Main Session
Sep
29
PQA 07 - Head and Neck Cancer, Lung Cancer/Thoracic Malignancies, and Nursing and Supportive Care
3471 - Safety and Efficacy of Lung SBRT in Locally Recurrent/Metastatic Carcinomas Alone or in Combination with Concurrent Systemic Therapy
Presenter(s)
Ashwin Ganesh, MD - University of Southern California (USC) /LA General Medical Center, Los Angeles, CA
A. V. Ganesh1, S. Karipineni2, W. L. J. Ho3, B. Tang4, S. Cen5, and J. C. Ye1; 1Department of Radiation Oncology, University of Southern California Keck School of Medicine, Los Angeles, CA, 2Santa Clara Valley Medical Center, San Jose, CA, 3Morsani College of Medicine, University of South Florida, Tampa, FL, 4Keck School of Medicine, Los Angeles, CA, 5Department of Radiology, University of Southern California Keck School of Medicine, Los Angeles, CA
Purpose/Objective(s):
Stereotactic Body Radiotherapy (SBRT) is used for definitive management of lung tumors alone or with concurrent systemic therapy. Due to toxicity concerns, systemic therapy is often held during SBRT. This single-institution retrospective study evaluated whether concurrent systemic therapy increases radiation-related toxicity in patients receiving lung SBRT.Materials/Methods:
We reviewed 170 patients with locally recurrent NSCLC or metastatic lung disease who received 233 lung SBRT treatments from 2014–2023, either alone or with concurrent systemic therapy (SBRT-s), defined as chemotherapy, immunotherapy, or targeted therapy delivered withing 30 days of RT. SBRT was defined as lung RT treatment in = 15 fractions and BED10 = 48 G. Logistic regression assessed associations with pneumonitis; variables with p<0.1 on univariate analysis (UVA) were included in multivariate analysis (MVA). Factors analyzed in MVA included tumor centrality, endobronchial invasion, BED10, maximal proximal bronchial tree dose, Lung V20, and line of systemic therapy before SBRT. Univariate and Multivariate Linear regression evaluated local control (LC), progression-free survival (PFS), and overall survival (OS). BED10 was modeled continuously using Cox regression with restricted cubic splines to determine the optimal BED10 associated with OS.Results:
86 (36.9%) of treatments were SBRT-s and 106 (63.1%) of treatments were SBRT slone. Of the SBRT-s patients, 38 received concurrent chemotherapy, 52 received concurrent immunotherapy, and 16 received concurrent targeted therapy. Median follow-up was 26.9 months. There were 49 instances (46.2%) of pneumonitis in the SBRT-s arm (22 grade 1, 26 grade 2, 1 grade 3) and 37 instances (43.0%) of pneumonitis in the SBRT arm (20 grade 1, 17 grade 2). On MVA, concurrent systemic therapy of any type was not associated with pneumonitis of any grade (OR 1.32, 95% CI 0.69-2.53, p=0.403). There were 12 instances of cardiac toxicity in the SBRT-s group (1 grade 1, 5 grade 2, 3 grade 3, 2 grade 4, and 1 grade 5) and 5 in the SBRT group (1 grade 1, 2 grade 2, 1 grade 3, and 1 grade 4). There were 5 instances of esophagitis (all grade 2) in the SBRT-s group compared to 9 instances in the SBRT alone group (3 grade 1 and 6 grade 2). 2-year OS (54.4% vs 37.2%, p=0.016) and PFS (28.6% vs 12.8%, p=0.009) favored SBRT-s on UVA while 2-year LC did not differ on UVA (47.6% vs 36%, p=0.113). On MVA, concurrent systemic therapy was not significantly associated with OS (ß=-3.04, 95% CI -13.01-7.01, p=0.55), PFS (ß=-1.86, 95% CI -11.59-7.87, p=0.71), or LC (ß=-3.03, 95% CI -12.48-6.41, p=0.53). The optimal BED10 determined on cut-point analysis associated with OS and LC was 96Gy (p<0.001).Conclusion:
Concurrent systemic therapy was not associated with a significantly greater risk of radiation-related toxicities, without impacting OS, PFS, or LC. In patients who are at high-risk of short-term progression during SBRT, concurrent systemic therapy should be considered at provider discretion.