Radiation therapy may be unnecessary for many breast cancer patients after mastectomy.

A study has shown that radiotherapy can be safely omitted from the treatment of many breast cancer patients who have undergone mastectomy and are taking anticancer drugs.

The 10-year survival rate of early-stage breast cancer patients who underwent mastectomy (mastectomy) was found to be similar regardless of whether or not they received radiation treatment.

Experts say the findings will help guide treatment discussions because many patients who currently qualify for radiation therapy after mastectomy under existing guidelines may not actually need radiation therapy.

For many early-stage breast cancer patients who have undergone mastectomy and chemotherapy, chest wall radiation therapy has long been the standard to kill any remaining cancer cells and lower the risk of recurrence.

This practice is based on trials from the 1980s that are now considered outdated, so uncertainty remains about its benefits and its use varies around the world.

The SUPREMO trial (Selective Use of Postoperative Radiotherapy after Mastectomy), led by the University of Edinburgh, studied the impact of chest wall radiotherapy in patients at intermediate risk of breast cancer recurrence.

The group included women from 17 countries with one to three affected lymph nodes, as well as women with other tumor characteristics of aggressive behavior that increase the likelihood of recurrence.

All 1,607 patients in the study underwent mastectomy, axillary surgery (removal of lymph nodes from the armpit) and modern chemotherapy. They were randomly assigned to receive chest wall radiotherapy (808 women) or no radiotherapy (799 women).

There was no difference in overall survival of patients after 10 years of follow-up. 81.4% of patients who received radiation therapy were still alive, compared with 81.9% of patients who did not.

Studies have also shown that radiation therapy has no effect on disease-free survival, the period of time during which cancer does not return, or on the spread of cancer from the breast throughout the body.

Radiation therapy had minimal effect on cancer recurrence at the mastectomy site. Nine patients who received treatment had breast cancer recurrence in the chest wall, compared with 20 patients who did not. Adverse effects from radiotherapy were mild and no excess deaths from cardiac causes were reported.

Experts believe radiation therapy has fewer benefits than previously thought. We believe this is due to gradual improvements in treatment, especially better medications that continue to reduce the likelihood of cancer recurrence and increase survival rates.

The research team was careful to note that the study only included patients with intermediate-risk breast cancer. Patients at higher risk of their cancer returning may benefit from chest wall radiotherapy, they added.

This study New England Journal of Medicine: (The URL will become active once the embargo is lifted). The international research team included scientists from the UK, Netherlands, Australia and China.

This study was funded by the Medical Research Council (MRC) and National Institute for Health Research (NIHR) Partnership, EORTC, Netherlands Cancer Society, Cancer Australia, Breast Cancer Research Institute, Edinburgh Cancer Center and HSBC Trustees. The study was jointly funded by the University of Edinburgh, NHS Lothian and Public Health Scotland.

Professor Ian Kunkler, from the Institute of Genetic Cancer at the University of Edinburgh, said: “The SUPREMO trial does not provide evidence to support the continued use of radiotherapy to the chest wall region in most patients with intermediate-grade breast cancer who have had a mastectomy and are receiving modern chemotherapy.”

“Although the toxicities reported in the clinical trials were mild, we know that almost all patients experience some side effects of radiotherapy, which can even occur years after treatment. Avoiding unnecessary irradiation can reduce the treatment burden and, for example, reduce the detrimental effects on breast reconstruction in mastectomy patients,” said Dr. Nicola Russell, study coordinator and Netherlands Cancer Institute on behalf of EORTC.

It is fantastic that this long-term, UK-led international trial has provided the high quality evidence that has been lacking in this important clinical area. The findings could potentially help patients avoid unnecessary treatment, leading to more effective and efficient use of health care and healthcare resources.

“This trial highlights how difficult but very important clinical questions can be answered through broad collaboration across the research community and a publicly funded partnership between the MRC and NIHR.”

Professor John Simpson, Director of the MRC-NIHR Efficacy and Mechanistic Evaluation (EME) Programme.