Increased skeletal intermuscular fat is associated with reduced exercise capacity in cancer survivors: a...

Cancer survivors experience on average a 20% reduction in peak exercise capacity (VO_{2 peak}) post-cancer treatment. Intermuscular fat (IMF) is a strong predictor of reduced exercise capacity in heart failure (HF) patients; however it is unknown whether increased IMF is related to reduced VO_{2 peak} in cancer survivors.

Twenty eight individuals: 14 cancer survivors > 12-months post-cancer treatment and 14 individuals without cancer were matched on age, gender, and body mass index (BMI). Participants underwent magnetic resonance imaging (MRI) assessments of IMF within the paraspinal muscles, VO_{2 peak} and exercise-associated measures of left ventricular ejection fraction (LVEF). Blinded analyses were performed. Associations between the ratio of IMF to skeletal muscle (SM) were estimated using Pearson's partial correlation coefficients. Individuals with cancer and non-cancer comparators were of similar age (54 ± 17 versus 54 ± 15 years; p = 1.0), gender (5 men and 9 women, both groups), and BMI (27 ± 4 versus 26 ± 4; p = 0.57). Peak VO₂ was 22% lower in cancer survivors versus non-cancer comparators (26.9 vs 34.3 ml/kg/min; p = 0.005), and was correlated with IMF:SM in both cancer survivors and non-cancer individuals after accounting for exercise-associated LVEF, resting LVEF, BMI, other body fat depots, and cardiovascular disease (CVD) co-morbidities (p < 0.001 to 0.08 for all adjusted correlations).

Among cancer survivors that previously received anthracyclines, increased intermuscular fat is associated with reduced VO_{2 peak} even after accounting for exercise-associated cardiac function. This suggests IMF is important in the development of exercise intolerance, an outcome experienced by a large number of cancer survivors.