Exercise capacity in long-term survivors of pediatric cancer: an analysis from the Cardiac Risk Factors in Childhood Cancer Survivors Study.

BACKGROUND

Childhood cancer survivors may have premature symptomatic cardiovascular and non-cardiovascular diseases that contribute to reduced capacity for physical activity. Studies of exercise capacity and identification of risk factors for reduced capacity in survivors are limited.

PROCEDURE

We assessed maximal myocardial oxygen consumption (V(O(2)max), a measure of exercise capacity) in survivors at least 4 years after cancer diagnosis and sibling controls. We evaluated associations between V(O(2)max) and age, sex, treatments, cardiac structure and function, biomarkers, endocrine function, and physical activity.

RESULTS

Of 72 survivors (mean age, 22 years; range, 8.0-40 years) and 32 siblings (mean age, 20.2 years; range, 8-46 years), about half were male. Mean time since diagnosis was 13.4 years (range, 4.5-31.6 years). In age- and sibling-pair adjusted analyses, V(O(2)max) was lower in survivors than siblings (males, 28.53 vs. 30.90 ml/kg/minute, P = 0.08; females, 19.81 vs. 23.40 ml/kg/minute, P = 0.03). In males, older age (P = 0.01), higher percent body fat (P < 0.001) and high or low left ventricular (LV) mass Z-scores (P = 0.03) predicted lower V(O(2)max). In females, older age (P < 0.001), methotrexate exposure (P = 0.01), and higher, but normal, LV load-dependent contractility (P = 0.02) predicted lower V(O(2)max).

CONCLUSIONS

Fitness for most survivors and controls was poor and generally lower in survivors, particularly females. Older age, higher body fat, methotrexate exposure, and extremes of LV mass/function were associated with lower V(O(2)max) in survivors. Because physical activity can improve nutritional and cardiac conditions, survivors should be encouraged to exercise regularly with close monitoring.