Stereotactic Ablative Radiation Therapy for Pulmonary Metastases: Histology, Dose, and Indication Matter

To assess the association between colorectal cancer (CRC) histology, dose, and local failure (LF) after stereotactic ablative radiation therapy (SABR) for pulmonary metastases, and to describe subsequent cancer progression, change of systemic therapy (CST), survival, and their association with treatment indications. From a prospective SABR cohort, 180 pulmonary metastases in 120 patients were identified. Treatment indications were single metastasis, oligometastases, oligoprogression, and dominant areas of progression. Doses of 48 to 52 Gy/4 to 5 fractions were delivered. Since 2010 the dose for peripheral CRC metastases was increased to 60 Gy/4 fractions. Cumulative incidence function (CIF) was used to report LF, progression probability, and CST. The Kaplan-Meier method estimated overall survival (OS). Univariate and multivariable analyses to assess variable associations were conducted. Median follow-up was 22 months (interquartile range, 14-33 months). At 24 months, the CIF of LF was 23.6% (95% confidence interval [CI] 15.1%-33.3%) and 8.3% (95% CI 2.6%-18.6%), respectively, for CRC and non-CRC metastases (P