An international trial found that patients with early-stage breast cancer who underwent a mastectomy, removal of the breast, had similar 10-year survival rates whether or not they received radiotherapy.
The trial was funded by the Medical Research Council (MRC).
Guiding treatment discussions
Experts say the findings should help guide treatment discussions, as many patients who currently qualify for radiotherapy after mastectomy under existing guidelines may not actually need it.
For many patients with early-stage breast cancer treated by mastectomy and anti-cancer drugs, chest wall radiotherapy has long been standard to kill any remaining cancer cells and lower the risk of recurrence.
The practice is based on trials from the 1980s, now considered outdated, leaving uncertainty about its benefit and leading to variation in use worldwide.
The trial
The SUPREMO trial (Selective Use of Postoperative Radiotherapy after Mastectomy) was led by The University of Edinburgh.
It studied the impact of chest wall radiotherapy in patients at intermediate risk of breast cancer returning.
1,607 patients studied
The group included:
- women from 17 countries with one to three affected lymph nodes
- women with no affected lymph nodes, but who had other tumour features of aggressive behaviour that increase the chance of recurrence
All 1,607 patients in the study underwent:
- mastectomy
- axillary surgery, removing lymph nodes from the armpit
- modern anti-cancer therapy
Of these patients, 808 were randomly assigned to chest wall radiotherapy and 799 to no radiotherapy.
The findings
No difference in patient survival
There was no difference in overall survival of patients after 10 years of follow up.
81.4% of those who received radiotherapy were still alive, compared with 81.9% of those who did not.
No impact on disease-free survival
The study found that radiotherapy also had no impact on disease-free survival, the length of time without any cancer returning, or on the cancer spreading from the breast around the body.
Minimal impact on cancer returning
Radiotherapy had minimal impact on cancer recurring at the site of mastectomy.
Nine patients who received the treatment saw their breast cancer return on the chest wall, compared with 20 who did not.
Mild side effects
Side effects from radiotherapy were mild with no excess deaths reported from cardiac causes.
The outlook
Experts attribute radiotherapy providing less benefit than previously thought to progressive improvements in treatment, particularly better drug treatments, which continue to reduce the chances of the cancer returning, and boost survival rates.
The research team caution that the study only looked at those with intermediate-risk breast cancer.
They added that patients with a higher risk of their cancer returning could possibly benefit from chest wall radiotherapy.
Collaboration
Professor John Simpson, Director of the MRC National Institute for Health and Care Research (NIHR) Efficacy and Mechanism Evaluation Programme, said:
It is fantastic that this long-term international clinical trial, led from the UK, has delivered high-quality evidence that was lacking in this important clinical area.
The findings potentially allow patients to avoid unnecessary treatments, leading to more effective and efficient use of health and care resources.
The trial emphasises how difficult, but really important clinical questions can be answered by broad collaboration in the research community and through public funding partnerships such as that between MRC and NIHR.
Anti-cancer drug progress
Professor Ian Kunkler, from The University of Edinburgh’s Institute of Genetics and Cancer, said:
The SUPREMO trial provides no evidence to support the continued use of radiotherapy to the area of the chest wall in most patients with intermediate-risk breast cancer who have undergone a mastectomy if they are also treated with modern anti-cancer drug treatment.
Unnecessary treatments
Dr Nicola Russell, from the Netherlands Cancer Institute and study coordinator on behalf of the European Organisation for Research and Treatment of Cancer (EORTC), said:
Although reported toxicity in the trial was mild, we know that almost all patients experience some side effects of radiotherapy, that can even develop even some years after treatment.
Avoiding unnecessary irradiation will reduce both treatment burden and, for example, the detrimental effects on breast reconstruction for these mastectomy patients.
International team
The study, conducted by an international team of scientists from the UK, Netherlands, Australia and China, is published in the New England Journal of Medicine.
It was also funded by:
- the NIHR partnership
- EORTC
- Dutch Cancer Society
- Cancer Australia
- Breast Cancer Institute
- Edinburgh Cancer Centre
- HSBC Trustees