Urine cytology is a simple method used for diagnosing and monitoring bladder cancer. Although it offers very high specificity, its sensitivity for detecting low-grade urothelial carcinoma is limited.

A phase III prospective, open-label, multicenter trial (SPP2C101 study, jRCT2080222877) was conducted with 60 patients—both primary and recurrent cases—from five universities. All patients underwent urine cytology within 14 days before transurethral resection of bladder tumors (TURBT), followed by either white light TURBT or photodynamic diagnosis (PDD)-assisted TURBT.

We analyzed the relationship between urine cytology class and the detection of carcinoma in situ (CIS) using white light or PDD. CIS was identified exclusively via PDD in some patients with cytology classified as class I and II (no malignant findings). Additionally, in class IV (cells strongly suspected to be malignant) and class V (atypical malignant cells present), PDD detected more CIS lesions than white light.

Across most preoperative urine cytology classes, PDD detected CIS cases that white light missed, both at the patient and sample level. Therefore, PDD should be considered during TURBT regardless of preoperative urine cytology results, provided the patient is suitable for this approach.

Bladder cancer

Carcinoma in situ (CIS)

Photodynamic diagnosis (PDD)

5-aminolevulinic acid hydrochloride

Transurethral resection of bladder tumors (TURBT)

© 2025 The Authors. Published by Elsevier B.V.