Dose escalation improves outcome in stereotactic body radiotherapy for pulmonary oligometastases from colorectal cancer

Aim: To evaluate the efficacy of stereotactic body radiotherapy (SBRT) for pulmonary metastasis from colorectal cancer. Patients and Methods: Data for 104 lesions from 93 patients who underwent SBRT for pulmonary oligometastases from colorectal cancer at ten Institutions were retrospectively analyzed. Toxicity was graded according to the Common Terminology Criteria for Adverse Events v4.0. Results: The median calculated biological effective dose using the linear-quadratic model with α/β of 10 Gy (BED10) was 105.6 Gy. Adjuvant chemotherapy after SBRT was performed in 47 patients. The median observation period was 28 months. The 3- and 5-year local control rates were 65.2% and 56.2%, respectively. The 3- and 5-year overall survival rates were 55.9% and 42.7%, respectively. Only two patients had grade 3 radiation pneumonitis. In multivariate analysis for local control, primary site, age, adjuvant chemotherapy after SBRT and BED10 were selected as prognostic factors. Conclusion: Dose escalation and adjuvant chemotherapy might improve local control in SBRT for pulmonary oligometastases from colorectal cancer.