Session Item

To analyze the outcomes of breast cancer lung metastasis (BCLM) treated with stereotactic body radiotherapy (SBRT) and systemic treatment.

The treatment outcomes of 27 breast cancer patients with de novo oligometastases or oligorecurrence (≤ 5 metastases) to lung after systemic treatment were assessed. A total of 35 lung metastasis (LM) were included in the evaluation. All lesions were treated with SBRT in a median 3 fractions (range, 2-10 fractions) to a total dose of 50 Gy (range, 17-60 Gy) between May 2011 and October 2019. The local control (LC), overall survival (OS), and progression-free survival (PFS) rates were calculated using Kaplan-Meier analyses.

Median age was 48 years (range 32 – 84 years). Median follow-up was 26 months (range 2 – 50 months). Among the 27 patients, 19 (70.4%) had solitary LM while 8 patients (29.6%) had two simultaneous lesions. Estrogen receptor (ER) and progesterone receptor (PR) were positive in 14 patients (51.9%) and 11 patients (40.7%), respectively. All patients had mastectomy for primary disease, and 23 patients (85.2%) received postoperative adjuvant chemotherapy and radiotherapy, while 4 patients (14.8%) had adjuvant chemotherapy only. Most of the patients [24 patients (88.9%)] developed LM during the follow-up of initial treatment, while only 3 patients (11.1%) had LM at the time of first diagnosis. At the last visit, 16 patients (59.3%) had disease recurrence median 11 months (range 3 – 43 months) after completion of lung SBRT.  Median OS and PFS were 32.1 months [95% confidence interval (CI) 17.3– 46.8 months]) and 11 months (95% CI; 4.7 – 17.3 months), respectively. The 1-year PFS and OS rates were 47% and 62%, respectively. Seven patients (25.9%) had local recurrences. None of the patients experienced grade ≥3 acute or late toxicities. 

This study is the first to evaluate the feasibility of SBRT to BCLM patients in a relatively larger patient cohort. Our findings support that the lung SBRT is a feasible and safe method for BCLM with acceptable LC and toxicities. Future prospective studies are warranted to observe the effect on survival in breast cancer patients.