# Increased Skeletal Muscle Fat in Patients With Haematological Cancer Is Associated With Reduced Cardiorespiratory Fitness

## TL;DR

Patients with blood cancer have more fat in their leg muscles, which is linked to worse heart and lung fitness.

## Contribution

This study is the first to show that increased skeletal muscle fat in haematological cancer patients is associated with reduced cardiorespiratory fitness.

## Key findings

- Haematological cancer patients had significantly higher thigh skeletal muscle fat fraction compared to healthy controls.
- Higher skeletal muscle fat fraction was a significant independent predictor of lower peak oxygen uptake (V̇O2peak).
- Haemoglobin concentrations also significantly predicted V̇O2peak, but other factors like muscle volume or heart strain did not.

## Abstract

Patients with haematological cancer often exhibit reduced cardiorespiratory fitness and an elevated risk of cardiovascular disease. The mechanisms underlying this impairment are multifactorial, but the contribution of skeletal muscle fat infiltration has not been evaluated. This study aimed to compare thigh skeletal muscle fat fraction (SMFF) in patients with haematological cancer to healthy controls and to assess the contribution of SMFF to cardiorespiratory fitness in this cohort.

We performed a cross‐sectional analysis of patients with haematological cancer (n = 70, 61% male, age: 51 ± 16 years) and age‐ and sex‐matched healthy controls (n = 70, 61% male, age: 50 ± 15 years). Thigh SMFF was assessed via magnetic resonance imaging. We also measured cardiorespiratory fitness (peak oxygen uptake, V̇O2peak), global longitudinal strain (GLS) via echocardiography and haemoglobin concentrations in the haematological cancer cohort. Hierarchical multiple regression analysis was performed to identify predictors of V̇O2peak.

SMFF was higher in the haematological cancer cohort versus the healthy control cohort (11.0% ± 3.4% vs. 8.8% ± 3.8%, p = 0.001). V̇O2peak was significantly lower than predicted values for the haematological cancer cohort (mean difference; 9.61 ± 8.30 mL.kg−1.min−1, p < 0.001). The multiple regression analysis accounted for 35% of the variance in V̇O2peak with both SMFF (β = −0.40, ΔR
2 = 0.14, p = 0.002) and haemoglobin concentrations (β = 0.50, ΔR
2 = 0.23, p < 0.001) being significant independent predictors of V̇O2peak, while skeletal muscle volume (β = 0.00, ΔR
2 = 0.00, p = 0.767), GLS (β = 0.06, ΔR
2 = 0.00, p = 0.509), prior anthracycline treatment (β = 0.00, ΔR
2 = 0.00, p = 0.962) and clinical diagnosis (β = 0.00, ΔR
2 = 0.00, p = 0.555) were not.

SMFF is increased in haematological cancer patients and contributes to reduced V̇O2peak. Consequently, increased SMFF may be an important target to improve cardiovascular health and cardiorespiratory fitness in this population.