Stereotactic radiation therapy of cerebral metastases in patients with breast cancer. Clinical spectrum and prognosis

Mette Møller (1), Yasmin Alexandra Lassen (1), Anders Bonde Jensen (1)

1) Department of Oncology, Aarhus University Hospital, Aarhus, Denmark

Background
Stereotactic radiation therapy (SRT) can be used for treatment of cerebral metastases, yet data describing the use of SRT in patients with breast cancer remain sparse. Therefore, we investigated patients with breast cancer and cerebral metastases treated with SRT in order to elucidate the clinical characteristics and outcome of the treatment.

Materials and methods
We conducted a retrospective study of all patients with breast cancer and cerebral metastases treated with first-time SRT at the Department of Oncology, Aarhus University Hospital, 2001 through 2015. Patients were identified by searching patient files and local hospital databases and all data were abstracted from the patient records. We characterized the study population using descriptive statistics and assessed the 3-year survival by the Kaplan-Meier method. Finally, we ascertained the occurrence of new cerebral metastases after SRT.

Results
Forty-five female patients with breast cancer and SRT-treated cerebral metastases were identified. Median age at the time of breast cancer diagnosis was 58 years (interquartile range (IQR), 46-61). Median time from breast cancer diagnosis to diagnosis of cerebral metastases was 3.4 years (IQR, 1.1-5.9). Size of the metastases was in the majority of the cases <20mm (n=25, 56%), and most patients had solitary cerebral metastasis (n=31, 69%). Survival after SRT was at one year 59.3% (95 CI, 43.4-72.2), after two years 19.9% (95% CI, 9.0-33.8), and 11.4% (95% CI, 3.7-23.9) after three years. A total of 23 patients (51%) were diagnosed with new cerebral metastases after first-time SRT during two years of follow-up (median time from first-time SRT to diagnosis of new cerebral metastases was 149 days (IQR, 111-273)). The majority of patients with new metastases were treated with whole brain radiation (n=14, 61%), 7 patients (30%) had surgery, 5 patients (22%) received additional SRT, and only 2 patients (9%) were not offered further treatment for their cerebral metastases.

Conclusion
Patients with breast cancer and cerebral metastases treated with first-time SRT had a high one-year survival at 59% and only half of the patients developed further brain metastases within two years of follow-up.