Prognostic factors for local control and survival for inoperable pulmonary colorectal oligometastases treated with stereotactic body radiotherapy.

Abstract

The study aimed to evaluate overall survival and local control, and to identify factors independently associated with overall survival (OS) and local control (LC). This retrospective study examined 118 patients with primary colorectal cancer, in whom 202 inoperable pulmonary oligometastases were treated with stereotactic body radiotherapy between 2005 and 2015. Primary endpoint was to evaluate OS and identify prognostic factors associated with OS. Secondary aim was to evaluate LC and identify prognostic factors associated with LC. Median follow-up was 31 months (range 3-88 months). Median OS was 39.2 months (95% CI 34.8-43.6 months). Two-, three-, and five-year OS was 69%, 55% and 36%, respectively. LC at 2-, 3-, and 5-year was 83%, 81% and 77% respectively. Factors independently associated with OS in the multivariable analysis included BED₁₀ ≥ 100 Gy (HR 0.52), male gender (HR 0.52), age < 70 years (HR 0.52) and presence of single metastasis (HR 0.37). BED₁₀ < 100 Gy (HR 3.67) and pre-SBRT chemotherapy (HR 2.66) were independently associated with poor LC in a multivariable analysis. SBRT was associated with 2- year OS of 69% and 2-year LC of 83%. SBRT dose ≥ 100 Gy BED₁₀ was independently associated with both better overall survival and local control.