[Incidence and prognostic factors for biochemical recurrence after radical radiotherapy]

The aim of this study is to analyze the outcomes obtained after External-Beam Radiotherapy (3D EBRT)in patients with prostate cancer.

The study includes 503 patients (p) treated at the Hospital General Universitario Gregorio Marañón in Madrid, diagnosed between 2000-2007, with low, intermediate or high risk prostate cancer (D'Amico risk groups), treated with 3D EBRT. Biochemical recurrence (BR) was defined as nadir +2 following Phoenix's criterion. The median follow-up was 59 months (range 3.4-104.2).

Biochemical relapse-free survival (bRFS) rates at 5 and 8 years were 88 ± 2% and 76 ± 3%, respectively. Multivariate analysis indicated initial PSA (p <0.02), perineural invasion in biopsy specimen (p <0.00), EBRT dose (p = 0.01) and the use of androgen deprivation therapy (ADT)(p = 0.00) to be independent predictors of relapse. Nadir PSA value <0.3 ng/ml was associated with the best 5-year bRFS (96.6% versus 56.5% if nadir PSA > 1.3 ng/ml). Late urinary and rectal toxicity ≥ 3 was lower than 5%. Active rescue treatment was indicated in 85% of patients. Only 10 patients died of prostate cancer.

The biochemical failure rate is determined by classical pretreatment features (initial PSA level, risk group, perineural invasion) and low- dose EBRT (≤ 72 Gy), nadir PSA value and the use of ADT in intermediate and high risk groups.