Real-world Outcomes and Factors Predicting Survival and Completion of Radium 223 in Metastatic Castrate-resistant Prostate Cancer

Abstract

Aims: To analyse outcomes in metastatic castrate-resistant prostate cancer (mCRPC) patients treated with radium 223 (Ra-223) across the Yorkshire and Humber Cancer Network.

Materials and methods: A regional, multicentre, retrospective cohort study of 189 men undergoing Ra-223 for mCRPC between March 2014 and April 2017 was undertaken. Factors predicting overall survival and completion of planned treatment were assessed.

Results: The median overall survival for the entire cohort was 10.5 months. Those completing five to six cycles of Ra-223 had a higher overall survival of 18.6 months. On multivariable analysis, four factors remained independent significant predictors of overall survival: age (P = 0.005, hazard ratio 1.07 [1.02-1.12]); number of cycles of Ra-223: 5-6 versus 1-4 (P ≤ 0.001, hazard ratio 0.10 [0.005-0.20]); baseline alkaline phosphatase (P = 0.044, hazard ratio 1.06 [1.002-1.12]); neutrophil-to-lymphocyte ratio (P = 0.033, hazard ratio 1.19 [1.01-1.40]). Baseline performance status 0 versus 2 (P = 0.026, odds ratio 0.080 [0.001-0.74]) and higher baseline haemoglobin (P = 0.028, odds ratio 1.04 [1.004-1.074]) were independent predictors of the completion of five to six cycles of Ra-223.

Conclusions: Younger age, completion of five to six cycles of Ra-223, lower alkaline phosphatase and neutrophil-to-lymphocyte ratio are predictors of overall survival. This is the first study to report neutrophil-to-lymphocyte ratio as an independent predictor of overall survival in a Ra-223 cohort. Good performance status and higher baseline haemoglobin predict the completion of five to six cycles of Ra-223.

Keywords: Metastatic castrate-resistant prostate cancer; neutrophil-to-lymphocyte ratio; overall survival; radium 223.