Chicago—Clinical outcomes of men with metastatic castration-resistant prostate cancer (mCRPC) treated with enzalutamide (XTANDI) after chemotherapy correlate with health-related quality of life (HRQoL) both at treatment initiation and its change longitudinally, researchers reported at the American Society of Clinical Oncology annual meeting in Chicago.
The findings were derived from post-hoc analyses of data collected prospectively during the phase III AFFIRM study in which 1,199 men with mCRPC who had failed docetaxel (Taxotere) were randomized 2:1 to treatment with enzalutamide, 160 mg/day, or placebo. HRQoL was assessed during the trial using the validated Functional Assessment of Cancer Therapy-Prostate (FACT-P) questionnaire, which was completed before randomization, at week 13, and every 12 weeks thereafter while on study treatment.
Correlations between FACT-P scores were explored with both overall survival and radiographic progression-free survival (rPFS). The results showed that for both clinical outcomes, the prognosis was better for men with better HRQoL at baseline and also if their HRQoL improved during treatment with enzalutamide.
“In the future, the findings from these analyses represent additional information that might be included for shared decision-making about initiating enzalutamide after chemotherapy for men with mCRPC failing chemotherapy and also for deciding whether or not to continue enzalutamide treatment,” said first author Kurt Miller, MD, PhD, speaking to Urology Times on behalf of the AFFIRM investigators.
“However, more studies are needed to validate these observations and to demonstrate that therapy selection based on quality of life helps patients,” added Dr. Miller, chair of urology at Charité Universitätsmedizin, Berlin.
The prognostic value of baseline and time-dependent HRQoL scores was investigated using a multivariate Cox regression model that adjusted for treatment and relevant clinical and demographic variables. Separate analyses were performed using the total FACT-P score and for scores in the subdomains of physical well-being, functional well-being, and “additional concerns” (subscale consisting of items relating to prostate cancer and its treatment).
FACT-P scores correlate with rPFS
Results of univariate analyses showed that better HRQoL at baseline for the total and each of the three subdomain scores was associated with significantly reduced risks of death and of radiographic progression. In the multivariate model examining baseline scores and clinical outcomes, total FACT-P and functional well-being scores remained independent predictors of overall survival, and the total FACT-P score was also a prognostic factor for rPFS. Specifically, each 10-point improvement in FACT-P total score, which is considered to represent a quality of life response to treatment, corresponded to a 12% decrease in risk of death and a 5% decrease in risk of radiographic progression.
Longitudinal changes in FACT-P total score and the physical well-being score were significantly associated with rPFS, and all of the quality of life variables assessed correlated with overall survival.
Dr. Miller acknowledged there is no simple explanation to account for the associations found between HRQoL and patient outcomes considering that quality of life is a multidimensional issue. However, findings from the analyses suggest that functional and physical status, both of which are measured by performance status scores, are important components as they may reflect the individual’s physical state that would in turn correlate with his survival.
Dr. Miller receives consulting and lecture fees from Astellas Pharma. Several of his co-authors have a financial or other relationship with Astellas and/or other pharmaceutical companies.
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