Abstract
BACKGROUND: Low muscle mass (MM) is a common component of cancer-related malnutrition and sarcopenia, conditions that are all independently associated with an increased risk of mortality. This study aimed to (1) compare the prevalence of low MM, malnutrition, and sarcopenia and their association with survival in adults with cancer from the UK Biobank and (2) explore the influence of different allometric scaling (height [m(2) ] or body mass index [BMI]) on low MM estimates. METHODS: Participants in the UK Biobank with a cancer diagnosis within 2 years of the baseline assessment were identified. Low MM was estimated by appendicular lean soft tissue (ALST) from bioelectrical impedance analysis derived fat-free mass. Malnutrition was determined using the Global Leadership in Malnutrition criteria. Sarcopenia was defined using the European Working Group on Sarcopenia in Older People criteria (version 2). All-cause mortality was determined from linked national mortality records. Cox-proportional hazards models were fitted to estimate the effect of low MM, malnutrition, and sarcopenia on all-cause mortality. RESULTS: In total, 4122 adults with cancer (59.8 ± 7.1 years; 49.2% male) were included. Prevalence of low MM (8.0% vs. 1.7%), malnutrition (11.2% vs. 6.2%), and sarcopenia (1.4% vs. 0.2%) was higher when MM was adjusted using ALST/BMI compared with ALST/height(2) , respectively. Low MM using ALST/BMI identified more cases in participants with obesity (low MM 56.3% vs. 0%; malnutrition 50% vs. 18.5%; sarcopenia 50% vs. 0%). During a median 11.2 (interquartile range: 10.2, 12.0) years of follow up, 901 (21.7%) of the 4122 participants died, and of these, 744 (82.6%) deaths were cancer-specific All conditions were associated with a higher hazard of mortality using either method of MM adjustment: low MM (ALST/height(2) : HR 1.9 [95% CI 1.3, 2.8], P = 0.001; ALST/BMI: HR 1.3 [95% CI 1.1, 1.7], P = 0.005; malnutrition (ALST/height(2) : HR 2.5 [95% CI 1.1, 1.7], P = 0.005; ALST/BMI: HR 1.3 [95% CI 1.1, 1.7], P = 0.005; sarcopenia (ALST/height(2) : HR 2.9 [95% CI 1.3, 6.5], P = 0.013; ALST/BMI: HR 1.6 [95% CI 1.0, 2.4], P = 0.037). CONCLUSIONS: In adults with cancer, malnutrition was more common than low MM or sarcopenia, although all conditions were associated with a higher mortality risk, regardless of the method of adjusting for MM. In contrast, adjustment of low MM for BMI identified more cases of low MM, malnutrition, and sarcopenia overall and in participants with obesity compared with height adjustment, suggesting it is the preferred adjustment.