MA01.11 Improving Survival in Lung Cancer Patients with Oligometastatic Disease Progression Using Stereotactic Body Radiation Therapy

Abstract

In patients (pts) with stage IV non-small cell lung cancer (NSCLC) receiving systemic therapy, stereotactic body radiation therapy (SBRT) can eliminate oligometastatic disease progression (OMP). This allows NSCLC pts to continue the same systemic therapy, and its is especially important when the therapy is well tolerated as is the case for many pts receiving immunotherapy (IMMUNO) and targeted therapy (TARGET). The purpose of this study is to quantify the progression free survival (PFS) and overall survival (OS) of pts receiving systemic therapy who experience OMP that is treated with SBRT, and subsequently continue the same systemic therapy. Retrospective review of one hundred pts with metastatic NSCLC undergoing chemotherapy (CHEMO), IMMUNO or TARGET that had OMP defined as less than 4 sites of metastasis and underwent SBRT were evaluated for PFS and OS. PFS1: Time between initiation of systemic therapy and development of OMP. PFS2: Time between OMP treated with SBRT and development of further PD requiring a change in systemic therapy. Pts received IMMUNO for second line and beyond. SBRT doses were determined based on the disease site and dose tolerance of the adjacent organs. SBRT was delivered in 1-5 fractions on consecutive days or every other day. Radiation dose was determined by target volume and adjacent dose-limiting organs. OMP presented as brain metastasis (BM) in 45 pts and extracranial metastasis (EM) in 55 pts. 34 pts were receiving CHEMO, 34 TARGET and 32 IMMUNO at the time of OMP. Pts with BM that received SBRT were able to continue the same therapy for a period of 6.5-9 extra months due to the control of BM. Pts with EM that have developed PD were able to continue the same therapy an 17-21 extra months due to the ablation of OMP by SBRT. For the entire cohort PFS was: 16.5m for BM and 34m for EM and the OS were: 31m and 53m respectively.Tabled 1Location of oligometastatic progression (OMP)Median PFS1Median PFS2PFSMedian OSExtracranial (N=55)13213453chemo7172447Immuno13.520.53449Target12213353Brain (N=45)97.516.531Chemo5.56.51225.5Immuno781527Target1192047 Open table in a new tab PFS and OS may be prolonged due to the use of SBRT in pts that develop OMP. This intervention allowed patients to continue with the same systemic treatment. Our CHEMO cohort is composed of long term survivors under therapy and may not represent the average PFS/OS of pts on CHEMO. Prospective trials are needed to verify these results.