Practice-changing clinical trial reduces long-term radiotherapy side effects in women with breast cancer

From: icr.ac.uk

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.

‘Intensity modulated’ radiotherapy

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.