PATIENTS with intermediate-risk breast cancer demonstrate comparable 10-year overall survival rates, irrespective of chest wall irradiation (CWI) following mastectomy, as shown in findings from the BIG 2-04 MRC SUPREMO trial.
The study, presented at the San Antonio Breast Cancer Symposium 2024, sought to resolve ongoing debate about the necessity of CWI in patients with intermediate-risk breast cancer, which includes individuals with 1-3 positive lymph nodes or node-negative disease but high-risk tumor features. Current guidelines suggest variable recommendations for these cases. The international phase III trial enrolled 1,607 patients meeting strict eligibility criteria and randomly assigned them to receive CWI or to omit it. Patients received comprehensive multidisciplinary care, including systemic therapy and axillary surgery.
After a median follow-up of 9.6 years, survival outcomes between the CWI and no-CWI groups were nearly identical, with 81.4% and 82.0% of patients alive, respectively. While CWI reduced chest wall recurrence rates by over half, this represented a minor absolute reduction of less than 2%, deemed clinically insignificant. Subgroup analysis confirmed no survival benefit for patients with either N0 or N1 disease. These findings suggest that omitting CWI is a safe option for most intermediate-risk patients.
The study has significant implications for clinical practice, enabling more personalized and less burdensome treatment plans. Given the negligible survival benefits and limited impact on recurrence rates, CWI can often be omitted in these patients, facilitating shared decision-making and improving quality of life by sparing patients the side effects and logistical challenges of radiotherapy. Future research could explore the specific patient subgroups where CWI might still provide benefits and the role of evolving systemic therapies in reducing recurrence risks.
While limitations such as low accrual for some patient categories were noted, the results remain robust for the majority of intermediate-risk patients treated in modern multidisciplinary care settings.
Reference
Kunkler I et al. Does postmastectomy radiotherapy in ‘intermediate-risk’ breast cancer impact overall survival? 10 year results of the BIG 2-04 MRC SUPREMO randomised trial: on behalf of the SUPREMO trial investigaton. Abstract GS2-03. SABCS, 10-13 December, 2024.
