Women With Early-Stage Breast Cancer May Safely Skip Radiotherapy After Mastectomy: Study

Women with early-stage breast cancer who undergo mastectomy (breast removal) and receive modern anti-cancer drug therapy may not need radiotherapy, according to a major international study that found no difference in long-term survival between those who received the treatment and those who did not.

The findings, published in the New England Journal of Medicine, come from the SUPREMO trial (Selective Use of Postoperative Radiotherapy after Mastectomy), led by the University of Edinburgh and funded by the Medical Research Council (MRC) and National Institute for Health and Care Research (NIHR).

The trial involved 1,607 women from 17 countries who had early-stage breast cancer and were at intermediate risk of recurrence. All participants underwent mastectomy, axillary surgery (removal of lymph nodes from the armpit), and received modern systemic therapy. They were randomly assigned to receive either radiotherapy (808 patients) or no radiotherapy (799).

After ten years of follow-up, the study found no significant difference in overall survival between the two groups. Survival stood at 81.4% among those who received radiotherapy, compared with 81.9% among those who did not.

Radiotherapy also showed no impact on disease-free survival—the length of time patients lived without the cancer returning—or on the risk of cancer spreading elsewhere in the body. Only nine women in the radiotherapy group experienced a local recurrence on the chest wall, compared with 20 in the non-radiotherapy group.

Experts said the results could influence treatment guidelines worldwide, potentially sparing many women from unnecessary radiotherapy and its side effects. “The SUPREMO trial provides no evidence to support the continued use of chest wall radiotherapy in most patients with intermediate-risk breast cancer who have undergone mastectomy and are treated with modern systemic therapy,” said Professor Ian Kunkler, from the University of Edinburgh’s Institute of Genetics and Cancer, who led the trial.

The study found that radiotherapy side effects were generally mild, with no excess deaths from heart-related causes. Researchers noted that advances in drug therapies have significantly reduced recurrence risk, further diminishing the need for routine post-mastectomy radiotherapy.

However, the authors cautioned that the findings apply only to intermediate-risk patients. Those at higher risk of recurrence might still benefit from radiotherapy, they said.

Professor John Simpson, Director of the MRC-NIHR Efficacy and Mechanism Evaluation Programme, said the study underscored the value of international collaboration in addressing key clinical uncertainties. “The findings potentially allow patients to avoid unnecessary treatments, leading to more effective and efficient use of health and care resources,” he said.

The research team included scientists from the UK, Netherlands, Australia, and China, with additional support from the European Organisation for Research and Treatment of Cancer (EORTC), the Dutch Cancer Society, Cancer Australia, the Breast Cancer Institute, and the Edinburgh Cancer Centre.