Abstract
BACKGROUND: Cardiorespiratory fitness (CRF) is reduced in cancer survivors and predicts cardiovascular disease (CVD)-related and all-cause mortality. However, routine measurement of CRF is not always feasible. OBJECTIVES: The purpose of this study was to identify clinical, cardiac biomarker, and imaging measures associated with reduced peak oxygen consumption (VO(2)peak) (measure of CRF) early post-breast cancer therapy to help inform CVD risk. METHODS: Consecutive women with early-stage HER2+ breast cancer receiving anthracyclines and trastuzumab were recruited prospectively. Within 6 ± 2 weeks of trastuzumab completion, we collected clinical information, systolic/diastolic echocardiographic measures, high-sensitivity troponin I, B-type natriuretic peptide, and VO(2)peak using a cycle ergometer. Regression models were used to examine the association between VO(2)peak and clinical, imaging, and cardiac biomarkers individually and in combination. RESULTS: Among 147 patients (age 52.2 ± 9.3 years), the mean VO(2)peak was 19.1 ± 5.0 mL O(2)·kg(-1)·min(-1) (84.2% ± 18.7% of predicted); 44% had a VO(2)peak below threshold for functional independence (<18 mL O(2)·kg(-1)·min(-1)). In multivariable analysis, absolute global longitudinal strain (GLS) (β = 0.58; P = 0.007), age per 10 years (β: -1.61; P = 0.001), and E/e' (measure of diastolic filling pressures) (β = -0.45; P = 0.038) were associated with VO(2)peak. GLS added incremental value in explaining the variability in VO(2)peak. The combination of age ≥50 years, E/e' ≥7.8, and GLS <18% identified a high probability (85.7%) of compromised functional independence, whereas age <50 years, E/e' <7.8, and GLS ≥18% identified a low probability (0%). High-sensitivity troponin I and B-type natriuretic peptide were not associated with VO(2)peak. CONCLUSIONS: Readily available clinical measures were associated with VO(2)peak early post-breast cancer therapy. A combination of these parameters had good discrimination to identify patients with compromised functional independence and potentially increased future CVD risk.