Radiation rescue for biochemical failure after surgery for prostate cancer: predictive parameters and an assessment of contemporary predictive models.
OBJECTIVE
To determine pretreatment prognostic variables that predict outcome of radiotherapy for biochemical failure after prostate cancer surgery and evaluate contemporary clinical decision tools for patient selection.


METHODS
Fifty patients were identified with failure after rescue radiation was defined as a confirmed rise in PSA, distant metastases, prostate cancer death, or initiation of hormonal therapy. Univariate analysis and multivariate Cox models were constructed. Outcome was compared with decision tree and recursive partitioning predictive models.


RESULTS
The median preradiation PSA (pre-RT PSA) was 1.2 ng/mL and the median dose of radiation was 66.6 Gy; median follow-up was 39.6 months. Overall, the estimated 3-year failure free survival was 54%, 95%CI [43,74]. Seminal vesicle involvement (SVI) (P = 0.003) and preradiation PSA Doubling Time (PSADT) <10 months (P = 0.01) were both significant predictors for treatment failure whereas pre-RT PSA was of borderline significance (P = 0.07). On multivariate analysis a pre-RT PSA of >1 and SVI were associated with hazard ratios of 6.2 and 7.3 (P = 0.01 and P = 0.004), respectively. An additional Cox model constructed for 31 patients for whom pre-RT PSADT could be calculated showed PSADT and SVI to be independent prognostic parameters. Two predictive models, a decision tree analysis, and a recursive partitioning model were moderately accurate in predicting outcome in this series, however, high-risk patients experienced less treatment failures than predicted.


CONCLUSIONS
Pre-RT PSA <1 ng/mL, longer PSADT (>10 months) and no SVI are associated with improved outcome after rescue radiation. Contemporary clinical prediction tools are imperfect predictors of outcome for rescue radiation therapy.
Symon
Zvi
Z
Oncology Institute, Chaim Sheba Medical Center, Tel Hashomer, Israel. symonz@sheba.health.gov.il
Kundel
Yulia
Y
Sadetzki
Siegal
S
Oberman
Bernice
B
Ramon
Jacob
J
Laufer
Menachem
M
Catane
Raphael
R
Pfeffer
M Raphael
MR
D003663:Decision Trees; D006801:Humans; D008297:Male; D018579:Patient Selection; D011379:Prognosis; D016016:Proportional Hazards Models; D017430:Prostate-Specific Antigen / Q000097:blood; D011468:Prostatectomy; D011471:Prostatic Neoplasms / Q000097:blood / Q000532:radiotherapy* / Q000601:surgery*; D011879:Radiotherapy Dosage; D011881:Radiotherapy, Computer-Assisted; D016879:Salvage Therapy; D016019:Survival Analysis; D017211:Treatment Failure
D017430:Prostate-Specific Antigen