Effects of Behavioral Weight Loss and Metformin on IGFs in Cancer Survivors: A Randomized Trial
Hsin‐Chieh Yeh, Nisa M. Maruthur, Nae‐Yuh Wang, Gerald J. Jerome, Arlene Dalcin, Eva Tseng, Karen White, Edgar R. Miller, Stephen P. Juraschek, Noel T. Mueller, Jeanne Charleston, Nowella Durkin, Ahmed Hassoon, Dina Lansey, Norma Kanarek, Michael A. Carducci, Lawrence J. Appel
Abstract
CONTEXT: Higher levels of insulin-like growth factor-1 (IGF-1) are associated with increased risk of cancers and higher mortality. Therapies that reduce IGF-1 have considerable appeal as means to prevent recurrence. DESIGN: Randomized, 3-parallel-arm controlled clinical trial. INTERVENTIONS AND OUTCOMES: Cancer survivors with overweight or obesity were randomized to (1) self-directed weight loss (comparison), (2) coach-directed weight loss, or (3) metformin treatment. Main outcomes were changes in IGF-1 and IGF-1:IGFBP3 molar ratio at 6 months. The trial duration was 12 months. RESULTS: Of the 121 randomized participants, 79% were women, 46% were African Americans, and the mean age was 60 years. At baseline, the average body mass index was 35 kg/m2; mean IGF-1 was 72.9 (SD, 21.7) ng/mL; and mean IGF1:IGFBP3 molar ratio was 0.17 (SD, 0.05). At 6 months, weight changes were -1.0% (P = 0.07), -4.2% (P < 0.0001), and -2.8% (P < 0.0001) in self-directed, coach-directed, and metformin groups, respectively. Compared with the self-directed group, participants in metformin had significant decreases on IGF-1 (mean difference in change: -5.50 ng/mL, P = 0.02) and IGF1:IGFBP3 molar ratio (mean difference in change: -0.0119, P = 0.011) at 3 months. The significant decrease of IGF-1 remained in participants with obesity at 6 months (mean difference in change: -7.2 ng/mL; 95% CI: -13.3 to -1.1), but not in participants with overweight (P for interaction = 0.045). There were no significant differences in changes between the coach-directed and self-directed groups. There were no differences in outcomes at 12 months. CONCLUSIONS: In cancer survivors with obesity, metformin may have a short-term effect on IGF-1 reduction that wanes over time.