PSA kinetics and PSA bounce following permanent seed prostate brachytherapy.
OBJECTIVE
To report the incidence, timing, and magnitude of the benign prostate-specific antigen (PSA) bounce after 125I prostate brachytherapy and correlate the bounce with clinical and/or dosimetric factors.


METHODS
From March 1999 to August 2003, a total of 292 men received 125I prostate brachytherapy without androgen deprivation or supplemental beam radiotherapy and have PSA follow-up >30 months. Implants were preplanned using transrectal ultrasound (TRUS) and performed under transrectal ultrasound/fluoroscopy guidance using preloaded needles. A PSA bounce is defined as an increase >or=0.2 ng/ml with spontaneous return to prebounce level or lower.


RESULTS
Resolved PSA bounces were seen in 40% of men with follow-up >30 months. Median onset was 15 months, and median magnitude was 0.76 ng/ml. Magnitude >2 ng/ml was seen in 15%. The only clinical or dosimetric factor predictive of bounce in multivariate analysis was younger age. Median time to increasing PSA level indicative of failure was 30 months.


CONCLUSIONS
Benign PSA bounces are common after 125I prostate brachytherapy, especially in younger men. An increase >2 ng/ml above the nadir was seen in 15%. Magnitude of increase does not distinguish bounce from failure. Time to the start of the PSA increase can be helpful, but is not absolute. The PSA bounce does not predict subsequent failure. Caution is advised in interpreting an early increasing PSA level in the first 30 months after 125I brachytherapy in favorable-risk patients.
Crook
Juanita
J
Department of Radiation Oncology, University Health Network, Princess Margaret Hospital, Toronto, Ontario, Canada. juanita.crook@rmp.uhn.on.ca
Gillan
Caitlin
C
Yeung
Ivan
I
Austen
Lynette
L
McLean
Michael
M
Lockwood
Gina
G
D000367:Age Factors; D000368:Aged; D000369:Aged, 80 and over; D001918:Brachytherapy / Q000379:methods*; D005500:Follow-Up Studies; D006801:Humans; D007457:Iodine Radioisotopes / Q000627:therapeutic use; D008297:Male; D008875:Middle Aged; D015999:Multivariate Analysis; D017430:Prostate-Specific Antigen / Q000097:blood*; D011471:Prostatic Neoplasms / Q000097:blood* / Q000532:radiotherapy*; D013997:Time Factors
D007457:Iodine Radioisotopes; D017430:Prostate-Specific Antigen