Photodynamic diagnosis of positive margin during radical prostatectomy: Preliminary experience with 5‐aminolevulinic acid

Abstract

OBJECTIVES: To investigate the feasibility of intraoperative photodynamic diagnosis (PDD) by 5-aminolevulinic acid (ALA) for the identification of positive surgical margins (PSM) during retropubic radical prostatectomy (RRP) in patients with prostate cancer (PCa). METHODS: Intraoperative PDD was carried out in 16 patients with pathologically confirmed PCa by biopsy of the apex, or carrying >25% of probability of extraprostatic extension as defined by Japan PC Table. Before operation, 1.0 g of ALA was given orally. During open RRP, the resection margins inside the body were examined by PDD system with a fluorescence laparoscope. After their removal, 12 harvested prostates were divided and also investigated by PDD. Red fluorescent-positive lesions were biopsied and compared with the pathological result. RESULTS: All 16 patients were fluorescence-negative inside the body, and negative margins were pathologically confirmed during PDD. Among the 43 specimens of 12 cases obtained by biopsy under PDD, 11 specimens (25.6%) were pathologically diagnosed as malignant tissue (adenocarcinoma, 10 specimens; high grade prostatic intraepithelial neoplasia, 1 specimen) and 19 specimens (44.2%) were evaluated as positive fluorescence by PDD with a sensitivity of 81.8%, a specificity of 68.8% and a predictive accuracy of 72.1%. No side-effects were observed and the procedures were well tolerated. CONCLUSIONS: PDD mediated by ALA during RRP might be a feasible and safe modality for detection of surgical margins. Further prospective randomized studies with larger populations are required.