Hypothesis / aims of study
Non-muscle invasive bladder cancer (NMIBC) represents approximately 75–85% of newly diagnosed bladder cancer cases [1]. Despite its less invasive nature, NMIBC carries high rates of recurrence and progression, posing significant management challenges. Standard treatment begins with transurethral resection of bladder tumor (TURBT), often followed by intravesical therapies such as Bacillus Calmette–Guérin (BCG), which is the gold standard post-TURBT, or chemotherapy [1]. Modifiable risk factors—particularly occupational and lifestyle exposures—play a key role in disease onset and recurrence but are often overlooked in treatment strategy [2].
This scoping review aims to compare the efficacy of common treatment modalities for NMIBC, evaluate how modifiable risk factors such as occupational exposures and lifestyle factors contribute to disease risk and clinical outcomes, and identify several knowledge gaps in the management of NMIBC, while informing both clinical decision-making and preventive strategies.
Study design, materials and methods
Following the PRISMA-ScR framework, a systematic search was conducted using PubMed, Google Scholar and Cochrane Library databases for articles published between 2000 and 2024, which yielded 240 studies. Eligible studies included randomized controlled trials, cohort studies, and systematic reviews in English that addressed either NMIBC treatment outcomes or risk factors. Data were extracted and synthesized on treatment efficacy, recurrence, complications, and exposure-related risk. Quality appraisal was performed using validated tools, including the Cochrane Risk of Bias Tool and Newcastle-Ottawa Scale.
Results
Twenty studies met inclusion criteria. TURBT alone showed recurrence rates of up to 80%, necessitating adjuvant treatment. BCG provided superior recurrence-free survival in high-risk patients, reducing recurrence and progression by up to 60%. Intravesical chemotherapy (e.g., mitomycin C, gemcitabine) was effective in intermediate-risk NMIBC, with 20–40% recurrence reduction. In terms of complications, BCG therapy had the highest rate (up to 30%), followed by TURBT and combination therapies (up to 20%). Intravesical chemotherapy had complication rates below 10%. Occupational exposures such as aromatic amines and PAHs increased NMIBC risk by 2.5–4 times. Smoking accounted for up to 50% of cases, while other risk factors included low fluid intake, high red meat consumption, obesity, and chronic infections.
Interpretation of results
The findings suggest that BCG remains the most effective treatment for high-risk NMIBC, while intravesical chemotherapy is optimal for intermediate-risk disease. TURBT alone is insufficient due to high recurrence rates. Additionally, the influence of modifiable risk factors—especially occupational and lifestyle exposures—indicates that NMIBC prevention strategies should extend beyond clinical intervention to include public health and patient education components.