Adaptive Radiotherapy for Carcinoma of the Urinary Bladder: Long-term Outcomes With Dose Escalation - Beyond the Abstract

Invasive bladder cancer has traditionally been treated with radical cystectomy, which is a significantly morbid surgery. Radiotherapy (RT) has been the cornerstone of trimodality therapy as an alternative to avoid surgery and preserve the bladder.

Over the years, radiation oncologists have struggled to treat these patients optimally with conventional techniques due to dose-limiting pelvic toxicity associated with large portals required for adequate coverage of a moving target. Even with IMRT, the debate regarding adequate margins and the risk of geographical miss of this mobile organ has continued. Adaptive radiotherapy has emerged as a feasible solution by incorporating image guidance to ensure accurate dose delivery.

‘Plan of the day’ technique of adaptive RT utilizes a patient-specific library of plans to choose a best-fit plan for the bladder as seen in daily on-board imaging. While many small studies have reported good results with this technique, this study is the first one to show that these results are also achievable in daily clinical practice outside of the controlled setting of clinical trials. We have been able to preserve the bladder in >80% patients, and the survival outcomes are comparable to the modern cystectomy studies. Also, small margins have been shown to be adequate for bladder coverage with the use of daily image guidance. It has also allowed us to escalate the total bladder radiotherapy dose safely. Though dose escalation was feasible and did not impart additional toxicity, it was not observed to improve clinical outcomes. Further research is required to establish any benefit with higher bladder dose, and the potential of systemic therapy combined with radiotherapy to improve survival. However, bladder preservation with radical chemoradiation using ‘plan of the day’ adaptive RT is certainly a valid alternative for patients desirous of avoiding a cystectomy.

Written by: Vedang Murthy, MD, DNB, DipEPP, and Priyamvada Maitre, MD, Department of Radiation Oncology, Homi Bhabha Cancer Hospital, Tata Memorial Centre, Mumbai, India

Read the Abstract