Proposed prognostic scoring system evaluating risk factors for biochemical recurrence of prostate cancer after salvage radiation therapy.

OBJECTIVE - To update a previously proposed prognostic scoring system that predicts risk of biochemical recurrence (BCR) after salvage radiation therapy (SRT) for recurrent prostate cancer when using additional patients and a PSA value of 0.2 ng/ml and rising as the definition of BCR.

MATERIALS AND METHODS - We included 577 patients who received SRT for a rising PSA following radical prostatectomy in this retrospective cohort study. Clinical, pathological, and SRT characteristics were evaluated for association with BCR using relative risks (RRs) from multivariable Cox regression models.

RESULTS - With a median follow-up of 5.5 years following SRT, 354 patients (61%) experienced BCR. At 5 years following SRT, 40% of patients were free of BCR. Independent associations with BCR were identified for pre-SRT PSA (RR [doubling]: 1.25, P<0.001), pathological tumor stage (RR [T3a vs. T2]: 1.21, P=0.19; RR [T3b/T4 vs. T2]: 2.09, P<0.001; overall P<0.001), Gleason score (RR [7 vs. <7]: 1.63, P<0.001; RR [8-10 vs. <7]: 2.28, P<0.001; overall P<0.001), and surgical margin status (RR [positive vs. negative]: 0.71, P=0.003).We combined these 4 variables to create a prognostic scoring system that predicted BCR risk with a c-index of 0.66. Scores ranged from 0 to 7, and 5-year freedom from BCR for different levels of the score was as follows: Score=0-1: 66%, Score=2: 46%, Score=3: 28%, Score=4: 19%, and Score=5-7: 15%.

CONCLUSIONS - We developed a scoring system that provides an estimation of biochemical outcome after SRT. These findings will be useful for patients and physicians in decision making for radiation therapy in the salvage setting. This article is protected by copyright. All rights reserved.

BJU Int. 2015 Jul 18. doi: 10.1111/bju.13229. [Epub ahead of print]

Lee RJ1, Tzou KS1, Heckman MG2, Hobbs CJ1, Rawal B2, Diehl NN2, Peterson JL1, Paryani NN1, Ko SJ1, Daugherty LC1, Vallow LA1, Wong W3, Schild S3, Pisansky TM4, Buskirk SJ1.

1 Department of Radiation Oncology, Mayo Clinic, Jacksonville, Florida, USA.
2 Division of Biomedical Statistics and Informatics, Mayo Clinic, Jacksonville, Florida, USA.
3 Department of Radiation Oncology, Mayo Clinic, Scottsdale, Arizona, USA.
4 Department of Radiation Oncology, Mayo Clinic, Rochester, Minnesota, USA.