Effect of PSA nadir and the time to nadir in the disease-free period in localized prostatic carcinoma treated with radical radiation

OBJECTIVE
To evaluate the prognostic significance of PSA nadir (nPSA) and the time to nadir in disease free of recurrence (DFR) in localized carcinoma of prostate treated with radical radiotherapy (RTR).

MATERIAL AND METHODS
From October 1984 to December 1998, 86 patients have been treated with prostate carcinoma. It was considered of Low risk those patients with PSA < or = 10 ng/ml, Gleason = 6 or stage T1-T2. Moderate risk: those with one elevated of the three parameters. High risk: two or more parameters. The treatment was carried out in a lineal accelerator using photons of 15 MV, with standard technique and frationation, administering a median dose of 66 Gy (58-75 Gy). It was defined disease free of recurrence (DFR), the time to clinical PSA or biochemical failure. This one was defined as the time starting from the date of nadir PSA to the second consecutive increase of PSA value after three separate serial measurements separated for at least one month.

RESULTS
The median of initial PSA value was of 16 ng/ml (1-270), initial clinical stage T1-T2 (70p), stages T3-T4 (14p), and unknown in 2p. The median of Gleason score was 6 (2-10). According to the group of risk they were classified as: low risk in 16 patients (19%), moderated risk in 22 patients (26%), high risk in 21 patients (24%), and unknown in 27 patients (31%). Median nPSA value was 0.8 ng/ml (limits: 0-139) and the median time elapsed between the initial PSA and nPSA has been of 11 months (limits: 0-72 months). The actuarial DFR projected to five years in those patients with nPSA = 1 ng/ml was of 67% vs. 47% in patient with nPSA figures > 1 ng/ml (p = 0.0018). The PFD in patients with time to nadir (t nadir) < 12 months it was of 20% vs. 80% in patients with t nadir > 12 months (p < 0.0001). Multivariate analysis demonstrated that time to nadir (H.R: 0.11 p = 0.001), group of risk (H.R: 28.72 p = 0.020), and grade of differentiation (HR: 28.72 p = 0.010), were determinant to DFR.

CONCLUSIONS
nPSA is an important factor to determine the objective response to radiotherapy. nPSA and time to nadir are prognostic factors that influences significantly on the DFR. The indication of adjuvant treatment in those patients with unfavorable prognostic factors such us those who do not reach nadir PSA < or = 1 ng/ml and time to nadir < or = 12 months, deserves the realization of a prospective study.

CITA DEL ARTÍCULO Rev Med Univ Navarra. 2001 Jan-Mar;45(1):20-8