Updates for the radiologist in non-muscle-invasive, muscle-invasive, and metastatic bladder cancer

Urologic Imaging of the Bladder: Cancers and Mimics

Bladder cancer (BC) represents a significant global health challenge with notable incidence and mortality rates. Despite treatment advancements, its management remains complex, requiring a multidisciplinary approach. Imaging techniques play a pivotal role in diagnosis, staging, and treatment planning by aiding lesion localization, differentiation, and assessment of tumor extent. Primary modalities like computed tomography and MRI offer detailed anatomic insights. Imaging provides valuable insights into tumor biology, vascular patterns, and molecular profiles, enabling personalized medicine strategies to optimize therapeutic efficacy and minimize adverse effects, crucial for improving BC management and prognosis.

Intravesical BCG therapy: implications for radiologists in abdominal imaging follow-up

This study reviews the intravesical Bacillus Calmette-Guérin therapy for treatment of non-muscle invasive bladder cancer including mechanism of action, dosing considerations, treatment success and surveillance. A variety of common and uncommon adverse effects are reviewed with a focus on abdominal -pelvic complications stratified into genitourinary and systemic categories. The complications included more common entities such as chemical cystitis, which has been reported to be present in approximately 35% of the patients to more serious but rare complications such as vascular involvement with only a few reported cases in the literature. For each complication, the pertinent imaging findings and available examples are provided. Additionally, it is important to consider the potential for recurrence or progression of bladder cancer in this patient population, with reported rates of 38.2% and 9.8%, respectively. This underscores the necessity of a thorough differential diagnosis when interpreting imaging findings related to these complications.

Muscle-invasive Urothelial Cancer: Association of Mutational Status with Metastatic Pattern and Survival

Background Muscle-invasive urothelial cancer (MIUC) is characterized by substantial genetic heterogeneity and high mutational frequency. Correlation between frequently mutated genes with clinical behavior has been recently demonstrated. Nonetheless, correlation between mutational status of MIUC and metastatic pattern is unknown. Purpose To investigate the association of mutational status of MIUC with metastatic pattern, metastasis-free survival (MFS), and overall survival (OS). Materials and Methods This single-center retrospective study evaluated consecutive patients with biopsy-proven MIUC who underwent serial cross-sectional imaging (CT, MRI, or fluorine 18 fluorodeoxyglucose PET/CT) between April 2010 and December 2018. Mutational status was correlated with location of metastases using the χ² or Fisher exact test. Mutational status and metastatic pattern were correlated with MFS and OS using univariable Cox proportional hazard models. High-risk (presence of TP53, RB1, or KDM6A mutation) and low-risk (presence of ARID1A, FGFR3, PIK3CA, STAG2, and/or TSC1 mutation and absence of TP53, RB1, or KDM6A mutation) groups were determined according to existing literature and were correlated with MFS and OS by using multivariable Cox proportional hazard models. Results One hundred three patients (mean age, 72 years ± 11 [standard deviation]; 81 men) were evaluated. Seventeen of 103 (16%) patients had metastatic disease at diagnosis; 38 of 103 (37%) developed metastatic disease at a median of 5.9 months (interquartile range, 0.8-28 months). TP53 mutation (seen in 58 of 103 patients, 56%) was associated with lymphadenopathy (relative risk [RR]: 1.7; 95% confidence interval [CI]: 1.2, 2.4; P = .002) and osseous metastases (RR: 1.9; 95% CI: 1.6, 2.3; P = .02); RB1 mutation (seen in 19 of 103 patients, 18.4%) was associated with peritoneal carcinomatosis (RR: 5.9; 95% CI: 3.8, 9.2; P = .03). ARID1A mutation was associated with greater OS (hazard ratio [HR]: 3.1; 95% CI: 1.2, 10; P = .01). At multivariable Cox analysis, the high-risk group (TP53, RB1, and/or KDM6A mutations) was independently associated with shorter MFS (HR: 3.5, 95% CI: 1.3, 12; P = .009) and shorter OS (HR: 3.1; 95% CI: 1.2, 10; P = .02). Conclusion Mutational status of muscle-invasive urothelial cancer has implications on metastatic pattern, metastasis-free survival, and overall survival. © RSNA, 2020 Online supplemental material is available for this article. See also the editorial by Choyke in this issue.

Diagnosis of bladder cancer using 18F-labeled α-methyl-phenylalanine tracers in a mouse model

OBJECTIVE

Although 2-¹⁸F-fluoro-2-deoxy-glucose (¹⁸F-FDG) has established roles in the diagnosis of a variety of cancers, it has limited value in the detection of primary/recurrent lesions in the bladder, mainly because of interference by the pooled radioactivity in the urine. Our previous study revealed promising properties of L- and D-2-¹⁸F-α-methyl-phenylalanine (2-¹⁸F-FAMP) as radiotracers; i.e., their rapid blood clearance and low renal accumulation. In the present study we evaluated the utility of L- and D-2-¹⁸F-FAMP for imaging bladder cancer in a mouse model.

METHODS

We used the human bladder cancer cell line HT1376 to prepare a bladder cancer xenograft model in mice bearing both orthotopic and subcutaneous tumors. Biodistribution and PET imaging studies were performed at 1 and 3 h after injection of L-2-¹⁸F-FAMP or D-2-¹⁸F-FAMP. ¹⁸F-FDG was used as a control.

RESULTS

At 1 h after injection, greater accumulations of both L-2-¹⁸F-FAMP and D-2-¹⁸F-FAMP were observed in the orthotopic tumors compared to ¹⁸F-FDG. The orthotopic tumor-to-muscle ratio of D-2-¹⁸F-FAMP was significantly higher than that of ¹⁸F-FDG (p < 0.01), because of the rapid blood clearance of D-2-¹⁸F-FAMP. L-2-¹⁸F-FAMP showed the highest subcutaneous tumor-to-muscle ratio (p < 0.01) due to its high subcutaneous tumor uptake. Compared to L-2-¹⁸F-FAMP, D-2-¹⁸F-FAMP exhibited faster clearance and lower kidney accumulation. In the PET imaging studies, L- and D-2-¹⁸F-FAMP both clearly visualized the orthotopic bladder tumors at 1 h after injection.

CONCLUSION

Our study showed that L-2-¹⁸F-FAMP and D-2-¹⁸F-FAMP have the potential to detect bladder cancer.

Advanced urothelial cancer: a radiology update

The recent genomic characterization of urothelial carcinoma by the Cancer Genome Atlas Project, made possible by the introduction of high throughput, reduced cost, and sequence analysis, has shed new insights on the biology of advanced disease. In addition, studies on imaging of advanced urothelial carcinoma have widened the knowledge on disease presentation and on pattern of metastatic spread and their correlation with the underlying biology of urothelial carcinoma. The wide range of treatments for advanced urothelial cancer, including combined chemotherapy regimens and immune checkpoint inhibitors, each result in treatment class-specific patterns of response and adverse events. Results of studies point to the need for a reliable biomarker, perhaps with imaging, that predicts prognosis and treatment response to systemic treatment, and can be used to select the most effective treatment while minimizing toxicity. This review of advanced urothelial cancer introduces the latest advances in genetic profiling, the current role of imaging, the radiographic appearance of treatment response and their toxicities, and details potential future areas of imaging research.

[Influence of immunomodulators on urological imaging]

BACKGROUND

Immune checkpoint inhibitors (ICI) have led to great advances in the therapy of metastatic renal cell and urothelial carcinoma. Currently ICI are approved for the first-line therapy of cisplatin-unfit patients (Atezolizumab, Pembrolizumab) and second-line therapy in patients with metastasized urothelial cancer (Atezolizumab, Nivolumab, Pembrolizumab). For the therapy of metastasized RCC, Nivolumab is approved as a second-line therapy and in combination with the CTLA‑4 antibody Ipilimumab as a first-line therapy.

OBJECTIVES

What does the optimized radiological follow-up and therapy response assessment for ICI, which differ in their pathways from common chemotherapeutics and anti-angiogenetic drugs, look like? What strategies are needed to meet the upcoming challenges concerning interpretation of the acquired images?

METHODS

A systematic literature search was carried out for urothelial and renal cell carcinoma.

RESULTS

Immune-related response criteria have been introduced to better characterize the imaging changes occurring under ICI, as monitoring response to immunotherapy still relies on RECIST.

CONCLUSIONS

To properly identify and predict response after treatment with ICI, additional studies with long-term follow-ups are needed. Because of the growing use of ICI, radiologists and urologist should be familiar with common imaging findings (such as pseudo progress) under immunotherapy to correctly interpret these findings in daily routine.

microRNA‑145 modulates migration and invasion of bladder cancer cells by targeting N‑cadherin

MicroRNA (miRNA)‑145 has been demonstrated to serve a role in several types of tumors, however, the potential molecular mechanism of action of miRNA‑145 in bladder cancer metastasis remains to be elucidated. This study aimed to investigate the potential modulation of miRNA‑145 in bladder carcinoma and elucidate the underlying molecular mechanism. The expression of miRNA‑145 in bladder adenocarcinoma tissues and bladder cancer cells was measured by reverse transcription‑quantitative polymerase chain reaction. miRNA‑145 mimics and inhibitor were transfected into bladder cancer (BC) cells to determine the role of miRNA‑145 on cell motility and invasion measured by wound healing and transwell assays. Luciferase assay was performed to confirm whether N‑cadherin was the direct target of miRNA‑145. Subsequently, expression of N‑cadherin and matrix metalloproteinase‑9 (MMP9) in BC cells were detected by western blot analysis. miRNA‑145 was significantly downregulated cells and tissues from patients with BC, compared with healthy controls. miRNA‑145 markedly inhibited the ability of BC cells to migrate and invade. Furthermore, N‑cadherin was identified as a target of miRNA‑145 in BC cells. MMP9, acting downstream of N‑cadherin, was downregulated in BC cells by miRNA‑145. In the present study, miRNA‑145 suppressed the migration and invasion of BC cells by regulating N‑cadherin. The results of the present study indicated that miRNA‑145 may function as a tumor suppressor and may have a potential to be a diagnostic and predictive biomarker, and a therapeutic target for treatment of BC.