Few prognostic models for overall survival (OS) are available for patients with metastatic castration-resistant prostate cancer (mCRPC) treated with recently approved agents. We developed a prognostic index model using readily available clinical and laboratory factors from a phase III trial of abiraterone acetate (hereafter abiraterone) in combination with prednisone in post-docetaxel mCRPC.
Baseline data were available from 762 patients treated with abiraterone-prednisone. Factors were assessed for association with OS through a univariate Cox model and used in a multivariate Cox model with a stepwise procedure to identify those of significance. Data were validated using an independent, external, population-based cohort.
Six risk factors individually associated with poor prognosis were included in the final model: lactate dehydrogenase>upper limit of normal (ULN) (hazard ratio [HR]=2. 31), Eastern Cooperative Oncology Group performance status of 2 (HR=2. 19), presence of liver metastases (HR=2. 00), albumin≤4 g/dl (HR=1. 54), alkaline phosphatase>ULN (HR=1. 38) and time from start of initial androgen-deprivation therapy to start of treatment≤36 months (HR=1. 30). Patients were categorized into good (n=369, 46%), intermediate (n=321, 40%) and poor (n=107, 13%) prognosis groups based on number of risk factors and relative HRs. The C-index was 0. 70±0. 014. The model was validated by the external dataset (n=286).
This analysis identified six factors used to model survival in mCRPC and categorized patients into three distinct risk groups. Prognostic stratification with this model could assist clinical practice decisions for follow-up and monitoring, and may aid in clinical trial design.
Annals of oncology : official journal of the European Society for Medical Oncology / ESMO. 2015 Dec 18 [Epub ahead of print]
K N Chi, T Kheoh, C J Ryan, A Molina, J Bellmunt, N J Vogelzang, D E Rathkopf, K Fizazi, P W Kantoff, J Li, A A Azad, B J Eigl, D Y C Heng, A M Joshua, J S de Bono, H I Scher
Department of Medical Oncology, BC Cancer Agency, Vancouver, BC, Canada Janssen Research & Development, San Diego, CA, USA. , Helen Diller Family Comprehensive Cancer Center, University of California San Francisco, San Francisco, CA, USA. , Janssen Research & Development, Menlo Park, CA, USA. , Department of Solid Tumor Oncology, Dana-Farber Cancer Institute and Harvard Medical School, Boston, MA, USA. , Comprehensive Cancer Centers of Nevada, Las Vegas, NV, USA. , Department of Oncology and Internal Medicine, Memorial Sloan Kettering Cancer Center and Weill Cornell Medical College, New York, NY, USA. , Groupe Uro-Genitologie, Institut Gustave Roussy, University of Paris Sud, Villejuif, France. , Department of Solid Tumor Oncology, Dana-Farber Cancer Institute and Harvard Medical School, Boston, MA, USA. , Johnson & Johnson Medical China, Shanghai, China. , Department of Medical Oncology, BC Cancer Agency, Vancouver, BC, Canada. , Department of Medical Oncology, BC Cancer Agency, Vancouver, BC, Canada. , Tom Baker Cancer Center and University of Calgary, Calgary, AB, Canada. , Department of Medical Oncology, Princess Margaret Hospital and University of Toronto, Toronto, ON, Canada. , Drug Development Unit Division of Cancer Therapeutics/Clinical Studies, The Institute for Cancer Research and Royal Marsden Hospital, Sutton, UK. , Genitourinary Oncology Service, Memorial Sloan Kettering Cancer Center and Weill Cornell Medical College, New York, NY.