Patient-reported outcomes predict survival and adverse events following anticancer treatment initiation in advanced HER2-positive breast cancer

Background: The prognostic value of patient-reported outcomes (PROs) has been minimally explored in advanced breast cancer (BC), and their comparative prognostic performance against Eastern Cooperative Oncology Group performance status (ECOG PS) is largely unknown. Patients and methods: This study pooled individual participant data from clinical trials CLEOPATRA, EMILIA, and MARIANNE. Pre-treatment PRO associations with overall survival (OS), progression-free survival (PFS), and grade ≥3 adverse events were evaluated via Cox proportional hazards regression. Prognostic performance was assessed with the C-statistic (c). PRO values were collected via the Functional Assessment of Cancer Therapy—Breast (FACT-B) questionnaire. All analyses were stratified by study and treatment arms. Analyses adjusted for known prognostic variables were conducted. Exploratory analysis of the prognostic performance of PROs compared to ECOG PS was undertaken. Results: The study included data from 2894 patients initiated on contemporary therapies including pertuzumab (n = 765), trastuzumab (n = 1173), trastuzumab emtansine (n = 1225), taxanes (n = 1173), lapatinib (n = 496), and capecitabine (n = 496). On univariable and adjusted analysis, patient-reported physical well-being, functional well-being, and BC subscale were all identified to be associated with OS, PFS, and grade ≥3 adverse events (P < 0.05). Patient-reported physical well-being was the most prognostic PRO for all assessed outcomes. The OS prognostic performance of physical well-being (c = 0.58) was superior to ECOG PS (c = 0.56) (P < 0.05), with multivariable analysis indicating that both provide independent information (P < 0.0001). Conclusions: PROs were identified as independent prognostic factors for OS, PFS, and grade ≥3 adverse events in patients with human epidermal growth factor receptor 2 (HER2)-positive advanced BC initiating contemporary treatment options. Further, patient-reported physical well-being was more prognostic of OS than ECOG PS and contained independent information. PROs have value as prognostic and stratification factors for clinical use and research trials of anticancer treatment in HER2-positive ABC.