Scans on day of treatment could improve bladder radiotherapy

02 January 2015

Using scan to tailor radiotherapy more accurately to each patient could lead to fewer needing their bladder removed. 

Scientists from The Institute of Cancer Research and The Royal Marsden gave 25 bladder cancer patients a scan on the same day of treatment to tailor radiotherapy more accurately to each patient. The new technique reduced the average amount of healthy bowel exposed to radiation by 40%, while more effectively covering the tumour, compared to standard bladder radiotherapy.

Reducing bowel toxicity rates could mean bladder radiotherapy is more suitable for more patients, which could lead to fewer needing their bladder removed.

Published in the journal Clinical Oncology, the study was funded by the NIHR Biomedical Research Centre at The Institute of Cancer Research (ICR) and The Royal Marsden, and Cancer Research UK, with additional funding from the Francis Wain Jewellers Charitable Trust.

One of the difficulties of treating bladder cancer with radiotherapy is that the bladder expands and contracts throughout the course of a normal day. Doctors scan a patient’s bladder a few days ahead of treatment to create a radiotherapy treatment plan. To account for these changes a large safety margin is traditionally used, which means often they irradiate larger areas than required. Despite this large margin for error, the changing size of the bladder, along with the natural movement of organs in the body, can still leave parts of the tumour un-treated, while also irradiating unaffected organs.

But the new way of treating patients, called adaptive bladder radiotherapy, uses multiple treatment plans and a scan on the day of treatment to tailor the radiotherapy to more accurately target the tumour and avoid healthy tissue.

Immediately before radiotherapy treatment, clinicians scanned the patients’ bladders and used this to build the Plan of the Day (PoD) treatment from three treatments plans covering increasing volumes of the bladder. The amount of radiation each patient was exposed to was recorded and compared against the exposure they would have received following the standard treatment plan.

Under the new technique patients received treatment that exposed less healthy tissue to radiation compared with the dose they would have received under standard care. On average, the PoD treatment reduced the amount of healthy bowel exposed to a high dose of radiation by 219cm3, or 40%, compared to standard radiotherapy.

Dr Robert Huddart, Clinical Consultant in Radiotherapy at The Institute of Cancer Research, London, said: “Our study showed that scanning patients on the day of treatment to tailor bladder radiotherapy was more accurate than current treatment.

“In bladder cancer, the amount of radiation used is limited to prevent harmful exposure of the bowel, but our new adaptive bladder radiotherapy technique spared an additional 40% of healthy bowel compared to standard radiotherapy, so it could be of real clinical benefit to patients.  

“A new phase II clinical trial called HYBRID will see if this treatment strategy can show the same benefits in a larger number of patients. If successful, adaptive bladder radiotherapy could be rolled out nationwide within a few years.”