MP63-17: Photodynamic diagnosis (PDD) directed biopsies vs white light bladder mapping in patients with positive cytology and negative preoperative workup: an international multicenter retrospective study
Department of Surgical Science, University of Studies of Torino
Introduction: Bladder Carcinoma in situ (CIS) is a flat, non-vegetating, high-grade tumor and is associated with a high risk of progression to muscle invasive cancer (MIBC), especially if not timely diagnosed and treated. Since it may be often not visible with white light cystoscopy (WL), international guidelines therefore recommend the use of bladder mapping in case of suspected CIS (positive urine cytology and negative preoperative workup). Photodynamic diagnosis (PDD) has been shown to increase the sensitivity in diagnosing CIS compared to WL cystoscopy. However, a direct comparison between PDD-guided biopsies (PDD-GB) and WL bladder mapping (WL-M) is lacking. The aim of our study is therefore to compare the diagnostic capability of PDD-GB versus that of WL-M. Methods: A retrospective analysis was conducted from March 2018 to May 2022 at two European referral Centers. Overall, 73 patients were enrolled according to the following inclusion criteria: positive urinary cytology or gross hematuria and negative flexible cystoscopy and / or negative CT scan. Patients underwent either PDD-GB or WL-M, as per international guidelines. The main endpoint of the study was the diagnostic accuracy in the diagnosis of bladder cancer (BCa) and, particularly, of CIS. Recurrence-free and progression-free survival were investigated as secondary endpoint. Results: Overall, 50 patients (68%) underwent (PDD-GB) and 23 (32%) WL-M. No differences in baseline characteristics were observed among the two groups. BCa was found in 16 patients (32%) among the PDD-GB group and in 8 patients (34.78%) among the WL-M group (p = 0.8); CIS was found in 11 (22%) patients undergoing PDD-GB and in 6 patients (26.09%) in the WL-M group (p=0.7). On univariable logistic regression the type of intervention (PDD-GB vs WL-M) was not associated with either BCa or CIS diagnosis (all p>0.05). Disease recurrence was found in 18 patients, but no statistically significant differences were observed among the two groups (p=0.3); disease progression was found in 7 patients and, again, no differences were observed (p=0.3). Conclusions: We did not observe statistically significant differences between the PDD-GB group and the WL-M group in the diagnosis of BCa and CIS. WL-M remains a valid alternative to PDD-GB in patients with suspected CIS. The main limitations of this study are inherent its retrospective nature and the small sample size. SOURCE OF Funding: None
