The effect of a lifestyle intervention on fat infiltration in skeletal muscle among colorectal cancer survivors with cancer-related fatigue: a randomized controlled trial

Objective Reducing fat infiltration in skeletal muscle may potentially improve health outcomes, such as overall survival and cancer-related fatigue, among colorectal cancer (CRC) survivors. We investigated the effect of a person-centred lifestyle intervention on fat infiltration in skeletal muscle assessed with ultrasound echointensity among CRC survivors with cancer-related fatigue. Methods This secondary analysis of a parallel randomized controlled trial included stage I-III CRC survivors with cancer-related fatigue. The intervention comprised twelve lifestyle coaching sessions over six months to improve physical activity and dietary intake. The control group did not receive lifestyle coaching. Fat infiltration in the rectus femoris muscle, assessed using 8-bit B-mode ultrasound-derived echointensity (arbitrary units [a.u.]), and cancer-related fatigue, measured using the Functional Assessment of Chronic Illness Therapy Fatigue scale, were evaluated at baseline and six months. Mediation analysis explored whether fat infiltration in skeletal muscle mediates the intervention’s effect on cancer-related fatigue. Results We included 161 CRC survivors with cancer-related fatigue (64.1±10.9 years, 55.3% women), who were randomized to the intervention (n=80) or control group (n=81). The change in echointensity over time did not differ between the intervention and control group (Δ 2.21 a.u. 95%CI: -1.04; 5.46). Additionally, fat infiltration in skeletal muscle did not mediate the effect of the lifestyle intervention on cancer-related fatigue. Conclusions The lifestyle intervention had no effect on fat infiltration in the rectus femoris muscle among CRC survivors with cancer-related fatigue. Although no effect on skeletal muscle echointensity was observed in the present study, our findings demonstrate the feasibility of echointensity assessment in studies focusing on muscle quality and support its potential value for future research in this field.