Image-guided radiotherapy for muscle invasive bladder cancer with intravesical lipiodol injection A new option for bladder sparing treatment

Introduction and aim: To implement lipiodol as a fiducial marker of the tumor bed for image-guided radiotherapy with simultaneous integrated boost technique as part of radiochemotherapy for muscle invasive bladder tumors. Method: Since April 2016, radiochemotherapy was performed in 3 male patients with muscle invasive, transitional cell bladder carcinoma. Prior to radiochemotherapy, tumor bed resection was performed for each patient, at the same time 10 ml of lipiodol solution was injected submucosally into the resection site, thus marking the tumor bed for escalated dose irradiation. During radiochemotherapy 51 Gy (1.7 Gy/die) to the pelvis, 57 Gy (1.9 Gy/die) to the whole bladder, and 63 Gy (2.1 Gy/die) to the lipiodol-labeled tumor bed was delivered with simultaneous integrated boost technique. The accuracy of the irradiation was controlled by daily kilovoltage CT. Early radiogenic urogenital and gastrointestinal side effects were recorded according to Radiation Therapy Oncology Group side-effects grading recommendation. Results: Substantial perioperative side effect or toxicity were not observed during and after the injection of lipiodol. The prescribed dose was successfully delivered in all patients. Radiotherapy duration was 6 weeks. The lipiodol-labeled tumor bed was clearly visible on daily kilovoltage cone beam CT. In one patient grade II cystitis and proctitis was observed, another patient experienced only grade I cystitis. These complaints improved with symptomatic medication. In the third patient no significant side effect occurred. Conclusions: The injection of lipiodol into the bladder wall is a safe technique, without any perioperative toxicity or complication. The tumor bed demarcated by lipiodol was visible both on treatment planning and kilovoltage CTs. The total treatment time was shortened by 4 days. The treatment was well tolerated, early side effects were moderate, or slight.