoproteins, all of which play contributing roles in mortality and risk of breast cancer recurrence.  In addition, increased gynoid fat percentage has been linked with increased percentage of dense breast volume, one of the most well-studied risk factors for breast cancer occurrence.  Further to this, an elevated waist-to-hip ratio (WHR), or the ratio of android to gynoid fat distribution, has been correlated with two times the risk of all-cause mortality and four times the risk of breast cancer-specific mortality. Due to the relation to mortality and disease recurrence, it is important to devise nonpharmacologic strategies, such as exercise, to improve biomarkers of body fat distribution including gynoid and android fat percentage and WHR.

Purpose/Hypothesis:  The aim of this study was to determine the effects of a 16-week combined aerobic and resistance exercise intervention on body fat distribution in overweight/obese BCS. We hypothesized that overweight/obese BCS participating in a 16-week combined resistance and aerobic exercise intervention will experience: (1) a decrease in android and gynoid fat percentage and (2) a decrease in the WHR compared to those who did not participate in an exercise program.

Materials/Methods: Overweight/obese (BMI ≥25 kg/m2) women diagnosed with stage I-III breast cancer, within 6 months of completion of cancer-related treatment, were recruited to participate. BCS were randomized to the control (CON) or the exercise (EX) group. WHR was determined from waist and hip circumference assessments using a fabric tape measure. Android and gynoid fat percentage was measured from a whole-body scan using dual-energy x-ray absorptiometry. The EX group underwent supervised, progressive aerobic and resistance exercise sessions 3 times/week for 16 weeks. Aerobic exercise sessions included 30 minutes of exercise performed at 65-85% heart rate maximum. Resistance exercise sessions included 3 sets of 15 repetitions of 8 whole-body exercises, performed at 65-85% 1-repetition maximum. The CON group was asked to maintain their current level of activity. Independent t-tests, two-way repeated measures ANOVA and paired samples t-tests were used to examine the effects of the exercise program on android and gynoid fat percentage and WHR.

Results: On average, women were 52.99 ± 10.01 years old with a mean BMI = 29.52 ± 5.29 kg/m2. At baseline there were no significant group differences among the outcomes measures across groups (p &gt; 0.05). Post-intervention, the android fat percentage was not significantly different in the EX group (mean change 0.48 ± 2.35%) when compared to the CON group (mean change 0.29 ± 2.30%, p = 0.14).  Similarly, the WHR was not significantly different in the EX group (mean change -0.01 ± 0.04%) when compared to the CON group (mean change 0.00 ± 0.03%, p=0.58). However, there was a significant decrease in the gynoid fat percentage post-intervention in the EX group (mean change -1.11 ± 1.75%), when compared to the CON group (0.41 ± 1.58%; p = 0.00).

Conclusions: A 16-week combined aerobic and resistance exercise intervention reduced gynoid fat percentage in overweight and obese breast cancer survivors yet did not alter android fat percentage or WHR. Further studies are necessary to investigate the possible effects of exercise on body fat distribution and their association with breast cancer outcomes.

Citation Format: Frank C. Sweeney, Christina F. Stewart, Kyuwan Lee, Nathalie Sami, Christina M. Dieli-Conwright. Impact of exercise on body fat distribution in overweight and obese breast cancer survivors [abstract]. In: Proceedings of the AACR Special Conference: Advances in Breast Cancer Research; 2017 Oct 7-10; Hollywood, CA. Philadelphia (PA): AACR; Mol Cancer Res 2018;16(8_Suppl):Abstract nr A10.