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

Abstract

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). 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. 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. 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.