ESTRO 2024 - Abstract Book

S450

Clinical - Breast

ESTRO 2024

Results:

Between July 2021 to June 2023, total 105 patients with breast cancer with brain metastases were randomised, 54 in the SRS arm and 51 in the WBRT arm. Two patients were excluded in the WBRT arm as they received 8Gy/SF and 20Gy/5#, respectively. Mean tumor diameter was 3.55 ± 1.22, 2.49 cm ±0.9 cm and 3.56 ± 1.24 cm in WBRT, sSRS and fSRS, respectively. sSRS was delivered in 27(50%) and fSRS in 27(50%) patients. The median follow up was 17.5 months (IQR-7-21.9 months). Distant intracranial relapse occurred in 11(21%) and 20(39%) patients with WBRT and SRS (p=0.36), respectively. Distant progression occurred in 7(13%) and 12(24%) patients with WBRT and SRS (p=0.21), respectively. The Median PFS was 17.4 months (95% CI – 6.63-17.8 months) in the WBRT group and 14.6 months (95% CI – 14-15.2 months) in the SRS group (p=0.817). At 1-year OS was 55% and 47% with WBRT and SRS(p=0.51), respectively. At 1-year PFS was 41% and 43% with WBRT and SRS(p=0.75), respectively. A KPS score of 60 or less(p=0.019) and RPA class of 3 (p=0.04) had a significant adverse effect on the PFS. Five patients developed perilesional edema which manifested as nausea and vomiting in 4 patients and two patients also reported headache. These were managed conservatively. One patient in the SRS arm developed radionecrosis within the irradiated volume demonstrated on follow up MRI at 6 months. She was managed conservatively. No additional neurological deficit was reported. This patient had received trastuzumab concurrently with SRS. No treatment related deaths were noted. Systemic functional status at 6 months was evaluated in 45(88%) patients in the WBRT arm and 48(89%) in the SRS arm. It improved in in 43(83%) and 45(88%) patients with WBRT and SRS (p=0.58), respectively. Neurologic function improved in 41(79%) and 42(78%) patients with WBRT and SRS (p=0.80), respectively.

Conclusion:

There was no significant difference in survival outcomes with SRS and WBRT in breast cancer patients with brain metastasis. Poor performance status and RPA of class 3 were clinical predictors of worse survival. Systemic functional status and neurological function status was also comparable between the two groups.

Table 1. Relapse rate and toxicity with WBRT and SRS

All

WBRT

SRS

p

Characteristics

N=103 31(30)

N=52

N=51

Distant relapse

intracranial

11(21)

20(39)

0.36

Distant relapse

19(18)

7(13)

12(24)

0.21

Perilesional edema

5

2

3

Vomiting

Headache

4

1

3

Radionecrosis

2

1

1

0.73

1

0

1

Systemic

functional