Cardiorespiratory Fitness, Ventilatory Constraints, And Qualitative Aspects Of Dyspnea Among Breast Cancer Survivors With Obesity

PURPOSE: Breast cancer survivors may experience exercise intolerance due to deconditioning, but respiratory impairment also plays a role. Obesity itself is known to increase ventilatory constraints during exercise. Little is known about how obesity and breast cancer affect exercise tolerance. We evaluated cardiorespiratory fitness (CRF), ventilatory constraints, and qualitative aspects of dyspnea in breast cancer survivors with obesity. METHODS: Thirty-two patients (58.9 ± 8.9 yr, BMI: 34.8 ± 3.7 kg/m2) completed pulmonary function testing and maximal cardiopulmonary exercise testing. Expiratory flow limitation (EFL) was calculated as >35% overlap between tidal and maximal expiratory flow-volume loops. Dynamic hyperinflation was calculated as a > 150 mL decrease in inspiratory capacity from rest to exercise. Participants rated 15 descriptors of dyspnea on a scale of 0 to 10. Data are expressed as Mean ± SD and unpaired t-tests were used for analysis. RESULTS: 25% of participants had low CRF (VO2peak < 85% predicted). Dead space breathing (VD/VT) was higher among patients with low CRF (18.63 ± 1.51 vs. 14.92 ± 3.36; P = 0.0002). At peak exercise, 69% of participants experienced dynamic hyperinflation. Maximum expiratory pressure (%predicted) was lower among patients with dynamic hyperinflation vs. those without (69.8 ± 15.8 vs. 90.1 ± 25.9; P = 0.0102). Dyspnea descriptors including smothering, air hunger, and suffocation were rated higher among patients with dynamic hyperinflation vs. those without (P = 0.0107, P = 0.0170, and P = 0.0149, respectively). At peak exercise, 31% of participants experienced EFL. Forced expiratory volume in one second/forced vital capacity (FEV1/FVC) and mid expiratory flows (FEF25-75) were lower among patients with EFL vs. those without EFL (78.8 ± 2.67 vs. 82.7 ± 4.32%; P = 0.0140 and 99.1 ± 13.9 vs 121.7 ± 32.8%pred; P = 0.0102). CONCLUSIONS: 1 in 4 breast cancer survivors with obesity are deconditioned. Most patients experience ventilatory constraints during exercise, which could be due to lower expiratory muscle strength and lower mid expiratory flows. Exercise testing should be considered among patients with exercise intolerance or exertional dyspnea to help uncover factors that may be contributing to reduced CRF and tailor exercise prescriptions. Supported by: PELOTONIA GR130528, K12CA133250