Adjuvant versus salvage radiation therapy for prostate cancer patients with adverse pathologic features: comparative analysis of long-term outcomes.
OBJECTIVE
To compare long-term outcomes of men with adverse pathologic features after adjuvant radiation therapy (ART) versus salvage radiation therapy (SRT) after radical prostatectomy at our institution.


METHODS
Patients treated with postprostatectomy radiation therapy with pT3 tumors, or pT2 with positive surgical margins, were identified. Cumulative freedom from biochemical failure (FFBF), freedom from metastatic failure (FFMF), and overall survival rates were estimated utilizing the Kaplan-Meier method. Multivariate analyses were performed to determine independent prognostic factors correlated with study endpoints. Propensity score analyses were performed to adjust for confounding because of nonrandom treatment allocation.


RESULTS
A total of 186 patients with adverse pathologic features treated with ART or SRT were identified. The median follow-up time after radical prostatectomy was 103 and 88 months after completion of radiation therapy. The Kaplan-Meier estimates for 10-year FFBF was 73% and 41% after ART and SRT, respectively (log-rank, P=0.0001). Ten-year FFMF was higher for patients who received ART versus SRT (98.6% vs. 80.9%, P=0.0028). On multivariate analyses there was no significant difference with respect to treatment group in terms of FFBF, FFMF, and overall survival after adjusting for propensity score.


CONCLUSIONS
Although unadjusted analyses showed improved FFBF with ART, the propensity score-adjusted analyses demonstrated that long-term outcomes of patients treated with ART and SRT do not differ significantly. These results, with decreased effect size of ART after adjusting for propensity score, demonstrate the potential impact of confounding on observational research.
*Department of Radiation Oncology †Robert Wood Johnson School of Osteopathic Medicine, University of Medicine & Dentistry of New Jersey, New Brunswick, NJ ‡Department of Pharmacology and Experimental Therapeutics, Division of Biostatistics §Department of Urology, Kimmel Cancer Center, Jefferson Medical College, Thomas Jefferson University, Philadelphia, PA.
Mark V
MV
Mishra
Eli D
ED
Scher
Jocelyn
J
Andrel
Andrew C
AC
Margules
Sarah E
SE
Hegarty
Edouard J
EJ
Trabulsi
Terry
T
Hyslop
Robert B
RB
Den
Costas D
CD
Lallas
Leonard G
LG
Gomella
Adam P
AP
Dicker
Timothy N
TN
Showalter
D000328:Adult; D000368:Aged; D018572:Disease-Free Survival; D006801:Humans; D008297:Male; D008875:Middle Aged; D015999:Multivariate Analysis; D009364:Neoplasm Recurrence, Local / Q000473:pathology*; D018365:Neoplasm, Residual / Q000473:pathology / Q000532:radiotherapy*; D016016:Proportional Hazards Models; D011468:Prostatectomy; D011471:Prostatic Neoplasms / Q000473:pathology / Q000532:radiotherapy*; D018714:Radiotherapy, Adjuvant / Q000379:methods; D016879:Salvage Therapy / Q000379:methods*