Targeting or reducing the dose of radiotherapy for women with breast cancer after surgery can substantially reduce the side effects they experience, a large-scale clinical trial has shown.

The trial also found some women were more likely to experience side-effects than others – for example, women were more likely to report side effects if they were younger, had larger breasts or if they were feeling anxious or depressed before beginning treatment.

Spotting women more likely to experience side effects will help doctors to personalise a patient’s treatment – offering women at higher risk additional support, monitoring or alternative treatment options.

The study – led by researchers at The Institute of Cancer Research, London, and the University of Cambridge, and involving 71 centres across the UK – has already begun to change clinical practice after reporting earlier this year that the modified radiotherapy regimes were as effective as a high dose to the whole breast.

Now the researchers have shown women with breast cancer experienced fewer long-term side effects if treated with radiotherapy to part of the breast or at a reduced dose than with high-dose radiation to the whole breast over the five years of the study.

There were also major declines in side effects in all the treatment groups over the course of the study, with over half of women having no side-effects at all five years after treatment.

The study is published in the Journal of Clinical Oncology and was funded by Cancer Research UK.

Researchers randomly assigned 2018 women to three different radiotherapy regimes after surgery: a standard radiation dose of 40 Gy to only the part of the breast that contained the original tumour; a reduced dose of 36 Gy to the whole breast or standard treatment with 40 Gy to the whole breast.

The researchers used a type of radiotherapy that is ‘intensity modulated’ – a technique pioneered by The Institute of Cancer Research (ICR) and The Royal Marsden NHS Foundation Trust which precisely shapes the beam to the tumour.

The researchers asked patients to report back on their experiences five years after having breast radiotherapy using questionnaires.

Some 1,265 patients taking part in the IMPORT LOW trial filled in questionnaires before they were assigned to one of the groups of the trial, and then six months, and one, two and five years after receiving treatment.

Radiotherapy to part of the breast was associated with a 23 per cent reduction in the number of adverse events women experienced over the course of the study, compared with a high dose to the whole breast.

The reduced-dose radiotherapy was associated with a 17 per cent reduction in adverse events.

Reports of breast hardness, pain, oversensitivity, swelling, skin changes and arm or shoulder pain all reduced during the study, and after five years 58 per cent of women had no side effects at all.

Study co-leader Professor Judith Bliss, Director of the Clinical Trials and Statistics Unit at The Institute of Cancer Research, London, said, “Improving cancer treatment isn’t only about extending life but also about making sure that people who survive cancer can live as well as possible. Our trial has shown that it is possible to safely dial back treatment so that women who have surgery for breast cancer not only have excellent survival but also the best quality of life possible.”

“We are delighted that the results of this trial are now leading to a real change in the way breast cancer patients are treated and hope it has a real benefit for their recovery. The technique used here can be carried out on standard radiotherapy machines so these results can be achieved at centres across the country and worldwide.”

Dr Indrani Bhattacharya, a Clinical Research Fellow at The Institute of Cancer Research, London, and first author on the study, said, “We hope the results can provide reassurance for women considering radiotherapy after surgery that they will get the kindest possible treatment regime. The results are already changing clinical practice, and will also help doctors identify patients who are at higher risk of experiencing side effects, prepare their patients for what they might experience and put in place a more personalised programme of treatment for them.”

Study co-leader Dr Charlotte Coles, Consultant Clinical Oncologist, University of Cambridge and Cambridge University Hospitals NHS Foundation Trust, said, “We’re really pleased we have demonstrated a very effective radiotherapy approach that also reduces the side effects of treatment. Minimising these long-term side effects is essential, as not only do they impact on physical health, but they can also cause psychological distress.”

Professor John Yarnold, Professor of Clinical Oncology at The Institute of Cancer Research, London, and Consultant Clinical Oncologist at The Royal Marsden NHS Foundation Trust, who led the trial between 2008 and 2013, said, “When we first started the IMPORT LOW trial, evidence was beginning to emerge that suggested if a person’s cancer returned it tended to grow back close to the site of the original tumour.

“We set up the trial to test whether women with breast cancer could be spared unnecessary radiation to the whole breast or given less radiation to reduce the side effects they experience from treatment, while still successfully getting rid of the tumour.

“Patient self-assessments of treatment outcome have played a hugely important part in this endeavour, which is now changing standard of care for about half of all UK women with early breast cancer.”

Professor Arnie Purushotham, Cancer Research UK’s Senior Clinical Adviser, said, “One of the challenges of treating early stage breast cancer is trying to minimise the side effects, which can have a real impact on a woman’s life, without affecting the chances of curing her. The progress we’ve made treating breast cancer has been phenomenal, and Cancer Research UK’s funding for trials like this, helps develop kinder treatments and improve quality of life for women.”

Hilary Stobart, a patient on the IMPORT LOW trial, said, “After having a discussion with a research nurse and reading the trial information, I decided to take part in IMPORT LOW because I felt it was very important to find out whether partial radiotherapy was as effective for patients as it would hopefully have fewer side effects than whole breast radiotherapy.

“I was also very pleased that I could report my own view of my symptoms and side effects to be included in the final results.  I hoped that I might benefit myself from taking part, but realised that even if I had the standard treatment I would still be able to contribute. I am now very proud to see that outcomes from the trial have been published and that these are already changing practice for the better for new patients."

Source: The Institute of Cancer Research