[Nadir PSA and kinetics of PSA decline between the 3rd and 6th month after external beam radiotherapy for T1 T2 Nx M0 localized prostate cancer: value of the prediction of the risk of biological progression].
BACKGROUND
This study analyses the results of external beam radiotherapy in stage T1 T2 Nx M0 prostate cancer, with reference to the nadir PSA and the kinetics of PSA decline.


METHODS
65 patients with T1 T2 Nx M0 localized prostate cancer were treated by external beam radiotherapy (conventional or conformal) between 1990 and 1999. Two populations of 22 and 25 patients were distinguished according to the nadir PSA: population A with a nadir < or = 0.5 ng/ml or not yet reached, but with PSA < or = 0.5 ng/ml and population B with a nadir > 0.5 ng/ml. The various clinical and laboratory parameters and the kinetics of PSA decline (calculation based on the course of PSA between the first 3 and 6 months after irradiation) were compared by statistical tests (Chi-square, Student t test). According to the ASTRO criteria, the results in terms of absence of biochemical progression were evaluated by non-parametric Kaplan-Meier estimate.


RESULTS
No biochemical progression was observed in population A with a mean follow-up of 29.5 months. The absence of biochemical progression in population B at 42 months was 52.77%. The baseline PSA (p = 0.009), the dose delivered (p = 0.027), and the kinetics of PSA decline (p = 0.0069) were identified as predictive factors. The patient with a zero kinetic developed biochemical progression, while 91.3% of patients with a kinetic < 0.35 ng/ml/month remained free of biochemical progression. A group of patients (median nadir: 0.8 ng/ml, baseline PSA < 10 ng/ml and kinetic < 0.35 ng/ml/month) was distinguished by its good prognosis.


CONCLUSIONS
In stage T1-T2 prostate cancer, the value of the nadir PSA is an essential prognostic factor. The kinetics of PSA decline appear to have an early predictive role.
Almeras
Christophe
C
Clinique Urologique, Hôpital Cochin, Paris, France.
Zerbib
Marc
M
Eschwege
François
F
Debré
Bernard
B
D000368:Aged; D014408:Biomarkers, Tumor / Q000097:blood; D018450:Disease Progression; D005500:Follow-Up Studies; D006801:Humans; D008297:Male; D009367:Neoplasm Staging; D011237:Predictive Value of Tests; D011379:Prognosis; D017430:Prostate-Specific Antigen / Q000097:blood*; D011471:Prostatic Neoplasms / Q000097:blood / Q000175:diagnosis / Q000532:radiotherapy*; D020266:Radiotherapy, Conformal; D012189:Retrospective Studies; D013997:Time Factors
D014408:Biomarkers, Tumor; D017430:Prostate-Specific Antigen