Randomized Controlled Trial of Aerobic Exercise on Insulin and Insulin-like Growth Factors in Breast Cancer Survivors: The Yale Exercise and Survivorship Study

• Published in: Cancer epidemiology, biomarkers & prevention Vol. 18; no. 1; pp. 306 - 313
• Main Authors: IRWIN, Melinda L, VARMA, Katie, ALVAREZ-REEVES, Marty, CADMUS, Lisa, WILEY, Andrew, CHUNG, Gina G, DIPIETRO, Loretta, MAYNE, Susan T, YU, Herbert
• Format: Journal Article
• Language: English
• Published: Philadelphia, PA American Association for Cancer Research 01.01.2009
• Subjects: Absorptiometry, Photon; Anthropometry; Biological and medical sciences; Bone Density; Breast Neoplasms - blood; c-peptide; Chi-Square Distribution; death; diabetes; Enzyme-Linked Immunosorbent Assay; Exercise; Female; fitness; glucose; Gynecology. Andrology. Obstetrics; Humans; Insulin - metabolism; Insulin-Like Growth Factor Binding Protein 3 - blood; Linear Models; Mammary gland diseases; Medical sciences; Middle Aged; obesity; physical activity; recurrence; Risk; Somatomedins - metabolism; Surveys and Questionnaires; survival; Survivors; Tumors; weight; United States; North America; America; Connecticut; Physical exercise; Breast disease; Survivor; Breast cancer; Malignant tumor; Randomized controlled trial; Mammary gland diseases; Insulin like growth factor; Randomization; Cancerology; Clinical trial; Mammary gland; Cancer
• ISSN: 1055-9965; 1538-7755
• DOI: 10.1158/1055-9965.EPI-08-0531

Background: High insulin and insulin-like growth factor-I (IGF-I) levels may be associated with an increased breast cancer risk and/or death. Given the need to identify modifiable factors that decrease insulin, IGF-I, and breast cancer risk and death, we investigated the effects of a 6-month randomized controlled aerobic exercise intervention versus usual care on fasting insulin, IGF-I, and its binding protein (IGFBP-3) in postmenopausal breast cancer survivors. Methods: Seventy-five postmenopausal breast cancer survivors were identified from the Yale-New Haven Hospital Tumor Registry and randomly assigned to an exercise ( n = 37) or usual care ( n = 38) group. The exercise group participated in 150 minutes per week of moderate-intensity aerobic exercise. The usual care group was instructed to maintain their current physical activity level. A fasting blood sample was collected on each study participant at baseline and 6 months. Blood levels of insulin and IGF were measured with ELISA. Results: On average, exercisers increased aerobic exercise by 129 minutes per week compared with 45 minutes per week among usual care participants ( P < 0.001). Women randomized to exercise experienced decreases in insulin, IGF-I, and IGFBP-3, whereas women randomized to usual care had increases in these hormones. Between-group differences in insulin, IGF-I, and IGFBP-3 were 20.7% ( P = 0.089), 8.9% ( P = 0.026), and 7.9% ( P = 0.006), respectively. Conclusions: Moderate-intensity aerobic exercise, such as brisk walking, decreases IGF-I and IGFBP-3. The exercise-induced decreases in IGF may mediate the observed association between higher levels of physical activity and improved survival in women diagnosed with breast cancer. (Cancer Epidemiol Biomarkers Prev 2009;18(1):306–13)