Reply to Jeremy Y.C. Teoh, Thomas R.W. Herrmann, and Marek Babjuk's Letter to the Editor re: Valeria Panebianco, Yoshifumi Narumi, Ersan Altun, et al. Multiparametric Magnetic Resonance Imaging for Bladder Cancer: Development of VI-RADS (Vesical Imaging-Reporting and Data System). Eur Urol 2018;74:294–306

Recurrence mechanisms of non-muscle-invasive bladder cancer - a clinical perspective

Non-muscle-invasive bladder cancer (NMIBC) is an early-stage cancer without invasion into the detrusor muscle layer. Transurethral resection of bladder tumour (TURBT) is a diagnostic and potentially curative procedure for NMIBC, but has some limitations, including difficulties in ascertaining complete tumour removal upon piecemeal resection and the possibility of tumour re-implantation after the procedure. The oncological control of NMIBC is far from satisfactory, with a 1-year recurrence rate of 15-61%, and a 5-year recurrence rate of 31-78%. Various recurrence mechanisms have been described for NMIBC, such as undetected tumours upon cystoscopy, incomplete resection during TURBT, tumour re-implantation after TURBT, drop metastasis from upper tract urothelial carcinoma and field change cancerization. Understanding the recurrence mechanisms from a clinical perspective has strong implications for the optimization of NMIBC oncological outcomes, as a cure for patients with NMIBC can only be achieved by tackling all possible recurrence mechanisms in a comprehensive manner.

Preliminary Exploration of the Application of Vesical Imaging-Reporting and Data System (VI-RADS) in Post-treatment Patients With Bladder Cancer: A Prospective Single-Center Study

BACKGROUND

Vesical Imaging-Reporting and Data System (VI-RADS) has been shown to be effective in diagnosing muscle invasion of bladder cancer (BC) in primary patients.

PURPOSE

To evaluate the diagnostic efficacy of VI-RADS in a BC target population which included post-treatment patients, and to determine the repeatability.

STUDY TYPE

Prospective.

POPULATION

Seventy-three patients (42 with primary BC, 31 with post-treatment BC).

FIELD STRENGTH/SEQUENCE

3.0 T MRI with propeller fast spin-echo T₂ WI, echo planer imaging diffusion-weighted imaging (DWI), and dynamic contrast-enhanced imaging (DCEI).

ASSESSMENT

VI-RADS scores were independently assessed by five radiologists with different levels of experience. The diagnostic efficiency in each group (primary and post-treatment) and of each radiologist was assessed.

STATISTICAL TESTS

Sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV), and area under the curve (AUC) in receiver operating characteristic curve analysis were calculated to evaluate VI-RADS diagnostic performance. Interobserver agreement was assessed using weighted Kappa statistics. A P value <0.05 was considered statistically significant.

RESULTS

At the corresponding cut-off, AUC values of three groups range from 0.936 to 0.947 and AUC values of five observers range from 0.901 to 0.963. There was no significant difference between the AUCs in the primary and post-treatment groups (P = 0.870). The cut-off of the whole group and the post-treatment group was ≥4, and the cut-off of the primary group was ≥3. The Kappa values of interobserver agreements range from 0.709 to 0.923.

CONCLUSIONS

After expanding the target population to include post-treatment patients, VI-RADS still has good diagnostic efficacy and repeatability. VI-RADS could potentially be a preoperative staging tool for post-treatment patients.

LEVEL OF EVIDENCE

1 TECHNICAL EFFICACY STAGE: 2.