Diagnosis of bladder carcinoma using protoporphyrin IX fluorescence induced by 5-aminolaevulinic acid

OBJECTIVE: To report the results of a clinical study investigating the diagnosis of malignant and dysplastic bladder lesions by protoporphyrin IX (PPIX) fluorescence and to compare them with those from earlier studies. PATIENTS AND METHODS: The study included 55 patients with suspected bladder carcinoma (at initial diagnosis or at tumour follow-up visits); 130 bladder biopsies from 49 patients were classified by pathological analysis. All patients received an intravesical instillation of 50 mL of a 3% 5-aminolaevulinic acid (ALA) solution a mean of 135 min before cystoscopy, which was then performed under white and blue light. Malignant/dysplastic lesions showing red fluorescence under blue-light excitation were noted and the increase in detection rate calculated. RESULTS: There were 63 benign and 67 malignant/dysplastic areas biopsied; 10 malignant/dysplastic lesions (four transitional cell carcinoma, two carcinoma in situ, four dysplasia) were not detected during routine white-light cystoscopy but were identified under blue light. Fluorescence cystoscopy improved the overall diagnosis of malignant/dysplastic bladder lesions by 18% over standard white-light cystoscopy. The improvement was greater for dysplastic lesions and carcinoma in situ (50%). However, the improvement over standard cystoscopy was less than that found by other groups. CONCLUSION: The ALA-based fluorescence detection system significantly enhanced the diagnosis of malignant/dysplastic bladder lesions. However, determining the optimum drug exposure time requires further investigation using well-characterized instrumentation and study protocols, which would then allow comparison of the results from different groups.