Kidney-preserving tumour resection in renal cell carcinoma with photodynamic detection by 5-aminolaevulinic acid: preclinical and preliminary clinical results

Objective To identify the outer border of a renal cell carcinoma (RCC) duri ng a kidney-preserving tumour resection by photodynamically detecting RCC a fter the exogenous administration of 5-aminolaevulinic acid (ALA) in an ani mal model and in humans, Patients, materials and methods Human RCC was xeno-transplanted subcutaneou sly and orthotopically into the kidneys of nude mice. ALA was then administ ered orally or intravenously (100-400 mg/kg body weight). The tumours were removed and examined macroscopically and microscopically for fluorescence, and the concentrations of protoporphyrin IX (PPIX) evaluated In the subcuta neous tumours. In a pilot study, nine patients with RCC of <4 cm diameter u nderwent partial nephrectomy, 20 mg ALA/kg body weight was given orally 4 h before surgery, During the operation, the macroscopic fluorescence of the tumours was evaluated and any side-effects recorded. Results In the mouse model, the RCC fluoresced in all rumours, both macro- and microscopically, reaching a maximum 1.5 h after intravenous and 4 h aft er oral administration. The tissue concentrations of PPIX in the subcutaneo us tumours were also maximal 4 h after oral administration, In the patients undergoing surgery, the RCC also fluoresced clearly and was sufficiently i ntense to identify the outer margins of the tumours for kidney-preserving t umour resection. There were no side-effects of the ALA with the dosages and methods of administration used. Conclusion The photodynamic detection of RCC with ALA facilitates the ident ification of tumour margins in man and in the mouse model, producing no und esirable side-effects, It may be helpful in determining the boundaries of t he resected tissue when carrying out conservative kidney-preserving surgery .