Stereotactic body radiotherapy for pulmonary oligometastases: amonoinstitutional analysis of clinical outcomes and potential prognostic factors.

Abstract

We report the retrospective data of acohort of patients who received stereotactic body radiotherapy for pulmonary oligometastases, aiming to assess the clinical factors potentially affecting clinical outcomes. The present series reports the outcomes of acohort of 71patients with pulmonary oligometastases with no extrapulmonary disease. All patients were treated with stereotactic body radiotherapy (SBRT) performed with volumetric modulated arc therapy-image guided radiotherapy (VMAT-IGRT) to up to five secondary lesions. Survival estimates were performed using the Kaplan-Meier method. Atotal of 98lesions in 71patients were treated from February 2014 to August 2020. The most frequent histologies were colorectal in 37.7%, lung cancer in 44.8%, head and neck cancer in 8.1%, and other in 9.4%. Median age was71years (range 32-93years). Concurrent systemic therapy was administered in 32.3%. SBRT was delivered to amedian total dose of 60 Gy (range 55-70 Gy) in 3-10fractions for amedian BED10 = 105 Gy (range 96-180 Gy). Median follow-up was 29.5months (range 6-81), with no acute or late G > 2 adverse event. Our LC rates at2 and 4years were 92.4 and 89.8%, respectively. DPFS rates at 2 and 4years were 45.3 and 27.2%, respectively. Asecond SBRT course was proposed in 21patients (29.5%) who developed an oligoprogression, resulting in median time to second progression of 9months (range 2-44) and 2‑year PFS2 rate of 42.4%. At univariate analysis, patients with sequential oligometastases reported better OS rates (p = 0.002), which was also confirmed at multivariate analysis, where distant progression was also related to worse OS (p = 0.022). Higher local control rates relate to better PFS (p = 0.04). The 2‑ and 4‑year OS rates were 61 and 39.7% CONCLUSION: SBRT is feasible for pulmonary oligometastases with favorable outcomes and toxicity. At multivariate analysis, patients with sequential oligometastatic progression maintain asurvival advantage. Also, local control was found to be related to improved PFS rates.