Prognostic value of PSA nadir < or =4 ng/mL within 4 months of high-dose radiotherapy for locally advanced prostate cancer.
OBJECTIVE
To investigate early prostate-specific antigen (PSA) kinetics after high radiation doses of 85 Gy on locally advanced prostate cancer.


METHODS
A total of 201 patients were prospectively and consecutively treated with external beam radiotherapy and a brachytherapy boost. Of the 201 patients, 104 received concomitant hormonal therapy on the decision of the referring urologist and were excluded, yielding a study population of 97 patients. The first posttreatment PSA analysis was performed not earlier than 1 month after treatment completion but within the first 4 months, and then every 4 months. Analysis of PSA kinetics included the PSA nadir (nPSA) at values of < or =4 ng/mL to < or =0.5 ng/mL. The nPSA at < or =4 ng/mL within 4 months (nPSA < or =4/4m) was the variable of interest.


RESULTS
We established highly significant associations between an nPSA of < or =1 and < or =0.5 ng/mL and the nPSA < or =4/4m (p <0.0001). A hazard ratio of 0.33 (95% Confidence Interval (CI), 0.12-0.91) underlined the lower risk of recurrence related to nPSA < or =4/4m achievement (p = 0.033). Using time-dependent covariate models for patients who did not reach an nPSA < or =4/4m, an nPSA of < or =1 ng/mL remained without prognostic significance (p = 0.06). However, for patients who reached an nPSA < or =4/4m, an nPSA of < or =1 ng/mL did significantly improve the prognosis (p <0.001), but much later after treatment. The same analysis was repeated for nPSA < or =0.5 ng/mL with similar conclusions as when nPSA < or =4/4m was obtained (p <0.01).


CONCLUSIONS
The nPSA < or =4/4m has been demonstrated to be a significant predictor of biochemical no evidence of disease after high radiation doses of 85 Gy. Its major advantage is that it was available earlier than the other nadirs.
Nickers
Philippe
P
Department of Radiation Oncology, University Hospital of Liege, Liege, Belgium. philippe.nickers@skynet.be
Albert
Adelin
A
Waltregny
David
D
Deneufbourg
Jean-Marie
JM
D000368:Aged; D000369:Aged, 80 and over; D001918:Brachytherapy; D017024:Chemotherapy, Adjuvant; D016001:Confidence Intervals; D006801:Humans; D008297:Male; D008875:Middle Aged; D009364:Neoplasm Recurrence, Local; D011379:Prognosis; D016016:Proportional Hazards Models; D011446:Prospective Studies; D017430:Prostate-Specific Antigen / Q000097:blood*; D011471:Prostatic Neoplasms / Q000097:blood* / Q000473:pathology / Q000532:radiotherapy*; D011879:Radiotherapy Dosage; D012016:Reference Values
D017430:Prostate-Specific Antigen