Multi-institutional analysis of extracranial oligometastatic colorectal cancer patients treated with stereotactic body radiation therapy: TROD 02-008 study

Abstract

Purpose To investigate the treatment outcomes of extracranial oligometastatic colorectal cancer (CRC) patients treated with stereotactic body radiotherapy (SBRT). Materials and methods The clinical data of 388 extra-cranial oligometastatic CRC (<= 5 lesions) patients and 463 lesions treated with SBRT at 19 cancer institutions were retrospectively analyzed. The prognostic factors predicting overall survival (OS), progression-free survival (PFS), and local control (LC) were assessed in uni- and multivariable analyses. Results The median age was 62 years (range, 29-92 years). The majority of the patients (90.5%) received surgery and systemic treatment for their primary tumor, had <= 2 metastasis (83.3%), had single organ involvement (90.3%), and staged using flouro-deoxyglucose positron emission tomography (FDG-PET/CT) (76%). The median fraction and total radiation doses were 10 Gy (range: 6-34 Gy) and 50 Gy (range: 8-64 Gy), respectively, delivered in a median of 4 fractions (range: 1-8). The median follow-up time for the entire cohort was 30.7 months (interquartile range: 27.0-34.3 months). The 3-year OS, PFS, and LC rates were 64.0%, 42.3%, and 72.7%, respectively. The 3-year LC rate was significantly higher in patients receiving BED10 >= 100 Gy than those receiving BED10 < 100 Gy (76.0% vs. 67.3%; p = 0.04). The 3-year PFS and OS rates were higher in patients receiving BED10 >= 100 Gy than those receiving BED10 < 100 Gy (33.2% vs. 25.2%; p = 0.03; 53.7% vs. 44.8%; p = 0.02). Single metastasis and complete response after SBRT were independent prognostic factors for survival in multivariable analysis. Conclusions In this multi-center study, we demonstrated that SBRT is an effective treatment option of metastatic lesions in oligometastatic CRC patients by providing promising LC rates. Higher SBRT doses beyond BED10 >= 100 Gy were associated with improved LC and survival. LC of treated lesion and lower tumor burden after SBRT were associated with better outcomes.