Efficacy and safety of cryoablation procedures using mouse models of bladder cancer.

The standard treatment for muscle-invasive bladder cancer (MIBC), total cystectomy, is highly invasive. Decreased quality of life (QOL) due to urinary diversion is a serious problem in patients with MIBC. In this study, we examined the therapeutic efficacy of cryoablation for MIBC in a mouse model of orthotopic bladder cancer and investigated its usefulness as a new treatment modality. Murine bladder cancer models were established by administering the chemical carcinogen N-butyl-N-(4-hydroxybutyl) nitrosamine. We monitored physiological parameters, including body weight, water intake, urine output, and urination frequency. Cryoablation was then performed on the tumor-bearing mice, and postoperative tumor progression and histological changes were evaluated. Physiological responses were tracked for up to post operative days 28 (POD 28) and compared with those in a non-operative group. Additionally, levels of CD4+ and CD8+ T cells were measured to evaluate immune activation following cryoablation. After cryoablation in the bladder cancer mouse model, we observed the following: (i) localized frostbite-induced injury to the muscle layer, which was gradually replaced by adjacent tissue; (ii) preservation of spontaneous urination post-surgery; and (iii) no procedure-related mortality. Moreover, a significant increase in CD4+ and CD8+ T cells was detected at POD 28. The efficacy, safety, and immune activation potential of cryoablation were confirmed in an orthotopic murine model of bladder carcinoma. Cryoablation for MIBC shows promise as a novel therapeutic approach for radical and bladder-sparing treatment with the potential to reduce metastatic disease.