Prostate-specific antigen kinetics following external-beam radiotherapy and temporary (Ir-192) or permanent (I-125) brachytherapy for prostate cancer.
OBJECTIVE
The aim of the study was the evaluation of PSA kinetics after different radiotherapy methods.


METHODS
Two-hundred and ninety five patients received external-beam radiotherapy (EBRT; 70.2 Gy; n=135), Ir-192 brachytherapy as a boost to EBRT (HDR-BT; 18 Gy+50.4 Gy; n=66) or I-125 brachytherapy (LDR-BT; 145 Gy; n=94) as monotherapy. "PSA bounce" was defined as a PSA rise of > or = 0.2 ng/ml followed by spontaneous return to prebounce level or lower, biochemical failure as "nadir+2 ng/ml".


RESULTS
Patients without biochemical failure reached a lower nadir after brachytherapy (median < or = 0.05 ng/ml after LDR- and HDR-BT without NHT) in comparison to EBRT (0.55 ng/ml without NHT; p<0.01). Not a single patient without NHT and a nadir <0.1 ng/ml failed biochemically (0% vs. 45% with a nadir > or = 0.1 ng/ml; p<0.01). PSA bounces were found predominantly in the LDR-BT group (42% vs. 23%/20% after HDR-BT/EBRT; p<0.01). In a multivariate Cox regression analysis, LDR-BT and HDR-BT were associated with a significantly lower biochemical failure rate in comparison to EBRT.


CONCLUSIONS
PSA kinetics differ significantly following different radiotherapy methods. A lower nadir and a higher biochemical control rate suggest a higher radiobiological efficiency of brachytherapy in comparison to EBRT (with a dose of 70.2 Gy).
Pinkawa
Michael
M
Department of Radiation Oncology, RWTH Aachen University, Aachen, Germany. MPinkawa@ukaachen.de
Piroth
Marc D
MD
Holy
Richard
R
Fischedick
Karin
K
Schaar
Sandra
S
Borchers
Holger
H
Heidenreich
Axel
A
Eble
Michael J
MJ
D000230:Adenocarcinoma / Q000097:blood / Q000401:mortality / Q000473:pathology / Q000532:radiotherapy*; D000368:Aged; D000369:Aged, 80 and over; D001918:Brachytherapy / Q000379:methods*; D016009:Chi-Square Distribution; D015331:Cohort Studies; D016001:Confidence Intervals; D004307:Dose-Response Relationship, Radiation; D005500:Follow-Up Studies; D006801:Humans; D053208:Kaplan-Meier Estimate; D008297:Male; D008875:Middle Aged; D009367:Neoplasm Staging; D016016:Proportional Hazards Models; D017430:Prostate-Specific Antigen / Q000493:pharmacokinetics* / Q000528:radiation effects; D011471:Prostatic Neoplasms / Q000097:blood / Q000401:mortality / Q000473:pathology / Q000532:radiotherapy*; D011879:Radiotherapy Dosage; D011882:Radiotherapy, High-Energy / Q000379:methods*; D018570:Risk Assessment; D015996:Survival Rate; D013997:Time Factors; D016896:Treatment Outcome
D017430:Prostate-Specific Antigen