Efficacy Evaluation of Submucosal Injection of Gemcitabine in Preventing Recurrence of Intermediate- and High-Risk Non-Muscle-Invasive Bladder Cancer: A Randomized, Single-Blind, Multicenter Clinical Study

Bladder cancer is a common malignant tumor of the urinary system. Globally, in 2023, there were approximately 610,000 new cases of bladder cancer and about 220,000 deaths attributed to the disease. In China, over the past two decades, the age-standardized incidence and prevalence rates of bladder cancer in men have increased by 71.79% and 195.38%, respectively. Over the last 15 years, the average annual mortality rate for male bladder cancer has risen by 3.84%, posing a serious threat to public health.

Bladder cancer is classified into non-muscle-invasive bladder cancer (NMIBC) and muscle-invasive bladder cancer (MIBC) based on whether the tumor invades the muscle layer. NMIBC accounts for approximately 75% of newly diagnosed bladder cancer cases. The standard treatment for NMIBC involves transurethral resection of bladder tumor (TURBT) followed by postoperative intravesical therapy. However, NMIBC often recurs within one year, with a recurrence rate as high as 60-70%, and 20-30% of cases progress to MIBC. Once bladder cancer advances to MIBC, it is characterized by rapid progression and a high tendency for metastasis. The standard treatment for MIBC is radical cystectomy with lymph node dissection, often accompanied by neoadjuvant or adjuvant chemotherapy. Traditional radical surgery for bladder cancer is highly invasive, associated with slow postoperative recovery and a high incidence of complications. The objective response rate for neoadjuvant or adjuvant chemotherapy is less than 50%. The 5-year survival rate for MIBC is below 60%, and for patients with distant metastasis, it drops significantly to just 5.4%.

In recent years, cancer immunotherapy, particularly immune checkpoint inhibitors, has advanced rapidly. However, immunotherapy also suffers from a low objective response rate, which is even below 30% in MIBC. Therefore, the high incidence, recurrence rate, and difficulty in curing bladder cancer remain significant challenges for both clinicians and patients.

TURBT is the standard surgical procedure for NMIBC. Intravesical therapy is a local adjuvant treatment used after TURBT to prevent recurrence. However, the efficacy of intravesical therapy is limited by inadequate drug absorption, resulting in insufficient local drug concentrations and suboptimal therapeutic outcomes. Moreover, postoperative intravesical therapy involves long-term, repeated invasive procedures, which often lead to complications such as urinary tract infections, bladder irritation, and urethral strictures. Improving the efficiency of drug utilization in intravesical therapy is a promising approach to address these issues. Enhancing drug absorption and prolonging the sustained-release effect of the agents could improve treatment efficacy while reducing the frequency of intravesical instillations, ultimately improving the prognosis of NMIBC, lowering recurrence rates, and reducing the risk of progression to MIBC. Submucosal injection of chemotherapeutic drugs offers a potential solution by increasing drug utilization efficiency and reducing complications associated with intravesical therapy.