Sweden: CTU with CMP and Urinary Bladder Cancer

Computed tomography-urography (CTU) with cortico-medullary phase (CMP) can rule out urinary bladder cancer (UBC) with high accuracy, says a recent study in the journal BMC Urology. It might be reasonable to omit cystoscopy in case of negative CTU, but future confirmative studies with possibly refined techniques will be needed.

The European Society of Urogenital Radiology (ESUR) defines CTU as a multiphasic imaging modality for the urinary tract, including the urinary bladder, using an intravenous administration of a contrast medium.

Urinary bladder cancer is one of the most commonly diagnosed cancers in the world. Its most common sign is macroscopic hematuria, which is investigated by cystoscopy and CTU. Currently, cystoscopy cannot be replaced by cytology or by any other non-invasive test, while CTU can be done only in certain cases, e.g., multiple or high-risk tumors.

Against the above background, Suleiman Abuhasanein, University of Gothenburg, Göteborg, Sweden, and colleagues aimed to evaluate the diagnostic accuracy of computed tomography-urography to rule out urinary bladder cancer and whether patients thereby could omit cystoscopy.

The study included all patients evaluated for macroscopic hematuria with CTU with CMP and cystoscopy between 1st November 2016 and 31st December 2019. From this study cohort, a study group consisting of all UBC patients and a control group of 113 patients were randomly selected from all patients in the study cohort without UBC.

CTUs were reviewed independently by two radiologists blinded to all clinical data. CTUs were categorized as positive, negative, or indeterminate. For the study cohort, diagnostic accuracy and proportion of potential omittable cystoscopies were calculated by generalizing the results from the study group.

The study cohort consisted of 2195 patients, 297 of which were in the study group (UBC group, n = 207 and control group, n = 90).

Study Findings

• Inter-rater reliability was high (κ 0.84).
• Evaluation of CTUs showed that 174 patients were assessed as positive (showing UBC), 46 patients as indeterminate (not showing UBC but with limited quality of CTU), and 77 patients as negative (not showing UBC with good quality of CTU).
• False negative rate was 0.07, false positive rate was 0.01, and negative predictive value was 0.99.
• The area under the curve was 0.93.
• Only 2.9% (3/102) with high-risk tumors and 11% (12/105) with low- or intermediate-risk tumors had a false negative CTU.
• Cystoscopy could potentially have been omitted in 57% (1260/2195) of all evaluations.

The researchers conclude, "CTU with CMP can exclude UBC with high accuracy. It might be reasonable to omit cystoscopy for the majority of patients with a negative CTU, but prospective confirmative studies with possibly refined techniques and protocols for repeated hematuria are needed."

Reference

Abuhasanein, S., Hansen, C., Vojinovic, D. et al. Computed tomography urography with corticomedullary phase can exclude urinary bladder cancer with high accuracy. BMC Urol 22, 60 (2022). https://doi.org/10.1186/s12894-022-01009-4