The impact of anaesthesia modality on oncological outcomes in patients with high-risk non-muscle invasive bladder cancer (NMIBC) remains uncertain. Emerging evidence suggests that anaesthetic agents and techniques may influence tumour biology and recurrence through immunomodulatory and neuroendocrine pathways. However, prospective randomised trials comparing spinal and general anaesthesia in this population are lacking.

This single-centre, prospective, parallel-arm randomised controlled trial will enrol 370 patients with clinically suspected high-risk NMIBC undergoing transurethral resection of bladder tumour. Participants will be randomised 1:1 to receive either spinal or general anaesthesia. The primary endpoint is time to recurrence over a 104-week follow-up period. Secondary endpoints include time to progression, Bacillus Calmette–Guérin (BCG) unresponsiveness and a composite oncological event. Additional secondary outcomes include postoperative opioid consumption (morphine equivalents), obturator jerk occurrence, acute urinary retention and tolerance to immediate intravesical chemotherapy. Safety outcomes will include treatment-emergent adverse events, Clavien-Dindo graded surgical complications, haemorrhagic events and anaesthesia-related risks. Exploratory endpoints involve perioperative biomarker analyses. Data will be analysed on an intention-to-treat basis.

Recruitment has not yet started. It is expected to begin in December 2025 and to be completed by June 2029. The planned follow-up period for each participant is 104 weeks. This manuscript is based on protocol V.1.0, dated March 2025. Results will be disseminated through peer-reviewed journals and conference presentations

NCT06982690.