Breast Cancer- And Metabolic-related Predictors Of Vo2peak Amongst Active Post-menopausal Women

Abstract

Peak oxygen consumption (VO2peak) is reported to be lower amongst breast cancer patients both during and after adjuvant treatment relative to healthy sedentary controls. It is not known whether this is attributable to direct effects of treatment or indirect effects on whole body metabolism and exercise behaviour. PURPOSE: To identify metabolic and breast cancer-related predictors of relative VO2peak amongst active post-menopausal women. METHODS: 10 subjects were selectively recruited to each of three groups: 1) breast cancer patients 3 weeks post chemotherapy (BC1); 2) breast cancer patients 1-3 years post chemotherapy and radiation (BC2); 3) healthy controls (CON). All women were 45-60 years, self-reported as post-menopausal and performing 390 min/week of moderate intensity aerobic exercise. Gas analysis measurements were made during rest, a maximal incremental treadmill test, and steady state exercise (60% VO2R). Univariate linear regressions were performed with adjustment for age and BMI. RESULTS: Group was a significant predictor (p=0.01), resulting in β coefficients of -7.5 and -2.5 mL/kg/min for BC1 and BC2 relative to CON. In BC1 and BC2 combined, receipt of non-anthracycline but not anthracycline-containing chemotherapy protocols relative to CON was predictive of a lower VO2peak (β=-8.8, p<0.01). The amount of moderate intensity exercise self-reported in the past month (hours/week) (β=1.5, p=0.03), and surrogates of cardiovascular function, including O2 pulse (ml/beat) during steady state exercise (β=1.7, p<0.01), and five-minute heart rate recovery (bpm) (β=0.3, p=0.03) were also significant predictors. Receipt of fluorouracil chemotherapy or trastuzumab treatments, resting heart rate, resting VO2, substrate utilization (RER) at rest and for moderate intensity exercise, time since last menstruation, and occurrence of chemotherapy-induced menopause were not significant predictors. CONCLUSION: Among post-menopausal women, receipt of chemotherapy for breast cancer, in particular non-anthracycline-containing protocols and more recent completion, are associated with lower VO2peak, but resting and exercise metabolic parameters are not. Better recent exercise behaviour and cardiovascular function are associated with higher VO2peak.