Author: Baher Elgohari, M. Saiful Huq, Ronald John Lalonde, Fang Li, Noor Mail, Jeonghoon Park, Tyler Wilhite 👨🔬
Affiliation: UPMC Hillman Cancer Center and University of Pittsburgh School of Medicine, Department of Radiation Oncology, UPMC Hillman Cancer Center, UPMC, Department of Medical Physics, Memorial Sloan Kettering Cancer Center 🌍
Purpose:
To compare toxicity between consecutive-daily (QD) with every-other-day (QoD) delivery of lung stereotactic-body-radiation (SBRT) for central non-small-cell lung cancer (NSCLC).
Methods: Tumors that were treated with SBRT within 2 cm of the proximal-bronchial-tree were retrospectively reviewed. Patients treated from 2018-2020 received QoD SBRT (Group-1). Patients treated from 2020-2022 received QD SBRT (Group-2); these patients also received ITV boost up-to 110-120% of the prescription dose (Rx). All normal tissue contours were retrospectively regenerated with auto-contouring software and dosimetric indices were collected and compared. Additionally, normal tissue toxicities were compared.
Results: 118 patients were included: 57 in Group-1 and 61 in Group-2. Median follow-up was 27.5 months (Group-1) and 27.9 months (Group-2). In Group-2, the GTV received significantly higher dose than in Group-1 (114% vs. 102% of Rx, p=0.000), with an average ITV boost of 112% of the Rx. Both groups had similar PTV coverage (D98%: 98.5% Group-1 vs. 99.9% Group-2). All Region of Interest (ROI) doses were comparable except for the maximum doses to heart and spinal cord. The heart maximum dose was significantly higher in Group-1 (14.9 Gy vs. 9.8 Gy, p=0.03), while the maximum spinal cord dose was higher in Group-2 (7.4 Gy vs. 9.0 Gy, p=0.01).
Pneumonitis and chest-wall pain were observed in 7 patients (5 Group-1, 2 Group-2; P=0.21). No esophagitis, hemorrhage, cardiac toxicity, or bronchial injury were observed.
Conclusion:
SBRT delivered QD with an ITV boost was well tolerated and did not result in any increased toxicity in the treatment of central tumors. Further studies are warranted to assess any differences in clinical outcomes associated with QD vs. QoD delivery of lung SBRT.