Stereotactic body radiotherapy (SBRT) for oligometastatic lung tumors from colorectal cancer and other primary cancers in comparison with primary lung cancer

Purpose: To analyze local control of oligometastatic lung tumors (OLTs) compared with that of primary lung cancer after stereotactic body radiotherapy (SBRT). Materials and methods: Retrospective record review of patients with OLTs who received SBRT with 50 Gy in 5 fractions. Local control rates (LCRs), toxicities, and factors of prognostic significance were assessed. Results: Twenty-one colorectal OLTs, 23 OLTs from other origins, and 188 primary lung cancers were included. Multivariate analysis revealed only tumor origin was prognostically significant (p < 0.05). The 1-year/2-year LCRs in colorectal OLTs and OLTs from other origins were 80%/72% and 94%/94%, respectively. The LCR in colorectal OLTs was significantly worse than that in OLTs from the other origins and primary lung cancers with pathological and clinical diagnosis (p < 0.05, p < 0.0001 and p < 0.005). Among 44 OLT patients, Grades 2 and 3 radiation pneumonitis were identified in 2 and 1 patients, respectively. No other toxicities of more than Grade 3 occurred. Conclusion: SBRT for OLTs is tolerable. The LCR for OLTs from origins other than colorectal cancer is excellent. However, LCR for colorectal OLTs is worse than that from other origins. Therefore dose escalation should be considered to achieve good local control for colorectal OLTs.