Photodynamic diagnosis using 5-aminolevulinic acid for the detection of positive surgical margins during radical prostatectomy in patients with carcinoma of the prostate: a multicentre, prospective, phase 2 trial of a diagnostic procedure

Abstract

Background: Surgical margin status after radical prostatectomy (RP) is a significant risk factor for tumour recurrence. It is an intriguing concept to find a fluorescence marker for photodynamic diagnosis (PDD) to make tumour margins visible during surgery.

Objective: To investigate the feasibility of identification of positive surgical margins (PSM) during open retropubic or endoscopic extraperitoneal RP by 5-aminolevulinic acid (5-ALA)-induced protoporphyrin IX (PpIX) to enhance surgical radicality.

Design, setting, and participants: Thirty-nine patients (Gleason score 6-10, prostate-specific antigen [PSA] 2.3-120 ng/ml) received 20 mg/kg of body weight of 5-ALA orally and underwent RP (24 endoscopic extraperitoneal, 15 open retropubic).

Measurements: A PDD-suitable laparoscopy optic (Karl-Storz GmbH, Tuttlingen, Germany) with a yellow long-pass filter was coupled to a fibre-optic light cord with an excitation light source (380-420 nm, D-Light, Karl-Storz GmbH, Tuttlingen, Germany) for fluorescence excitation of PpIX and to a PDD-suitable camera for video and photo documentation by the AIDA DVD system (Karl-Storz GmbH, Tuttlingen, Germany).

Results and limitations: There were more false-negative cases in the open group (four vs two) than in the endoscopic group but more false-positive cases in the endoscopic group (two vs none) than in the open group. The overall sensitivity and specificity were 56% and 91.6%, respectively. The sensitivity of the endoscopic cases was much higher (75% vs 38%) than for the open cases, while the specificity was higher for the open group (88.2% vs 100%).

Conclusions: PDD with 5-ALA-induced PpIX during RP might be a feasible and effective method for reducing the rate of PSM. The technique seems to be more practicable during endoscopic RP rather than open RP. Further clinical studies with higher patient volumes and further development of the technique seem justified.

Trial registration: EudraCT: 2005-004406-93.