PSA decrease during combined-modality radiotherapy predicts for treatment outcome.
OBJECTIVE
Prostate-specific antigen (PSA) is the well-used marker in the diagnosis, prognosis, and follow-up for prostate cancer patients. Although reports have focused on the importance of pretreatment PSA levels, doubling time, and posttreatment nadirs, there is little information on the value of PSA during the course of radiotherapy.


METHODS
Retrospective review of PSA values obtained midway through a course of radiotherapy treatment for prostate cancer. Patients had a PSA (midPSA) measured after a course of external beam radiation (EBRT) before planned transperineal low-dose-rate brachytherapy implant (LDR).


RESULTS
A total of 717 patients were analyzed with a median follow-up of 5.8 years, all censored patients had a minimum follow-up of 2 years. A total of 277 patients had low-risk disease, 267 patients had intermediate risk, and 173 patients had high-risk disease. Androgen blockade was used in 512 patients. A total of 653 patients had a midPSA decrease after EBRT, the median decrease was 6.2 ng/mL. Patients who had a midPSA decrease ≥25% compared with pretreatment PSA had improved overall survival of 10.0 vs. 7.4 years (p < 0.0004) and improved disease-free survival of 9.8 vs. 7.3 years (p < 0.01). When stratified by use of androgen blockade, midPSA remained significant for both androgen and non-androgen patients.


CONCLUSIONS
PSA response after EBRT before brachytherapy predicts for long-term outcome; this may allow for risk stratification and intervention with higher LDR doses to improve outcomes.
Kubicek
Gregory J
GJ
Department of Radiation Oncology, Jefferson Medical College of Thomas Jefferson University, Philadelphia, PA, USA.
Naguib
Marco
M
Redfield
Sandy
S
Grayback
Nola
N
Olszanski
Arthur
A
Dawson
George
G
Brown
Sam I
SI
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000726:Androgen Antagonists / Q000627:therapeutic use; D005500:Follow-Up Studies; D006801:Humans; D008297:Male; D008875:Middle Aged; D011237:Predictive Value of Tests; D017430:Prostate-Specific Antigen / Q000097:blood*; D011471:Prostatic Neoplasms / Q000097:blood* / Q000188:drug therapy / Q000401:mortality / Q000532:radiotherapy*; D020266:Radiotherapy, Conformal; D050397:Radiotherapy, Intensity-Modulated; D012189:Retrospective Studies; D015996:Survival Rate; D013997:Time Factors; D016896:Treatment Outcome; D047368:Tumor Burden
D000726:Androgen Antagonists; D017430:Prostate-Specific Antigen