Age ≥ 18 years and able to understand participant information and give informed consent
Histologically verified urothelial bladder tumor
Unfit for cystectomy and/or radiotherapy
Patients with recurrence after radiotherapy unfit for salvage cystectomy
Disease where other treatments are considered unsuitable or have been declined by the patient
The patient may receive simultaneous systemic treatment
Selected high-burden non-muscle-invasive bladder tumors after MDT assessment
Eastern Cooperative Oncology Group (ECOG) Performance Status (PS) ≤ 2
Life expectancy of ≥ 3 months
Patients must be deemed able to tolerate general anesthesia
Sexually active participants in the reproductive age must use contraception. Accepted contraception includes the use of intrauterine device (IUD), oral contraceptives, male or female condom, vasectomy or female sterilization
Patients must stop treatment with anticoagulants before surgery in accordance with national guidelines
Plasma ionized Ca2+ must be within the normal upper limit. Correction is allowed
Hematology
* Thrombocytes ≥ 50 billion/L
* International normalized ratio (INR) ≤ 1.5. Correction is allowed
You may not be if
Pregnancy (confirmed by a blood sample) or lactation
Allergy to calcium gluconate or any of its excipients
Any clinical condition or previous treatment, that in the investigators' opinion made the patient ineligible
Contraindications to treatment with calcium gluconate as described:
* Hypersensitivity to calcium gluconate or any of its excipients
* Hypercalcemia (e.g. due to hyperparathyroidism, hypervitaminosis D, decalcifying malignancies, renal insufficiency, immobilization osteoporosis, sarcoidosis, milk-alkali syndrome)
