Partial Bladder Boost Using Lipiodol Marking During Image-guided Radiotherapy for Bladder Cancer.

Background/Aim: Secure dose escalation is required to compensate avoidance of concurrent chemotherapy in radiotherapy for increasing elderly bladder cancer. We aimed to evaluate the efficacy of lipiodol submucosally injected as a fiducial marker during image-guided radiotherapy (Lip-IGRT) for muscle invasive bladder cancer (BC). Patients and Methods: Twenty-three patients with T2a-4aN0-1M0 BC underwent whole-bladder irradiation of 46 Gy and Lip-IGRT of 20 Gy, conventionally. The bladder volume exposed to 19 Gy (V-b(19):%) on Lip-IGRT was referred as an index predicting cystitis. Results: Lipiodol consistently highlighted the boundaries of 20 tumors (88%) on planning and portal verification images. Three of 4 patients under oral anticoagulant agents usage were complicated with grade >= 2 hematuria for 3 days (a patient with a bV19 of >50%) or more than a year (2 patients with bV19 of <50%) after the injection. The 3-year overall survival and disease-free survival rates were 70.4% and 71.1%, respectively. Conclusion: Lipiodol marking is an effective way of demarcating BC. However, it is necessary to address the comorbidities of elderly patients.