'Very Early' Salvage Radiotherapy Improves Distant Metastasis-Free Survival

'Early' salvage radiotherapy (SRT) following radical prostatectomy (RP) for prostate cancer is commonly advocated in place of adjuvant radiotherapy. Herein, we aimed to determine the optimal definition of 'early' SRT.

A multi-institutional retrospective study of 657 men who underwent SRT between 1986-2013. Two comparisons were used to determine the optimal definition of early SRT; 1) Time from RP to SRT (<9, 9-21, 22-47, and >48 months), and 2) level of detectable pre-SRT PSA (0.01-0.2, >0.2-0.5, >0.5 ng/mL). Outcomes included biochemical relapse-free survival (bRFS), freedom from salvage-androgen deprivation therapy (FF-SADT), distant metastases-free survival (DMFS), and prostate cancer-specific survival (PCSS).

The median follow-up was 9.8 years. The time from RP to SRT did not correlate with 10-year bRFS rates (R(2) 0.18). Increasing pre-SRT PSA had a strong correlation with bRFS (R(2) 0.91). Increasing detectable pre-SRT PSA (0.01-0.2, 0.2-0.5, >0.5 ng/mL) predicted for worse 10-year bRFS (62%, 44%, and 27%, p<0.001), FF-SADT (77%, 66%, and 49%, p<0.001), DMFS (86%, 79%, and 66%, p<0.001) and PCSS (93%, 89%, and 80%, p=0.001). On multivariable analysis, 'early' SRT (PSA >0.2-0.5 ng/mL) was associated with a 2-fold increase in biochemical failure, use of salvage ADT, and distant metastases compared to 'very early' SRT (0.01-0.2 ng/mL).

The duration from RP to SRT is not independently prognostic for outcomes post-SRT and should not be used to define early SRT. Grouping all patients with pre-SRT PSAs of ≤0.5 ng/mL may be inadequate to define 'early' SRT, and has relevant impact on ongoing and future clinical trials.

The Journal of urology. 2016 Sep 07 [Epub ahead of print]

Ahmed Abugharib, William C Jackson, Vasu Tumati, Robert T Dess, Jae Y Lee, Shuang G Zhao, Moaaz Soliman, Zachary S Zumsteg, Rohit Mehra, Felix Y Feng, Todd M Morgan, Neil Desai, Daniel E Spratt

University of Michigan Department of Radiation Oncology., University of Texas Southwestern, Department of Radiation Oncology., Cedars Sinai, Department of Radiation Oncology., University of Michigan Department of Pathology., University of Michigan Department of Radiation Oncology; University of California San Francisco, Department of Radiation Oncology., University of Michigan Department of Urology., University of Texas Southwestern, Department of Radiation Oncology. Electronic address: .

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