Purpose: To evaluate cardiopulmonary function (as measured by peak oxygen consumption [VO(2peak)]) across the breast cancer continuum and its prognostic significance in women with metastatic disease.
Patients and methods: Patients with breast cancer representing four cross-sectional cohorts--that is, (1) before, (2) during, and (3) after adjuvant therapy for nonmetastatic disease, and (4) during therapy in metastatic disease--were studied. A cardiopulmonary exercise test (CPET) with expired gas analysis was used to assess VO(2peak). A Cox proportional hazards model was used to estimate the risk of death according to VO(2peak) category (< 15.4 v ≥ 15.4 mL · kg(-1) · min(-1)) with adjustment for clinical factors.
Results: A total of 248 women (age, 55 ± 8 years) completed a CPET. Mean VO(2peak) was 17.8 ± a standard deviation of 4.3 mL · kg(-1) · min(-1), the equivalent of 27% ± 17% below age-matched healthy sedentary women. For the entire cohort, 32% had a VO(2peak) less than 15.4 mL · kg(-1) · min(-1)--the VO(2peak) required for functional independence. VO(2peak) was significantly different across breast cancer cohorts for relative (mL · kg(-1) · min(-1)) and absolute (L · min(-1)) VO(2peak) (P = .017 and P < .001, respectively); VO(2peak) was lowest in women with metastatic disease. In patients with metastatic disease (n = 52), compared with patients achieving a VO(2peak) ≤ 1.09 L · min(-1), the adjusted hazard ratio for death was 0.32 (95% CI, 0.16 to 0.67, P = .002) for a VO(2peak) more than 1.09 L · min(-1).
Conclusion: Patients with breast cancer have marked impairment in VO(2peak) across the entire survivorship continuum. VO(2peak) may be an independent predictor of survival in metastatic disease.