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 (&lt; 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 &lt; .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.

Cardiopulmonary Function and Age-Related Decline Across the Breast Cancer Survivorship Continuum