Radiotherapy boost cuts treatment time for breast cancer patients by at least a week

Professor Charlotte Coles
Treatment times for radiotherapy could be reduced for some early breast cancer patients, according to a trial led by Professor Charlotte Coles and funded by Cancer Research UK.

Results from the IMPORT HIGH trial, published in The Lancet, show that giving some breast cancer patients a targeted additional dose of radiotherapy at the same time as treatment to the whole breast (known as simultaneous integrated boost or SIB) cuts the time taken to complete treatment by at least one week.

The trial, led by University of Cambridge and The Institute of Cancer Research, London, found that SIB radiotherapy given at the right dose works just as well as existing radiotherapy techniques in reducing the risk of the cancer returning in the treated breast.

The chance of the cancer returning to the treated breast remained very low after 5 years across all treatment groups. Patients given the lower dose of SIB radiotherapy reported similar rates of side-effects, like breast hardening or firmness, as those who received the standard sequential radiotherapy schedule.

Currently, women with a higher than average risk of cancer coming back in their treated breast are given an additional radiotherapy dose to the original site of the tumour after radiotherapy is given to the entire breast. This approach, known as sequential boost, maximises the chances that any remaining cancer cells are removed from the breast.

But it takes longer for women to complete sequential boost radiotherapy, requiring them to attend more hospital appointments. In the UK, many women requiring breast boost radiotherapy are given 4 weeks of radiotherapy – 3 weeks to the whole breast with 1 week boost afterwards. In some countries, women are given 6.5 weeks of radiotherapy – 5 weeks of whole breast radiotherapy with 1-1.5 weeks boost afterwards. SIB radiotherapy cuts this down to just 3 weeks in total.

A boost treatment also increases the chance of having potentially long term side-effects after treatment, including changes in shape, size and texture of the breast that can affect women’s self-esteem and wellbeing.

In the trial, patients were divided into three groups. The first group received whole breast radiotherapy with a sequential boost over 4.5 weeks in total. The second and third groups each received two different doses of SIB radiotherapy. Patients received whole breast radiotherapy with a simultaneous boost of either lower or higher dose a dose over 3 weeks in total. There was no advantage shown for those who received the higher boost dose it also led to slightly increased rates of side effects.  

Researchers hope that SIB radiotherapy could reduce the costs for patients travelling to hospital and cut the time taken to undergo treatment and recovery. It could be quickly adopted by the NHS and health systems worldwide as standard radiotherapy equipment is used, freeing up valuable appointment visits that could be used to treat more cancer patients sooner.

In total, 2,617 patients at 76 centres took part in the trial.

Mum of two Helen Lee (46), from Mepal near Cambridge, was amongst them.

In October 2013, she first noticed an unusual twinge in her right breast and had a hunch that something wasn’t right. Her GP couldn’t feel anything when she examined Helen but referred her to the Breast Unit at Addenbrooke’s Hospital for a mammogram to reassure her.

But, at the young age of 36, Helen was diagnosed with breast cancer. The mammogram revealed a tumour just over 2cm in size located deep in her breast tissue. She remembered:

“I felt quite relieved because I knew there was something wrong. And my surgeon said it was so deep I wouldn't have felt it. So I was actually really lucky otherwise I would have come in at 51 for screening and it might not have been treatable by then.”

Helen had surgery a few weeks after her diagnosis, followed by a course of chemotherapy. When she was due to begin radiotherapy treatment she was asked if she would like to take part in the IMPORT HIGH trial. Helen was assigned to a group receiving a targeted radiotherapy boost delivered simultaneously during her whole breast radiotherapy treatment, which reduced her treatment from 23 sessions over 4.5 weeks to 15 sessions over 3 weeks.

“I was happy to sign up for the IMPORT HIGH trial because they explained that it was how they'd like to do radiotherapy in the future.

“I got the shorter treatment schedule and I went in for fewer appointments. It was good for me as I'm about 40 minutes from Addenbrooke’s, it is quite a journey there and back.

“I feel like I've had a more supported journey through my treatment from having been on a trial, because I've had 10 years of follow-up appointments. It makes a huge, huge difference to speak to people who can help me with things that other people wouldn't understand.”

After undergoing surgery, chemotherapy and radiotherapy treatment, Helen has now been clear of cancer for nearly 10 years.

Since her diagnosis and treatment, she has taken part regularly in Cancer Research UK Race for Life, Pretty Muddy and Shine Night Walk events in Cambridge, Bedford and Stamford, fundraising for life-saving research into future treatments for cancer patients.

Reflecting on her cancer journey, Helen said: “One thing that really struck me, at one of the first Cambridge Race for Life events that I did after my diagnosis, was watching the screen on Parker's Piece where they're playing the films where the scientists are talking about what they've been working on.

“I felt so overwhelmed that all of the people there that day were part of saving my life, and that all the people who took part in trials 10 years ago, 15 years ago, 20 years ago, everything they've done meant that I survived my cancer.”

Professor of Breast Cancer Clinical Oncology at Cambridge University, National Institute of Health Research and Care Research (NIHR) Professor, CRUK RadNet Cambridge lead and chief investigator for the trial, Professor Charlotte Coles, said:

“Some women have to live with permanent breast changes after radiotherapy which may affect their well-being. With SIB, we can deliver high-quality effective radiotherapy whilst minimising toxicity from it.

“This is a careful step towards even shorter courses of radiotherapy that include more complex techniques. By delivering more targeted boost radiotherapy over shorter time periods, women can get on with their lives more quickly”.

The National institute of Health and Care Research (NIHR)-funded FAST Forward trial, which was also led by the ICR-CTSU and reported results in 2020, showed that whole breast radiotherapy could be given over a week. Researchers are now hoping to run another clinical trial to find out if SIB radiotherapy can be delivered to patients requiring a boost in just one week.

Professor Judith Bliss, Professor of Clinical Trials at The Institute of Cancer Research, London,  Director of the Cancer Research UK-funded Clinical Trials and Statistics Unit at the ICR which is managing the IMPORT HIGH trial, said:

“For some patients who have a higher risk of seeing their cancer return in the treated breast, delivering an extra, targeted boost of radiotherapy to breast tissue close to the original tumour site is an effective way to lower that risk and help keep cancer from returning to the breast.

"IMPORT HIGH has uncovered how we can streamline our delivery of these radiotherapy boosts - giving them simultaneously with whole breast radiotherapy - without impacting the effectiveness of treatment, or causing patients additional side effects.  We hope this trial will change clinical practice - allowing women to benefit from sophisticated radiotherapy delivery with shorter treatment times and fewer hospital visits."

Chief Executive of Cancer Research UK, Michelle Mitchell, said: 

“At a time when health services across the UK are facing chronic staff shortages in cancer services, we need to look at new ways to get more patients treated as quickly as possible. In addition to training up more staff, more precise forms of radiotherapy can help to reduce the number of people who are waiting too long to begin vital treatment.

“Trials like IMPORT HIGH are leading the way in delivering smarter radiotherapy with existing technology. We hope that treatment centres across the UK and globally will rapidly adopt this approach to beat breast cancer sooner and give patients more precious time with their loved ones.”

Additional funding for research arising from the IMPORT HIGH trial is provided by the NIHR.

Prof Charlotte E Coles et al Dose-escalated simultaneous integrated boost radiotherapy in early breast cancer (IMPORT HIGH): a multicentre, phase 3, non-inferiority, open-label, randomised controlled trial The Lancet June 08 2023 DOI:

3 Jul 2023