Abstract
Purpose: To explore the association between progression-free survival and overall survival time in patients with castration-resistant prostate cancer treated with microtubule-targeted therapies.
Experimental Design: We retrospectively studied patients treated in three trials evaluating a taxane or an epothilone for progressive castration-resistant prostate cancer. Study subjects were 98 patients with bone metastases; 63 of them also had soft tissue lesions. All scans were reviewed independently. Associations of radiographic progression-free survival and prostate-specific antigen (PSA) progression-free survival with survival time were measured using Kendall's τ, adjusted for right censoring. A smoothing procedure was applied to estimate Kendall's τ within each neighborhood of the follow-up process.
Results: The overall associations between progression-free survival time and overall survival time were moderate: 0.4 for radiographic progression-free survival and 0.33 for PSA progression-free survival. The association between radiographic progression-free survival and overall survival was weakest early in the follow-up process, whereas the PSA association was weakest when the progression-free survival–related event (PSA progression, death, or censoring) occurred after 6 months from the start of treatment.
Conclusions: Current measures of progression-free survival time for men with castration-resistant prostate cancer are not strongly concordant with survival time. Factors that attenuate the association include interval censoring and the discontinuation of therapy early in the follow-up due to imaging changes that may not reflect true failure of the treatment. For radiographic progression-free survival, the association may be increased by requiring confirmation of progression with a second scan, as is routinely done when assessing response.
- response
- progression
- prognosis
- outcome measures
- prostate cancer
- hormone-refractory
Footnotes
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Grant support: Memorial Sloan-Kettering Cancer Center Specialized Programs of Research Excellence in Prostate Cancer, CA-05826, and the Prostate Cancer Foundation.
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The costs of publication of this article were defrayed in part by the payment of page charges. This article must therefore be hereby marked advertisement in accordance with 18 U.S.C. Section 1734 solely to indicate this fact.
- Accepted December 8, 2006.
- Received July 31, 2006.
- Revision received October 24, 2006.
Volume 13, Issue 5
