Bladder cancer is a common malignancy in the urinary system, ranking 11th in cancer
incidence in China (3.48/100,000), with male incidence ranking 8th (5.70/100,000). It is
classified as non-muscle-invasive bladder cancer (NMIBC) or muscle-invasive bladder
cancer (MIBC) based on muscle involvement. About 75% of patients are initially diagnosed
with NMIBC, with Ta, T1, and Tis stages comprising 70%, 20%, and 10%, respectively.
With the advancement of magnetic resonance imaging (MRI), its role in bladder cancer
diagnosis and staging has expanded. Multiparametric MRI (MpMRI) enhances staging accuracy
with better anatomical visualization. In 2018, Valeria et al. introduced the VI-RADS
scoring system, which uses MpMRI to predict tumor stage. Retrospective studies by Wang et
al. found that all tumors with a VI-RADS score of 1 were NMIBC, and 95.1% of tumors with
a score of 2 were also NMIBC. A VI-RADS score of ≤2 can be used to identify NMIBC with
high sensitivity.
NMIBC shows varied risks for recurrence and progression based on tumor characteristics
like size, stage, grade, and multiplicity. The European Association of Urology (EAU) risk
stratification system, established in 2021, classifies NMIBC into low-, intermediate-,
high-, and very-high-risk groups. Transurethral resection of bladder tumor (TURBT) is the
primary diagnostic and therapeutic approach for most NMIBC cases. However, residual
tumors can remain after the first TURBT. For Ta and T1 tumors, 17%-72% and 33%-78% of
cases show residual disease during second resection, respectively. Re-staging TURBT for
T1 tumors improves prognosis. Studies show that second TURBT offers longer
recurrence-free survival (47 months) compared to a single TURBT (12 months). The 5-year
progression rate was 6.5% with second TURBT, compared to 23.5% with a single procedure.
Following TURBT, floating and residual tumor cells may lead to recurrence. Immediate
postoperative bladder instillation of chemotherapy (e.g., pirarubicin, epirubicin,
doxorubicin, mitomycin C, gemcitabine) significantly reduces recurrence in low-risk NMIBC
but is less effective for intermediate- and high-risk NMIBC. For intermediate-risk NMIBC,
maintenance chemotherapy is recommended, and for high-risk NMIBC, BCG immunotherapy is
preferred. Both maintenance chemotherapy and BCG instillation reduce recurrence in these
groups. Mitomycin C offers comparable efficacy to BCG with fewer side effects.
For patients in the very-high-risk group, immediate radical cystectomy is recommended
because delayed cystectomy leads to poorer cancer-specific survival. High-risk NMIBC
patients may undergo 1-3 years of BCG therapy or immediate cystectomy if necessary.
Large-volume NMIBC (≥5 cm) presents significant challenges in treatment. TURBT for large
tumors often leads to difficulties in resection due to excessive bleeding, unclear
vision, and increased risk of bladder wall injury. Larger tumors also increase the risk
of tumor cell seeding and metastasis. Tumor size (≥3 cm) is an independent risk factor
for early recurrence and progression, leading some experts to recommend immediate radical
cystectomy for large-volume NMIBC.
Radical cystectomy is a high-risk procedure with complication rates of 28%-64% and
mortality rates of 2.5%-2.7%. It also requires urinary diversion, which can significantly
impact a patient's physical, psychological, and social well-being. Patients often face
lifelong use of urinary collection devices, reducing their quality of life. Given the
impact of radical cystectomy, bladder-sparing strategies have gained attention. These
approaches aim to preserve the bladder while controlling tumor growth, maintaining the
patient's quality of life.
Currently, no formal guidelines exist for bladder-sparing treatment of large-volume
NMIBC. However, a 2022 Chinese consensus emphasizes maximal TURBT followed by adjuvant
therapy to reduce recurrence and progression. Intravesical chemotherapy, particularly BCG
and mitomycin C, is a key part of postoperative management. In the era of immunotherapy,
PD-1/PD-L1 inhibitors are emerging as essential components of bladder-sparing strategies.
Pembrolizumab, for example, has shown a 41% complete response rate in BCG-unresponsive
NMIBC, leading to its FDA approval for carcinoma in situ patients who are ineligible or
unwilling to undergo radical cystectomy.
Although neoadjuvant chemotherapy is not yet included in NMIBC guidelines, its success in
MIBC suggests potential benefit for NMIBC. Neoadjuvant chemotherapy improves survival by
5%-10% and reduces mortality by 16%-33%. After achieving a pathological complete response
(pT0), patients can avoid radical cystectomy, with a 5-year survival rate of 90%.
This study aims to explore the feasibility of bladder-sparing treatment for large-volume
NMIBC, balancing quality of life with oncological outcomes.