Effects of Tai Chi Chuan on insulin and cytokine levels in a randomized controlled pilot study on breast cancer survivors

Abstract

Background: Tai Chi Chuan (TCC) is an integrative medicine mind-body practice with a physical activity component that has positive effects on aerobic capacity, muscular strength, and quality of life among cancer survivors, similar to the effects elicited by other modes of moderate-intensity exercise. Inflammatory cytokines and insulin and insulin-related signaling molecules may contribute to weight gain and affect cancer recurrence rates and survival; exercise can curb cancer- and treatment-related weight gain, increase survival, and reduce levels of insulin and inflammatory cytokines. Despite knowing the beneficial effects of conventional exercise interventions on these mediators, little is known about the physiologic effects of TCC on these pathways in breast cancer survivors.

Methods: We assessed the effects of a 12-week, moderately intense, TCC intervention (n = 9) compared with a non-physical activity control (n = 10) consisting of psychosocial support therapy (PST), on levels of insulin, insulin-like growth factor (IGF)-1, insulin growth factor-like binding protein (IGFBP)-1, IGFBP-3, and cytokines interleukin (IL)-6, IL-2, and interferon (IFN)-γ in breast cancer survivors.

Results: Levels of insulin are significantly different in TCC and PST groups; levels remained stable in the TCC group but increased in the PST control group (P = .099). Bivariate analysis revealed novel and significant correlations (all r > 0.45, all P ≤ .05) of both decreased fat mass and increased fat-free mass with increased IL-6 and decreased IL-2 levels.

Conclusions: This pilot study shows that TCC may be associated with maintenance of insulin levels and changes in cytokine levels that may be important for maintenance of lean body mass in breast cancer survivors.

Figure 1. Proposed model of the effects of a physical activity intervention on insulin, insulin-signaling molecules and cytokines

We hypothesize that IL-6 may contribute to inflammation-mediated cellular proliferation and ultimately tumor growth and increased recurrence risk in an environment of no physical activity (A). However, in the presence of an intervention with a physical activity and meditative component (e.g. TCC), increased levels of skeletal-muscle-derived IL-6 act in an anti-inflammatory manner and induce lipolysis leading to maintenance of a healthy weight and reduced risk of recurrence (B).

Figure 2

Figure 2A: Changes in mean insulin and insulin-related protein concentrations in TCC and PST groups Figure 2B: Changes in mean cytokines concentrations in TCC and PST groups

Figure 2

Figure 2A: Changes in mean insulin and insulin-related protein concentrations in TCC and PST groups Figure 2B: Changes in mean cytokines concentrations in TCC and PST groups

Figure 3

Relationships between changes in IGF-1, IGFBP-1, IFN-gamma and insulin.

Figure 4

Relationship between changes in cytokines IL-6 and IL-2 and fat mass and fat-free mass.