Childhood Acute Lymphoblastic Leukemia Survivors Have a Substantially Lower Cardiorespiratory Fitness Level Than Healthy Canadians Despite a Clinically Equivalent Level of Physical Activity

Introduction: As the survival rate of childhood acute lymphoblastic leukemia (ALL) continues to improve, the physical deconditioning is becoming an increasingly common problem in survivors. The aim of this study was to compare the cardiorespiratory fitness and physical activity levels of survivors and control participants. Methods: A total of 221 childhood ALL survivors (114 males and 107 females), diagnosed between 1987 and 2010 and treated according to Dana Farber Cancer Institute-ALL 87-01 to 05-01 protocols at Sainte-Justine University Health Center (SJUHC), Montreal (Canada), and 825 control participants (364 males and 461 females), recruited in the Canadian Health Measures Survey (cycle 2) during 2009 to 2011 by Statistics Canada, were included in our analyses. In both survivors and controls, cardiorespiratory fitness and moderate to vigorous physical activity (MVPA) were assessed. Results: Survivors' V̇O₂ peak was found to be 22% lower than that of controls. Cardiorespiratory fitness was different between the survivors (32.4 ± 8.3 mL/(kg·min); β = 0.11; 95% confidence interval [CI] 0.07-0.14) and the controls (41.6 ± 9.4 mL/(kg·min); β = 0.16; 95% CI 0.13-0.18), despite a clinically equivalent level of MVPA [survivors (27.5 ± 27.4 min/day) and controls (33.4 ± 24.2 min/day)]. Status (being survivor) and the age of the participants were negatively associated with cardiorespiratory fitness, whereas MVPA and male gender were positively associated with cardiorespiratory fitness. Conclusion: We observed that for a clinically equivalent level of MVPA, cardiorespiratory fitness was significantly lower in survivors compared with controls. Our findings showed that female survivors were most affected, compared with male survivors. These findings allow further understanding of the physiological differences between childhood ALL survivors and control participants and have important implications for this high-risk population of survivors.