# Utility of blue-light cystoscopy and tumor-informed ctDNA for management of recurrent high-risk NMIBC with prostatic urethral involvement: A case report

## TL;DR

This case report shows how blue-light cystoscopy and ctDNA testing can help manage a rare and complex bladder cancer case with prostatic urethral involvement.

## Contribution

Demonstrates the combined utility of blue-light cystoscopy and tumor-informed ctDNA in staging and managing high-risk NMIBC with PUI.

## Key findings

- Blue-light cystoscopy detected additional CIS and high-grade T1 lesions not visible with white light.
- Tumor-informed ctDNA testing showed no molecular residual disease, supporting favorable staging.
- Radical cystectomy confirmed no residual tumor despite complex clinical features.

## Abstract

Non–muscle-invasive bladder cancer (NMIBC) with prostatic urethral involvement (PUI) is rare and difficult to manage, especially after intravesical therapy or pelvic radiation. We report a 78-year-old man with recurrent high-risk NMIBC and PUI after bacillus Calmette–Guérin and mitomycin C. Blue-light cystoscopy (BLC) during restaging identified additional carcinoma in situ and high-grade T1 disease not seen with white light. Histopathology showed no stromal invasion, and tumor-informed circulating tumor DNA (ctDNA) testing was negative, indicating no molecular residual disease. Despite favorable findings, the patient elected radical cystectomy, which revealed no residual tumor. This case highlights the complementary roles of BLC and ctDNA.

•Blue-light cystoscopy improved detection of CIS and high-grade lesions in recurrent NMIBC.•Tumor-informed ctDNA (Signatera™) provided molecular confirmation of low residual disease.•Combined use of BLC and ctDNA enhanced staging accuracy in NMIBC with prostatic urethral involvement.•Multimodal evaluation guided individualized management in a very high-risk, BCG-unresponsive patient.•Radical cystectomy pathology confirmed no residual carcinoma despite complex disease features.

Blue-light cystoscopy improved detection of CIS and high-grade lesions in recurrent NMIBC.

Tumor-informed ctDNA (Signatera™) provided molecular confirmation of low residual disease.

Combined use of BLC and ctDNA enhanced staging accuracy in NMIBC with prostatic urethral involvement.

Multimodal evaluation guided individualized management in a very high-risk, BCG-unresponsive patient.

Radical cystectomy pathology confirmed no residual carcinoma despite complex disease features.