Active breathing control guided stereotactic body ablative radiotherapy for management of liver metastases from colorectal cancer

Background: Liver metastases may occur during the course of several cancer types and may be associated with significant morbidity and mortality. There is paucity of data regarding the utility of Active Breathing Control (ABC) guided Stereotactic Ablative Body Radiotherapy (SABR) for management of Liver Metastases from Colorectal Cancer (LMCC). Our aim is to investigate the role of ABC guided SABR for management of liver metastases

Patients and methods: 42 liver metastases of 29 patients treated with ABC guided SABR between February 2015 and October 2018 were retrospectively assessed for local control (LC), overall survival (OS), and toxicity outcomes. Primary endpoint was LC. Secondary endpoints were OS and treatment toxicity.

Results: At a median follow up duration of 16 months (range: 9-74 months), median OS was 20 months and 3 patients were still alive at last follow up. 1-year OS was 83% and 2-year OS was 28%. LC rates were 92% and 61% at 1 and 2 years, respectively. Comparative analysis of Biological Effective Dose (BED) values revealed that higher BED10 values were associated with higher LC rates (p=0.007). While LC rates for BED10 ≥ 100 Gray (Gy) were 94% and 86% at 1 and 2 years, corresponding LC rates for BED10 < 100 Gy were 89% and 36%, respectively with statistical significance (p=0.007). Assessment of acute and late toxicity outcomes revealed that most common toxicity was fatigue, however, no patients had ≥ grade 3 toxicity.

Conclusion: ABC guided SABR is an effective and safe treatment modality for LMCC management.

Keywords: active breathing control, stereotactic body ablative radiotherapy, colorectal cancer, liver metastases.