RESUMEN
OBJECTIVE: To determine the selectivity of 5-aminolevulinic acid (5-ALA) as a photosensitizer to malignant prostatic cells in men undergoing radical retropubic prostatectomy. PATIENTS AND METHODS: Nineteen patients with localized prostate cancer were included in the study. Eighteen patients received 5-ALA and one patient did not receive it and was used as a control. The dose was 20mg /kg body weight, 15 patients received 5-ALA 4 hours before radical prostatectomy, two patients received it 2 hours before prostatectomy through a Ryle tube, and one patient received 5-ALA 12 hours before the operation. The removed prostates were examined for protoporphyrin IX (PpIX) fluorescence macroscopically, by fluorescence microscopy and by light microscopy. RESULTS: All carcinomas showed a clear evidence of PpIX-enrichment except in the control case. The enrichments were strong (++) in 15 cases and weak (+) in 3 cases. Two of those three cases were given 5-ALA two hours through a Ryle tube before excision of the prostate as well as the patient who was given 5-ALA 12 hours preoperatively. No PpIX enrichment was observed in the stroma of the prostate gland or in the benign tissue sections in any case (0/19). CONCLUSION: Oral 5-ALA is selectively concentrated in malignant cells of the prostate. This may lead to the clinical application of photodynamic therapy for localized prostate cancer.