Open Access

ARTICLE

Is there a learning curve for photodynamic diagnosis of bladder cancer with hexaminolevulinate hydrochloride?

Stavros Gravas, Kostas Efstathiou, Ioannis Zachos, Michael D. Melekos, Vassilios Tzortzis

Department of Urology, University of Thessaly, Larissa, Greece
Address correspondence to Dr. Stavros Gravas, Department of Urology, University of Thessaly, Mezourlo 411 10, Larissa, Greece

Canadian Journal of Urology 2012, 19(3), 6269-6273.

Abstract

Introduction: To assess the learning curve for fluorescence cystoscopy using hexaminolevulinate hydrochloride (HAL) in patients with bladder cancer.
Material and methods: Fifty patients underwent bladder instillation with HAL. Two senior residents separately inspected the bladder using white light cystoscopy, followed by fluorescence cystoscopy, and mapped the lesions. An experienced photodynamic diagnosis (PDD)-trained urologist also performed both cystoscopies, mapped and resected or cold biopsied suspect lesions under the supervision of another experienced urologist. To evaluate the learning curve, patients were divided into five subgroups: group 1 (patients 1–10), group 2 (11–20), group 3 (21–30), group 4 (31–40), and group 5 (41–50). The kappa statistic was calculated to assess interobserver agreement between physicians, and the false positive rates of urologists and residents were also compared.
Results: Histologically verified tumors were diagnosed in 103 of 142 lesions identified by PDD. The interobserver agreement between urologists and residents was moderate, moderate, good, excellent, and excellent for group 1, 2, 3, 4, and 5, respectively. Both residents had higher false positive rates compared to urologists in all subgroups, although this difference did not reach statistical significance. In addition, the false positive rate of residents declined as the number of procedures increased.
Conclusions: Our data suggest that approximately 20 cases of HAL PDD are required to achieve good interobserver agreement between inexperienced and experienced operators, and excellent agreement is achieved after 30 cases. The false positive rate of inexperienced operators was comparable to that of experts and showed a gradual decrease with experience.

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