The Impact of Tumor Volume in Breast Cancer Liver Metastasis Patients Treated with Stereotactic Radiotherapy – Does Size Matter?

Abstract

To investigate the relationship between tumor volume and survival in breast cancer liver metastasis (BCLM) patients treated with stereotactic radiotherapy. 39 biopsy proven breast cancer patients whom liver metastasis was treated with stereotactic radiotherapy (SRT) were retrospectively investigated. Patient characteristics, survival and their relation with tumor volume were analyzed. Median age was 47 years (range; 27-78 years). Median tumor size was 1.8 ± 1.1 cm. Median gross tumor volume (GTV) and planning tumor volume (PTV) were 6.8 cc (range, 0.7-55.2 cc) and 38.7 cc (range; 9.3-163.8 cc), respectively. SRT dose prescription was 3 fr x 18 Gy in 37 patients (96%), 3 fr x 20 Gy in 1 patient (2%) and 3 fr x 16 Gy in 1 patient (2%). 13 patients (33%) had solitary liver metastasis while 26 patients (67%) also had other organ metastases beyond liver. Median follow-up for entire cohort was 15.4 months (range; 1-49 months). At last visit 26 patients (67%) had disease progression. Among these patients 25 patients (64%) had distant metastasis while 2 patients (5%) had isolated local recurrence. The 1- and 2- years overall survival (OS) rates were %79.1 and %46.0, respectively. Median OS was 23.8 months (95% CI: 13.3-34.3 months). 1 and 2-years progression-free survival (PFS) rates were 38.1% and 11.5%, respectively. Median PFS was 8.7 months (95%CI: 5.6-11.8 months). 1 and 2-years of local control (LC) per tumor were 92.9% and 85%, respectively. Patients were divided into two groups according to tumor volume £30 cc or >30 cc. 1-year OS was 100% for patients with tumor volume £30 cc while 1-year OS was 34% for patients with tumor volume > 30 cc (p = 0.04). 4 patients developed grad 3 late toxicity. Among them 1 had duodenal ulcer, received medical treatment without any surgical intervention and 3 of them had rib fracture treated with symptomatic medical treatment. SRT is an efficient treatment with optimal LC and low toxicity profile in BCLM patients. Tumor volume of £30 cc had better survival.