P3.08-02 Oligometastatic Non Small Cell Lung Cancer Patients Treated with Stereotactic Body Radiotherapy (SBRT), a Single Institution Experience

Abstract

Oligometastatic disease is an intermediate state between localized and widespread diffuse disease. By definition, this state is amenable to local ablative approaches, like Stereotactic Body Radiation Therapy (SBRT), with curative intent. Patients treated with SBRT for oligometastatic NSCLC (max 5 active lesions in max 3 different organs) between January 2014 and December 2015 in the Radiotherapy and Radiosurgery department of the Humanitas Clinical and Research Hospital were retrospectively analyzed. Primary endpoint of the study was local contro (LC)l; overall survival (OS), disease metastases free survival (DMFS) and progression free survival (PFS) were analyzed as well. LC and survival times were calculated from the first day of SBRT. Best local response (BLR) was defined according to RECIST criteria. 83 patients were included in the study. Patients received different RT schedules according to number, site and size of the metastases. Treatment was generally well tolerated; no acute or late G3-4 toxicity was recorded. Complete response, partial response or stable disease were recorded in 30 (35%), 40 (47%) and 14 (16%) patients respectively. One patient had a local progression at first evaluation, while other 16 (19%) patients experienced local relapse during follow up. Actuarial local control time at 6, 12 and 24 months was 91.73%, 84.95% and 77.82% respectively. Distant progression was recorded in 64 patients (75%), in most cases (54 patients, 84%) patients progressed again in a oligometastatic way. Actuarial DMFS at 6, 12 and 24 months was 60.97%, 36.9% and 23.36% respectively. Actuarial PFS at 6, 12 and 24 months was 60.1%, 37% and 22% respectively. With a median follow up time of 20 months (range 4.9-49.9), 33 patients (39%) were still alive, in 8 cases with no evidence of disease. Actuarial median overall survival (OS) was 24.5 months, OS at 6, 12 and 24 months was 97.6%, 81.6% and 50.2%. At univariable analysis type of oligometastases (p=0.015) and BLR (p=0.000) were found to be correlated with LC. Previous local ablative treatments (p=0.04, p=0.033), site of the irradiated lesion(s) (p=0.0016, p=0.0026), “adjuvant” medical therapies (p=0.0278, p=0.023) and BLR (p=0.011, p=0.018) correlated with DMFS and PFS. Site of irradiated lesion (p=0.000), RT BED (p=0.0019) and BLR (p=0.000) were statistically correlated with OS. SBRT for oligometastatic NSCLC is safe and effective. Local response is strongly correlated with patients’ prognosis, underlying the relevance of local control also in a metastatic setting.