Purpose: Pain from castration-refractory prostate cancer (CRPC) bone metastases is a common event. Although it is assumed that pain represents an adverse prognostic factor, this variable has not been extensively evaluated. The objective of this study was to determine whether men with CRPC who had higher pain interference scores at baseline had worse clinical outcomes compared with men who had lower pain scores.
Patients and methods: Data from three randomized phase III multicenter trials conducted by the Cancer and Leukemia Group B from 1992 to 1998 were combined. Eligible patients had progressive CRPC adenocarcinoma of the prostate, an Eastern Cooperative Oncology Group performance status of 0 to 2, and adequate hematologic, renal, and hepatic functions. Seven items from the Brief Pain Inventory were used to assess the impact of pain on a range of daily activities and quality of life, each rated on a scale from 0 to 10.
Results: In 599 men, the median pain interference scores was 17 (interquartile range, 4 to 34), and 38% of the men had opioid analgesic use at baseline. There was a statistically significant association between pain interference scores and risk of death. The median survival times were 17.6 months (95% CI, 16.1 to 19.1 months) and 10.2 months (95% CI, 8.6 to 11.3 months; P < .001) in men with low (< 17) and high (>or= 17) pain scores, respectively. Pain was inversely associated with likelihood of prostate-specific antigen decline, objective response, and time to bone progression.
Conclusion: This analysis demonstrates that pain is a statistically significant predictor of overall survival in men with metastatic CRPC. These results need to be validated prospectively in future phase III trials.