title: Reduced specificity of 5-ALA induced fluorescence in photodynamic diagnosis of transitional cell carcinoma after previous intravesical therapy.
abstract: OBJECTIVE
  Photodynamic diagnosis (PDD) for the detection of bladder cancer has become a diagnostic tool in several hospitals. Several studies have reported different rates of false positive biopsies using 5-aminolevulinic acid induced fluorescence. In this study we evaluated the effect of previous intravesical therapy on the false positive biopsy rate.
  
  
  METHODS
  Two hours prior to endoscopy 1.5g ALA dissolved in 50ml 1.4% NaHCO(3) solution was instilled intravesically. For fluorescence excitation a blue light source (D-light, Karl Storz) was used. Under white and fluorescence light guidance, tumor locations were recorded, cold cup biopsies were taken and tumors were resected. Patients were divided into 3 groups, last intravesical therapy (IVT) less than 6 months prior to PDD, last IVT longer than 6 months before PDD and no previous IVT.
  
  
  RESULTS
  In total 917 biopsies were taken in 249 procedures of fluorescent and non-fluorescent areas. White light endoscopy revealed 270 and PDD 378 of in total 390 tumors, resulting in a sensitivity of 97% and specificity of 49% for PDD. Pathologic evaluation considered 270 fluorescent biopsies as false positive. The rate of false positive biopsies was 25.7% in the group No IVT, 30.6% in the group PDD-IVT >6 months, whereas in the group "within 6 months after intravesical therapy" the rate was 39.6% (p<0.025). When premalignant lesions such as dysplasia II are considered tumor the difference between the groups is even more significant (p<0.001).
  
  
  CONCLUSIONS
  The procedure has a high sensitivity for superficial bladder cancer and decreases the number of overlooked lesions. Recent intravesical therapy results in significantly more false positive fluorescent biopsies. Since patient outcome might predominantly be determined by the early detection and subsequent treatment of (pre)malignant tissue we suggest that PDD is justified even shortly after intravesical therapy.
authors.affiliation: Department of Biomedical Engineering, University Medical Center Utrecht, Heidelberglaan 100, 3508 GA Utrecht, The Netherlands. m.grimbergen@azu.nl
authors.forename: M C M
authors.initials: MC
authors.lastname: Grimbergen
authors.forename: C F P
authors.initials: CF
authors.lastname: van Swol
authors.forename: T G N
authors.initials: TG
authors.lastname: Jonges
authors.forename: T A
authors.initials: TA
authors.lastname: Boon
authors.forename: R J A
authors.initials: RJ
authors.lastname: van Moorselaar
mesh_terms: D000283:Administration, Intravesical; D000368:Aged; D000369:Aged, 80 and over; D000622:Aminolevulinic Acid; D002295:Carcinoma, Transitional Cell / Q000175:diagnosis / Q000473:pathology* / Q000628:therapy*; D015331:Cohort Studies; D003558:Cystoscopy / Q000379:methods; D005189:False Positive Reactions; D005260:Female; D005453:Fluorescence; D006801:Humans; D008297:Male; D008875:Middle Aged; D009163:Mycobacterium bovis; D017319:Photosensitizing Agents; D011336:Probability; D011446:Prospective Studies; D012680:Sensitivity and Specificity; D001749:Urinary Bladder Neoplasms / Q000175:diagnosis / Q000473:pathology* / Q000628:therapy*
chemical_list: D017319:Photosensitizing Agents; D000622:Aminolevulinic Acid