2407 - Single-Fraction Lung SBRT for Primary and Metastatic Lung Tumors: Ten-Year Experience
Presenter(s)
L. Larrea1, E. Lopez2, M. C. Banos3, J. Lago2, and M. A. Berenguer Francés4; 1Hospital Vithas Valencia Consuelo - GenesisCare, Valencia, Spain, 2Hospital Vithas Valencia Consuelo, Valencia, Spain, 3Hospital Valencia Vithas Consuelo, Valencia, Spain, 4Hospital Vithas Valencia Consuelo - Genesis Care Spain, valencia, Spain
Purpose/Objective(s): The aim of this study is to review 10 years of single-fraction lung stereotactic body radiation therapy (SF-SBRT) evaluated in terms of survival, local control and toxicity.
Materials/Methods: Between 2002 and 2023, 364 patients with 412 lung tumors were treated with SBRT at our institution. Of those,65 lesions in 57 patients were treated using a SF-SBRT 30 Gy fraction between 2013 to 2023. The main decision factors for selecting SF-SBRT include peripheral lung lesions and diameters less than 4 cm. The SBRT procedure involved slow-scan CT simulation with immobilization devices, contouring the target volume in 3 sets of CT to define GTV, ITV and PTV, and dose calculation using heterogeneity correction. Radiation therapy plan and delivery was 3D, IMRT or VMAT. The prescribed dose was 30-Gy single fraction with at least 95 % of the ITV covered by the 95% isodose volume. Dosimetric constraints were established for the surrounding organs at risk. Three cone-beam CT scans (2 previous and 1 after radiation administration) were performed to verify, adjust positioning and quality assurance. Toxicity and radiologic response were assessed in follow- up visits, using standardized criteria (RTOG and RECIST) and analyzed retrospectively. Survival rates and toxicities were calculated using the Kaplan-Meier method.
Results: The median patient age was 71 years (51-87). All patients had a good performance status at the moment of treatment (ECOG PS 0-1). Because of the patient's comorbidities or preferences, none were surgical candidates. The FEV1 was over 30 % of the predicted value in all cases. 60 % of all patients also received systemic treatment before or after SBRT. 89,3 % of the patients had 18- FDG PET-CT prior to SBRT. There were 23 primary tumors (T1N0M0: 7 adenocarcinoma, 4 epidermoid, 2 undifferentiated non-small cell lungcancer and 12 PET positive tumors without histology determined) and 42 oligometastases from various origins (23 colo-rectal, 16 contralateral lung non-small cell cancer, 1 thyroid, 1 renal cell, 1 sarcoma). The tumor ITV was 3.4 cc (0.6-24.3). No acute toxicities grade III or more was identified. In the follow-up CT, 5 patients had asymptomatic radiation neumonitis. The overall median follow-up was 61 months (9 - 130). The overall survival rates for the 1, 2 and 5-year were 93, 73 and 54%. The cancer-specific survival for the 1, 2 and 5-yearwere: 95%, 80% and 60%. Local control in the irradiated volume is 99,3 %, with 11 distant thoracic (outside irradiated volume) recurrences.
Conclusion: In selected patients with primary and metastatic lung tumors, SF-SBRT is an excellent treatment option in terms of survival, local control and toxicity. Outcomes from this analysis are comparable to published results and validate the use of this schedule in routine practice. In the absence of phase 3 trials, this study should encourage increased use of SF-SBRT for inoperable tumors.