Comparison of biochemical failure definitions for permanent prostate brachytherapy.
OBJECTIVE
To assess prostate-specific antigen (PSA) failure definitions for patients with Stage T1-T2 prostate cancer treated by permanent prostate brachytherapy.


METHODS
A total of 2,693 patients treated with radioisotopic implant as solitary treatment for T1-T2 prostatic adenocarcinoma were studied. All patients had a pretreatment PSA, were treated at least 5 years before analysis, 1988 to 1998, and did not receive hormonal therapy before recurrence. Multiple PSA failure definitions were tested for their ability to predict clinical failure.


RESULTS
Definitions which determined failure by a certain increment of PSA rise above the lowest PSA level to date (nadir + x ng/mL) were more sensitive and specific than failure definitions based on PSA doubling time or a certain number of PSA rises. The sensitivity and specificity for the nadir + 2 definition were 72% and 83%, vs. 51% and 81% for 3 PSA rises. The surgical type definitions (PSA exceeding an absolute value) could match this sensitivity and specificity but only when failure was defined as exceeding a PSA level in the 1-3 ng/mL range and only when patients were allowed adequate time to nadir. When failure definitions were compared by time varying covariate regression analysis, nadir + 2 ng/mL retained the best fit.


CONCLUSIONS
For patients treated by permanent radioisotopic implant for prostate cancer, the definition nadir + 2 ng/mL provides the best surrogate for failure throughout the entire follow-up period, similar to patients treated by external beam radiotherapy. Therefore, the same PSA failure definition could be used for both modalities. For brachytherapy patients with long-term follow-up, at least 6 years, defining failure as exceeding an absolute PSA level in the 0.5 ng/mL range may be reasonable.
Kuban
Deborah A
DA
Department of Radiation Oncology, The University of Texas M. D. Anderson Cancer Center, Houston, TX 77030, USA. dakuban@mdanderson.org
Levy
Larry B
LB
Potters
Louis
L
Beyer
David C
DC
Blasko
John C
JC
Moran
Brian J
BJ
Ciezki
Jay P
JP
Zietman
Anthony L
AL
Zelefsky
Michael J
MJ
Pisansky
Thomas M
TM
Elshaikh
Mohamed
M
Horwitz
Eric M
EM
D000230:Adenocarcinoma / Q000097:blood* / Q000532:radiotherapy*; D001918:Brachytherapy / Q000379:methods*; D005500:Follow-Up Studies; D006801:Humans; D008297:Male; D017430:Prostate-Specific Antigen / Q000097:blood*; D011471:Prostatic Neoplasms / Q000097:blood* / Q000532:radiotherapy*; D012044:Regression Analysis; D012680:Sensitivity and Specificity; D017211:Treatment Failure
D017430:Prostate-Specific Antigen