UROLOGICAL ONCOLOGY

Radiotherapy for men with isolated increase in serum prostate specific antigen after radical prostatectomy
Macdonald OK, Schild SE, Vora SA, Andrews PE, Ferrigni RG, Novicki DE, Swanson SK, Wong WW
Department of Radiation Oncology, Section of Urology, Mayo Clinic Scottsdale, 13400 E. Shea Boulevard, Scottsdale, AZ, 85259, USA
J Urol. 2003; 170: 1833-7

• Purpose: In this retrospective study we determined the results of salvage external beam radiation therapy (RT) to the prostate bed for isolated increase of serum prostate specific antigen (PSA) after radical prostatectomy.
• Materials and Methods: A total of 60 patients underwent RT for PSA failure after radical prostatectomy from 1993 to 1999. Median followup was 51 months. Biochemical disease-free survival (bDFS) with a serum PSA of 0.3 ng/mL or less was estimated using the Kaplan-Meier method. Potential prognostic factors were evaluated for significant associations with bDFS.
• Results: Median PSA before RT was 0.69 ng/ml. Median radiation dose was 64.8 Gy. The 5-year actuarial bDFS was 45%. There were 32 patients with a minimum followup of 4 years (median 73 months) who experienced a 5-year bDFS rate of 43%. PSA before RT (p = 0.016), RT dose (p = 0.026), surgical margin involvement (p = 0.017) and Gleason score (p = 0.018) were identified as prognostic factors for bDFS. A significant association with bDFS was present at 5 years of 65%, 34% and 0% for PSA before RT less than 0.6, 0.6 to 1.2, and greater than 1.2 ng/ml, respectively (p = 0.036). Patients with PSA before RT less than 0.6 ng/ml and total RT dose greater than 64.8 Gy had improved bDFS at 5 years compared to all others (77% vs. 32%, p = 0.04). Of 60 patients 3 (5%) experienced chronic grade 3 toxicity.
• Conclusions: Optimal benefit from salvage RT was achieved in patients with a PSA less than 0.6 ng/ml and doses of RT greater than 64.8 Gy. Early treatment with a sufficiently high dose of RT maximizes the potential for salvage.
  
  
• Editorial Comment
  This paper defines the timing and indication for adjuvant radiotherapy after biochemical tumor recurrences following radical prostatectomy. In conclusion, patients do better if treated at an PSA below 0.69 ng/ml, with a local dose of at least 64.8 Gy, with Gleason scores below 7, and, interestingly, with positive surgical margins. A possible explanation for the letter fact is that patients with positive surgical margins have a higher likelihood of localized microscopic residual disease in the prostate bed. An increasing PSA would more easily indicate local progression of that microscopic disease, whereas increasing PSA in the margin negative group may indicate undetectable distant disease that would not be treated effectively with radiotherapy to the prostate bed. Altogether the results support an earlier the better approach to postoperative radiotherapy.

Dr. Andreas Böhle
Professor of Urology
HELIOS Agnes Karll Hospital
Bad Schwartau, Germany