Assessment of toxicity and clinical outcomes with SBRT in lung metastases: A single institute experience

Abstract

Background: Stereotactic body radiation therapy (SBRT) can help deliver a high biologically equivalent dose to the tumor volume in a small number of fractions with a steep dose fallout on surrounding healthy tissues. A retrospective analysis was performed on patients treated for lung oligo-metastatic disease fromvarious histopathologies. Methods: A total of 155 patients were retrospectively assessed who were diagnosed with lung metastases in various primary malignancies. Clinical outcomes in the form of local control (LC), overall survival (OS) and progression free survival (PFS) were assessed. Toxicity was scored according to CTCAE grading. Univariate analysis was performed to correlate various prognostic factors associated with the disease and grade of toxicities associated. Patients were followed up and assessed for late toxicities as per the institution protocol. Results: The median follow up was 22 months. Colorectal carcinomas formed the major site of primary disease followed by sarcoma and renal cell carcinoma. LC at 1 and 2 years was 94 and 86% respectively. OS at 1 and 2 years was 90, 68.8% respectively. Both OS and L were impacted by the primary histopathology and also the presence of extrapulmonary disease present. PFS at 1 and 2 years was 87% and 62% respectively. Primary histopathology, presence of extrapulmonary disease and age showed a correlation with prognosis at univariate analysis. The treatment follow-up showed no significant late toxicities and Grade 3 and 4 toxicities were not seen in the cohort. Conclusions: The study suggests the role of SBRT as a treatment option for oligometastases in the lung. However, the factors mostly influencing prognosis were the presence of extra-pulmonary disease and the number of lung lesions. With lower number of metastases to treat, the outcome is found to be better.