Application of cryoablation in animal models of bladder and muscle-invasive bladder cancer: a narrative review of current status and future perspectives

Background and objective: In patients diagnosed with bladder cancer (BC), muscle-invasive bladder cancer (MIBC) accounts for 25%, including tumors invading the intrinsic muscle layer (T2), surrounding tissues of the bladder (T3), or adjacent pelvic organs/structures (T4). Cryoablation promises to be a novel interventional oncology technique, which effectively induces cellular destruction through freezing and thawing cycles. In addition to the direct tumor-killing effect, it also has a tumor-immune effect. Although this technique has been widely used among solid tumors, including liver, lung, and breast cancer, there have been few studies on tumors of hollow organs, such as BC. Thus, we summarized the application of cryoablation in BC according to reports from animal models and clinical studies and predicted the future direction of this treatment.

Methods: A literature search was performed in the PubMed database for articles published in English between 2001 and 2024. The keywords used were: "muscle-invasive bladder cancer", "bladder cancer", "cryoablation", and "cryosurgery". In total, 42 articles were included. We also gathered imaging data from the Minimally Invasive Tumor Therapies Center of Beijing Hospital.

Key content and findings: Cryoablation for MIBC is a relatively safe, feasible, and promising minimally invasive treatment technique. Cryoablation as an adjuvant therapy with transurethral resection of bladder tumor (TURBT) is feasible and safe in T2 MIBC. It is able to achieve satisfactory local control. In T3-T4 MIBC, cryoablation can serve as a palliative treatment to reduce the tumor burden, but needs to be combined with other treatments to improve the prognosis.

Conclusions: This review presents a comprehensive overview of the current state and future perspectives of cryoablation in animal models of BC and MIBC, which might set a strong foundational knowledge base. Moreover, this novel approach could potentially revolutionize treatment paradigms if further validated.