ASPO Abstracts
Muscle strength and fasting insulin levels in overweight and obese breast cancer survivors
Category: Survivorship & Health Outcomes/Comparative Effectiveness Research, Lifestyles Behavior, Energy Balance & Chemoprevention
Conference Year: 2018
Abstract Body:
PURPOSE. Detrimental side effects of breast cancer treatments include weight gain, elevated fasting insulin levels, and reductions in muscle strength (MST). Elevated fasting insulin levels increase the anabolic protein, IGF- 1, which may lead to tumor production and cancer recurrence. MST has been inversely related to impaired glucose metabolism and subsequently insulin sensitivity. The purpose of this study was to determine whether fasting insulin levels are associated with MST in overweight or obese breast cancer survivors. METHODS. Sedentary, overweight/obese (BMI >25 kg/m2) breast cancer survivors (Stage I-III) who completed treatment within the previous 6 months were eligible for this study. Fasting serum insulin was measured using enzyme- linked immunoabsorbent assays. Maximal MST (1- repetition maximum, 1-RM) was estimated from 10-RM tests of the leg extension (LE), leg flexion (LF), chest press (CP), and latissimus pulldown (LP) to estimate 1-RM values. Pearson’s correlations were performed to examine the association between MST and fasting insulin levels. RESULTS. Our sample included 94 breast cancer survivors (mean age 53.0±10.4 years) with an average BMI of 33.5±5.5 kg/m2. Participants were diagnosed with predominantly Stage I (40%) and Stage 2 (38%) breast cancer and had undergone both chemotherapy and radiation (76%). Fasting insulin was 35.4±12.1 uU/mL, and 1-RM MST was 57.2±20.3 kg for LE, 47.5±12.9 kg for LF, 10.5±5.4 kg for CP, and 30.0±7.5 kg for LP. Significant correlations were found between insulin and MST for LE (r=-0.83, p=0.001), LF (r=-0.79, p=0.001), LP (r=-0.68, p=0.001), and CP (r=-0.71, p=0.01). CONCLUSION. Elevated fasting insulin levels were associated with weaker lower and upper body muscle strength in breast cancer survivors. These findings emphasize the clinical importance of assessing these measures post-diagnosis to better derive targeted strategies, such as prescribed exercise, that can concurrently improve insulin and muscle strength.
Keywords: Insulin, IGF-1, Breast Cancer Recurrence