Takeshi Sano, Chisato Ohe, Takahiro Nakamoto, Takashi Yoshida, Hisanori Taniguchi, Masaaki Yanishi, Hidefumi Kinoshita
OBJECTIVES: To demonstrate the diagnostic performance of photodynamic diagnosis (PDD) for bladder cancer using oral 5-aminolaevulinic acid in patients with or without a history of intravesical Bacillus Calmette-Gu��rin (BCG) therapy, and to investigate the potential causes of false-positive results.
METHODS: This retrospective study included 110 patients with suspected non-muscle-invasive bladder cancer who underwent PDD. Among them, 80 patients had no history of BCG therapy (BCG-na��ve group) and 30 had received BCG therapy (BCG group). Pathological examination of false-positive and true-negative PDD samples was performed.
RESULTS: In the BCG-na��ve group, 215 samples were PDD-positive, of which 53 (24.7%) showed no malignancy. In the BCG group, 94 samples were PDD-positive, of which 51 (54.3%) showed no malignancy. The sensitivity, specificity, positive predictive value, and negative predictive value of PDD in the BCG-na��ve versus BCG group were 70.1 versus 76.8, 82.6 versus 56.0, 75.3 versus 45.7, and 78.5 versus 83.3, respectively. Only six of 100 samples (6%) with false-positive PDD results showed precancerous findings. Irrespective of whether patients had received intravesical BCG therapy, >���90% of the samples with false positivity in PDD showed reactive changes, whereas 22 of 95 samples (23.2%) with true negativity in PDD showed reactive changes (p���<���0.0001).
CONCLUSIONS: Both the specificity and positive predictive value of PDD were lower in the BCG group than in the BCG-na��ve group. In most false-positive PDD samples, reactive changes, rather than precancerous findings, were observed-even in the BCG-na��ve group.
