Isotope and patient age predict for PSA spikes after permanent prostate brachytherapy.
OBJECTIVE
To evaluate prostate-specific antigen (PSA) spikes after permanent prostate brachytherapy in low-risk patients.


METHODS
The study population consisted of 164 prostate cancer patients who were part of a prospective randomized trial comparing (103)Pd and (125)I for low-risk disease. Of the 164 patients, 61 (37.2%) received short-course androgen deprivation therapy. The median follow-up was 5.4 years. On average, 11.1 post-treatment PSA measurements were obtained per patient. Biochemical disease-free survival was defined as a PSA level of < or =0.40 ng/mL after nadir. A PSA spike was defined as an increase of > or =0.2 ng/mL, followed by a durable decline to prespike levels. Multiple parameters were evaluated as predictors for a PSA spike.


RESULTS
Of the 164 patients, 44 (26.9%) developed a PSA spike. Of the 46 hormone-naive (125)I patients and 57 hormone-naive (103)Pd patients, 21 (45.7%) and 8 (14.0%) developed a PSA spike. In the hormone-naive patients, the mean time between implantation and the spike was 22.6 months and 18.7 months for (125)I and (103)Pd, respectively. In patients receiving neoadjuvant androgen deprivation therapy, the incidence of spikes was comparable between isotopes ((125)I 28.1% and (103)Pd 20.7%). The incidence of spikes was substantially different in patients <65 years vs. > or =65 years old (38.5% vs. 16.3%). On multivariate Cox regression analysis, patient age (p < 0.001) and isotope (p = 0.002) were significant predictors for spike.


CONCLUSIONS
In low-risk prostate cancer, PSA spikes are most common in patients implanted with (125)I and/or <65 years of age. Differences in isotope-related spikes are most pronounced in hormone-naive patients.
Bostancic
Chelsea
C
Schiffler Cancer Center, Wheeling Jesuit University, Wheeling, WV 26003-6300, USA.
Merrick
Gregory S
GS
Butler
Wayne M
WM
Wallner
Kent E
KE
Allen
Zachariah
Z
Galbreath
Robert
R
Lief
Jonathan
J
Gutman
Sarah E
SE
D000367:Age Factors; D000368:Aged; D000704:Analysis of Variance; D000726:Androgen Antagonists / Q000627:therapeutic use; D001918:Brachytherapy; D018572:Disease-Free Survival; D006801:Humans; D007457:Iodine Radioisotopes / Q000627:therapeutic use; D008297:Male; D008875:Middle Aged; D010165:Palladium / Q000627:therapeutic use; D011446:Prospective Studies; D017430:Prostate-Specific Antigen / Q000097:blood*; D011471:Prostatic Neoplasms / Q000097:blood* / Q000532:radiotherapy*; D011868:Radioisotopes / Q000627:therapeutic use
D000726:Androgen Antagonists; D007457:Iodine Radioisotopes; D011868:Radioisotopes; D010165:Palladium; D017430:Prostate-Specific Antigen