Metastasis-free survival (MFS) is a valid surrogate endpoint for overall survival (OS) among some patients with localized prostate cancer, according to an article published in the Journal of Clinical Oncology.1
OS data from prostate cancer clinical trials in the adjuvant setting can take over a decade to mature, creating a need for reliable surrogate markers. For this review of completed and ongoing randomized clinical trials, researchers evaluated data from patients with prostate cancer to determine whether MFS or disease-free survival (DFS) are valid surrogate markers for OS.
Twenty four trials had DFS data for 21,140 patients; 19 trials had MFS data for 12,712 patients.
Among patients with DFS data, 61% were enrolled in radiation trials and 63% had high-risk disease. Among patients with MFS data, 90% were in enrolled in radiation trials and 66% had high-risk disease.
Five-year OS was 84% for the entire cohort, where the estimated chance of prostate cancer–specific mortality over 10 years was about 15%; 5-year DFS and MFS rates were 76% and 79%, respectively. The DFS correlation with OS was .85; the MFS correlation with OS was .91.
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The authors noted a “strong correlation between log(HR [hazard ratio])-OS and log(HR)-MFS across trials (R2, 0.92 [95% CI, 0.81 to 0.95]), and the high correlation remained when nonprostate cancer deaths were censored (R2, 0.89 [95% CI, 0.72 to 0.93].”
They concluded that MFS is a “strong” surrogate for OS in this patient population.
- Xie W, Regan MM, Buyse M, et al. Metastasis-free survival is a strong surrogate of overall survival in localized prostate cancer. J Clin Oncol. 2017 Aug 10. doi: 10.1200/JCO.2017.73.9987 [Epub ahead of print]