Adjuvant radiotherapy in postmenopausal women with early-stage ER-positive breast cancer: A systematic review and meta-analysis.

Background: The management of early breast cancer (BC) includes breast-conserving surgery (BCS), postoperative radiation therapy (PORT) and systemic therapy. Therefore, we aim at evaluating all the efficacy endpoints for PORT compared to no PORT in older women with early-stage BC.

Method: We searched PubMed, Web of Science, Cochrane, and Scopus databases from inception up to May 2024 for randomized controlled trials (RCTs) where patients were randomized into either PORT vs no PORT. The following outcomes were studied: any local recurrence, nodal recurrence, contralateral BC, distant relapse, all-causes and cancer-specific mortality.

Result: Seven eligible RCTs with a total of 4860 patients were included; 2435 of them received PORT; and 2425 did not. All patients had a node-negative disease, with 84.4% older than 60 years and only 10.4% had tumors larger than 2 cm. Patients in both treatment arms were offered adjuvant endocrine therapy e.g. tamoxifen and anastrozole. The median follow-up was 9.7 years (95% CI: 5.1-11.3). The survival risk for any local recurrence for patients with no radiotherapy was significantly higher than for those who used PORT (HR: 6.3; 95% CI: 4.17-9.52). Also, patients in the PORT arm had a significantly lower risk of nodal recurrence (risk of recurrence (RR): 0.28, 95% CI: 0.11-0.72, P = .009). However, PORT was not associated with a significant reduction in the risk of contralateral BC, distant relapse, BC-specific mortality or all-cause mortality (RR: 0.883, 1.52, 1.12, 0.995, respectively).

Conclusion: Postoperative radiotherapy significantly reduces local and regional recurrence following BCS in early estrogen receptor-positive elderly BC with limited value on distant recurrence or mortality. The risk-benefit ratio should be determined for every patient to avoid overtreatment of a significant proportion of patients.