M. Loi1, V. Salvestrini2, V. Luzzi3, G. Simontacchi1, D. Greto1, G. Francolini1, V. Di Cataldo1, P. Bonomo1, P. Garlatti1, E. Olmetto1, C. Becherini1, I. Desideri4, L. Marrazzo5, S. Tomassetti6, L. Livi4, and S. Pallotta7; 1Radiation Oncology, Careggi University Hospital, University of Florence, Florence, Italy, 2Istituto Fiorentino di Cura e Assistenza (IFCA), CyberKnife Center, Florence, Italy, 3Interventional Pneumology, Careggi University Hospital, Florence, Italy, 4Department of Experimental Clinical and Biomedical Sciences “Mario Serio”, University of Florence, Florence, Italy, 5Department of Biomedical, Experimental and Clinical Sciences "Mario Serio", University of Florence, Florence, Italy, Florence, Italy, 6Department of Experimental and Clinical Medicine, University of Florence, Florence, Italy, 7University of Florence, Department of Biomedical, Experimental and Clinical Sciences “Mario Serio", Florence, Italy
Purpose/Objective(s): The use of ablative Stereotactic Body Radiotherapy for the treatment of mediastinal and hilar lymphnodal metastases (MHL) has been traditionally limited due to proximity of critical organs and uncertainty in target recognition and treatment administration due to respiratory motion, potentially resulting in fatal adverse events. Fiducial-markers implanted via EBUS may allow delivery of ablative SBRT by Real-time tumor tracking (RTTT) or by refining CBCT image guidance. We report preliminary follow-up data from an observational prospective clinical study (FLUXUS) assessing the use of ablative SBRT in oligometastatic or oligoprogressive MHL. Materials/
Methods: Data from a prospective cohort of patients treated from December 2021 to December 2023 with ablative SBRT for oligometastatic or oligoprogressive MHL from miscellaneous primary tumors were collected. Gold-anchor 25G FM were placed intralesionally via EBUS under general anesthesia following rigid bronchoscopy. One week later, blank and contrast enhanced simulation CT was acquired: in order to verify the solidarity between the FM and the tumor across the respiratory cycle an additional 4D CT was obtained. SBRT was delivered using RTTT with a robotic-arm linac or surface and CBCT guided deep-inspiration breath hold (DIBH). Preliminary outcome and toxicity results were assessed. Results: Eighteen patients, accounting for 21 MHL were included. Median age was 73 (range 48-87) years. Median follow-up was 6 months. Primary tumor location were lung (n=8), breast (n=4), gastroesophageal (n=3), and other (n=3). Disease setting was oligometastatic and oligoprogressive MHL in 7 and 11 patients, respectively. MHL were located in nodal station 10-11 (n=7), 4 (n=6), 7 (n=5), 2-3 (n=2) and 8 (n=1). Median number of implanted FM was 3 (range 2-3): no periprocedural complication or migration was observed. RTT and DIBH were used in 15 and 3 patients, respectively. In 3 patients, 2 MHL were simultaneously treated during the same treatment course, the remaining patients receiving SBRT to a single nodal site. Median prescription dose was 35 Gy (range, 30-40 Gy) in 5 fractions, corresponding to a median EQD2 of 49.5 Gy (range, 48-100 Gy) assuming a/ß=10. Local control (LC) was 95% at 1 year. Distant relapse-free (DRFS) and overall survival (OS) were 54% and 73% at 1 year, respectively. All 6 patients who were chemotherapy-naïve before SBRT were free from systemic therapy at the time of the analysis. Acute transient toxicity, consisting of grade 1 cough and pyrosis was observed in 2 patients. Only one patient experienced a grade=3 late toxicity, consisting of aorto-oesophageal fistula resulting in fatal hematemesis. Conclusion: FM placement is a minimally invasive and well tolerated procedure in elderly patients and allow the delivery of ablative SBRT to MHL with promising outcome and toxicity results. Caution is required in case of suspicion of mediastinal organ infiltration.
