[Biochemical control after external radiotherapy in localized prostatic cancer: results of a modern cohort]

The present study reports biochemical outcomes of a modern series of patients with localised prostate cancer treated with external beam radiation therapy, and analyses the implications of the nadir PSA levels in monitoring outcome after treatment.

From March 1993 to March 1997, eighty three patients with clinical stages T1-T3 NxM0 prostate cancer received definitive external radiation therapy, median dose 66 Gy (range 60 to 68 Gy). Adjuvant androgen deprivation was associated in 53 high risk patients. Initial response to treatment was defined as a decrease of serum PSA to levels of < or = 1.5 ng/ml, and biochemical failure as three consecutive PSA rises over post-treatment nadir PSA value.

The 3-year actuarial BDFS was 78% +/- 7 for the whole series, 74% +/- 12 for patients treated with radiotherapy alone, and 71% +/- 10 for high risk patients treated with combination therapy (p = 0.27). Only nPSA emerged as a potential indicator of biochemical control. The probability of BDFS at 3 years was 82%, 83% and 40% for nPSA of < or = 1 ng/ml, 1-2 ng/ml and > 2 ng/ml respectively (p = 0.0409). In multivariate analysis, this correlation was independent on the effect of other variables and persisted after adjusting for the effect of hormonal therapy (p = 0.0540).

Radiation therapy is a potentially curative treatment for prostate carcinoma. Our data indicate that the nadir PSA value after radiation can be an excellent early determinant of outcome.