Prostate Cancer: Metastasis-free Survival Is A Surrogate for OS

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.

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.

Reference

1. 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]