Cardiorespiratory fitness in childhood cancer survivors: a systematic review and meta-analysis

Abstract

Aims Cardiovascular disease (CVD) is a leading cause of mortality in childhood cancer survivors (CCS) that may be related to the cardiotoxic effects of radiation or chemotherapy and concomitant reductions in cardiorespiratory fitness. Therefore, we sought to compare cardiorespiratory fitness (peak oxygen uptake, V̇O2peak) between CCS and age-matched non-cancer controls (CON). Secondary outcomes included haemodynamics and resting cardiac function. Methods and results Embase, Scopus, MEDLINE, CINAHL, and SPORTDiscus databases were searched from inception to June 2023 for eligible studies. Cross-sectional studies with V̇O2peak measured in CCS and CON were included. Differences in outcomes and pooled estimates for each outcome were estimated from a fixed-effects meta-analysis and between-group differences were reported as a weighted mean difference (WMD). Of 2026 studies identified, 18 reported V̇O2peak (CCS: n = 786, 44% female, mean age: 16 years, time post-therapy: 5.8 years; CON: n = 1379, 50% female, mean age: 16 years). V̇O2peak was lower in CCS [WMD: −7.08 mL/kg/min, 95% confidence interval (CI): −7.75 to −6.42, I 2: 79%, n = 2165] with no difference for peak exercise heart rate (WMD: −1.4 b.p.m., 95% CI: −3.0 to 0.2, I 2: 63%, n = 741). Resting left ventricular ejection fraction (WMD: −1.61%, 95% CI: −2.60 to −0.62, I 2: 49%, n = 222) and systolic blood pressure were lower (WMD: −3.8 mmHg, 95% CI: −5.7 to −1.9, I 2: 25%, n = 184) while resting heart rate was higher in CCS (WMD: 4.9 bpm; 95% CI: 1.8–7.9, I 2: 55%, n = 262). Conclusion Childhood cancer survivors have a marked reduction in cardiorespiratory fitness (7.1 mL/kg/min lower than CON) that may have important prognostic implications for their future risk of CVD and mortality.