According to a trial carried out on 1,600 people, the benefits are more limited than one might think.
Around 60,000 new cases of breast cancer are recorded each year in France. For some women, mastectomy, or the removal of the breast, is necessary to treat the disease. This intervention can also be used as prevention in women at high risk of breast cancer, such as those carrying the BRCA gene. According to figures published in 2025, 20,000 to 22,000 women each year undergo a total mastectomy (complete removal of the breast) as part of the treatment of breast cancer.
Traditionally, doctors offer radiotherapy (or “radiation”) after mastectomy to reduce the risk of local recurrence, especially in patients with factors associated with a higher risk of recurrence, such as a large tumor or lymph node involvement. On the other hand, its benefit in women suffering from so-called “intermediate risk” breast cancer for recurrence has until now remained less clearly established. The SUPREMO trial, carried out in the United Kingdom, brings new elements to the debate. This randomized study included nearly 1,600 patients who had undergone a mastectomy, followed for a median duration of 10 years.
The results show that, in this intermediate-risk population, the addition of radiotherapy after surgery does not result in a significant improvement in overall survival, nor in metastasis-free survival, compared to no radiotherapy.
On the other hand, radiotherapy does reduce the risk of local recurrence, with a relative reduction estimated at around 45%. However, experts emphasize that the real difference observed between the two groups remains limited, with a gap of around 2 points between treated patients and those who were not. A benefit considered “modest” in view of the potential adverse effects of radiotherapy, particularly cutaneous, cardiac or pulmonary, as well as its impact on quality of life.
These results do not lead, at this stage, to a questioning of the current recommendations. Several limitations are mentioned, notably the evolution of surgical practices, systemic treatments and screening since the start of the trial. They are nevertheless part of a broader reflection in oncology, that of therapeutic de-escalation, which aims to adapt the intensity of treatments to the real level of risk.
In practice, radiotherapy after mastectomy remains indicated in patients at high risk of recurrence. But these new data could, ultimately, encourage more detailed individualization of decisions, based on the tumor profile, biological characteristics and patient preferences.
