Stereotactic Body Radiation Therapy for Pulmonary Metastasis from Colorectal Adenocarcinoma: Biologically Effective Dose 150 Gy is Preferred for Tumour Control

AimsTo compare the local control rate of pulmonary metastatic lesions in colorectal adenocarcinoma treated with stereotactic body radiation therapy (SBRT) using a biologically effective dose with an α/β ratio of 10 (BED₁₀) of 150 Gy.Materials and methodsWe analysed 231 pulmonary metastatic lesions from colorectal adenocarcinoma treated with SBRT in 135 patients. The patients were referred for the control of oligometastatic or oligoprogressive disease in the lungs. A dose of 40–60 Gy in three to eight fractions was delivered. The local control per tumour (LCpT) by BED₁₀ was evaluated. The local control per patient (LCpP), pulmonary progression-free survival (PPFS), any progression-free survival (APFS) and overall survival were also reported as clinical outcomes.ResultsA significant difference was observed in the LCpT between the BED₁₀ groups (P < 0.001). The 1-, 2- and 3-year LCpT were 38.9%, 25.9% and 25.9% in BED₁₀ < 100 group; 84.1%, 62.6% and 60.4% in 100 ≤ BED₁₀ < 150 Gy group; and 97.3%, 94.9% and 85.2% in BED₁₀ ≥ 150 Gy group, respectively. BED₁₀ ≥ 150 Gy remained significant in the multivariate analysis of LCpT. The 3-year LCpP, PPFS, APFS and overall survival rates were 62.7%, 26.5%, 24.8% and 67.7%, respectively. Oligoprogression (versus oligometastasis), multiple pulmonary nodules and extrapulmonary metastasis were associated with a poor prognosis.ConclusionA BED₁₀ ≥ 150 Gy may be required to achieve sufficient local control. The indications for SBRT and the extent of metastatic disease should be assessed for proper estimation of the clinical outcomes.