Giving people with bladder cancer fewer but larger doses of radiation reduces the risk of their disease returning and should be adopted as the new standard of care, a new study shows.

Patients who received a shorter course of radiotherapy for bladder cancer that had invaded the surrounding muscles had a significantly lower risk of their cancer coming back than patients on a longer course.

Delivering larger but fewer doses of radiotherapy, and a reduced overall dose of radiation, did not increase the risk of side effects compared with those who received larger numbers of lower doses over a longer period.

The results could mean patients needing 12 fewer trips to hospital, without reducing the quality and impact of their bladder cancer treatment.

Researchers at The Institute of Cancer Research, London, and the University of Manchester analysed data from two previous clinical trials using advanced statistical methods to compare the two different radiotherapy schedules.

The study is the first to directly compare the two radiotherapy schedules that are currently used to treat muscle-invasive bladder cancer. It is published today in The Lancet Oncology, and the trials were funded by Cancer Research UK.

The researchers, who also included consultants who specialise in radiotherapy-related research at The Christie NHS Foundation Trust and The Royal Marsden NHS Foundation Trust, said their findings supported a change in standard of care for muscle-invasive bladder cancer – and stressed the particular benefits and relevance during the Covid-19 pandemic.

The study found that patients who received a 20-dose radiotherapy course delivered over four weeks had a 29 per cent lower risk of their cancer returning, over the five years following treatment, than those receiving a 32-dose course delivered over six and a half weeks.

The reduced risk of disease returning was observed whether patients received a combination of radiotherapy and chemotherapy, or radiotherapy alone.

Patients on the shorter course received a total of only 55 Gy of radiation, compared with 64 Gy on the longer one.

The study found no increased risk of side effects with the shorter course, and no significant difference in quality of life and overall survival between patients receiving the two radiotherapy schedules – concluding that the shorter course produces a similar outcome while using fewer resources.

Minimising hospital visits for cancer patients reduces their risk of exposure to Covid-19, and is more convenient for patients, while reducing demand on the NHS.

The two trials were the largest national phase III randomised clinical trials in patients with muscle-invasive bladder cancer treated with radiotherapy. The trials recruited similar patient populations, and the decision to use either radiotherapy schedule was taken by participating centres according to local standard practice.

Study co-leader Dr Nuria Porta, Principal Statistician at The Institute of Cancer Research, London, said:

“This study presented a unique opportunity to use data from two large randomised clinical trials to make comparisons between the two different radiotherapy schedules used to treat muscle invasive bladder cancer in the UK.

“Using robust statistical methods, we showed that the shorter course of radiotherapy was at least as good for patients overall and reduced the likelihood of a person’s cancer coming back after treatment.

“Not only is the shorter course more convenient for patients, but it also helps keep people out of hospital for their own good and to free up NHS resources, which is a vital consideration during the current pandemic.”