Whole Brain Radiotherapy Versus Stereotactic Radiosurgery in Breast Cancer Patients With Brain Metastases-A Phase 3 Open Label Randomized Study.

[BACKGROUND] Patients with brain metastases can be treated with whole-brain radiotherapy (WBRT) or stereotactic radiosurgery (SRS). There are no randomized study comparing WBRT with SRS in patients with brain metastases from breast cancer. This study aimed to compare WBRT with SRS in patients with breast cancer with brain metastases.

[MATERIAL AND METHODS] Breast cancer patients with 1-5 brain metastases, ≤ 3.5 cm and KPS ≥ 60 were randomized to WBRT or SRS. WBRT dose was 30 Gy/10 fractions /2 weeks. SRS dose varied from 18 to 24 Gy per fraction to 27-36 Gy in 3-6 fractions. Primary endpoint was overall survival (OS) and the secondary end points were progression free survival (PFS), performance and neurologic status, and cognitive impairment. The trial was approved by the institute ethics committee and registered in clinicaltrials.gov NCT05144867.

[RESULTS] Between July 2021 and January 2023, 103 patients were randomized; 51 in the WBRT arm and 52 in the SRS arm. Mean tumor diameter was 3.40 ± 1.22 and 2.81 ± 1.24 cm in WBRT and SRS, respectively. The median follow-up duration was 17.5 months (IQR- 7-21.9 months). Local recurrences were observed in five (9%) and nine (17%) patients in the WBRT and SRS (p = 0.32) group, respectively. Distant intracranial relapse occurred in 11 (21%) and 20 (39%) patients treated with WBRT and SRS (p = 0.36), respectively. Median OS was 17.4 months (95% CI: 6.63-17.8 months) in the WBRT arm and 14.6 months (95% CI: 14-15.2 months) in the SRS arm (p = 0.817). Median PFS was 13.9 and 11.0 months, respectively, for WBRT and SRS (p = 0.73). The 1-year OS and PFS were 55% and 47% (p = 0.51) and 41% and 43% (p = 0.75) with WBRT and SRS, respectively. At 3 months, patients treated with WBRT showed significantly better improvement in KPS (p = 0.004). In both the arms the MMSE improved at 3 months from the baseline, but it was greater with SRS.

[CONCLUSION] There was no significant difference in the outcomes between the SRS and WBRT in breast cancer patients with brain metastasis. WBRT led to a significant improvement in the KPS. Cognitive decline was lower in the SRS arm.