Prostate-specific antigen: effect of pelvic irradiation.
OBJECTIVE
To study the effect of pelvic irradiation on the level of serum prostate-specific antigen (PSA).


METHODS
Of 33 patients treated with pelvic irradiation to the prostate and seminal vesicles for anal and rectal cancer, 26 received 50.4 Gy or more (1. 8 Gy per fraction), and seven received 25.0 Gy (5.0 Gy per fraction). PSA levels were measured before (n = 33), during (n = 26), and after radiation therapy (n = 33). In 24 patients, follow-up (mean, 15.7 months) PSA data were obtained. Actual and pretreatment PSA levels were compared (Wilcoxon rank test).


RESULTS
During the first 3 weeks in all patients, PSA levels rose steeply, culminating in a 3. 7-fold increase (P =.02). At the end of radiation therapy (7 weeks), the PSA level was no longer significantly different from the pretreatment value. In the long term, the PSA level decreased to 77% of the pretreatment value (P =.04).


CONCLUSIONS
Irradiation of the prostate initially elevates serum PSA levels. Apparently PSA release is determined by the duration of radiation therapy, while the accumulated dose has a minor effect. In the long term, PSA production is impaired after radical radiation therapy. PSA reference concentrations should be adjusted to these reduced levels.
Gripp
S
S
Department of Radiation Oncology, Klinik für Strahlentherapie und Radiogische Onkologie, Heinrich-Heine-Universität, Düsseldorf, Germany. stephan.gripp@uni-duesseldorf.de
Haller
J C
JC
Metz
J
J
Willers
R
R
D001005:Anus Neoplasms / Q000097:blood / Q000532:radiotherapy; D003131:Combined Modality Therapy; D005500:Follow-Up Studies; D006801:Humans; D008297:Male; D010388:Pelvis / Q000528:radiation effects*; D017430:Prostate-Specific Antigen / Q000097:blood / Q000528:radiation effects*; D011879:Radiotherapy Dosage; D012004:Rectal Neoplasms / Q000097:blood / Q000532:radiotherapy; D018709:Statistics, Nonparametric; D013997:Time Factors
D017430:Prostate-Specific Antigen