Magnetic Resonance-Guided Stereotactic Body Radiation Therapy/Hypofractionated Radiation therapy for Metastatic and Primary Central and Ultracentral Lung Lesions

• Published in: JTO clinical and research reports Vol. 4; no. 5; p. 100488
• Main Authors: Sandoval, Maria L., Sim, Austin J., Bryant, John M., Bhandari, Menal, Wuthrick, Evan J., Perez, Bradford A., Dilling, Thomas J., Redler, Gage, Andreozzi, Jacqueline, Nardella, Louis, Feygelman, Vladimir, Latifi, Kujtim, Rosenberg, Stephen A.
• Format: Journal Article
• Language: English
• Published: United States Elsevier Inc 01.05.2023; Elsevier
• Subjects: Central lung; MR-guided radiotherapy; Original; Radiotherapy; Stereotactic ablative; Ultracentral lung; Central lung; MR-guided radiotherapy; Radiotherapy; Stereotactic ablative; Ultracentral lung
• DOI: 10.1016/j.jtocrr.2023.100488
• ISSN: 2666-3643

The recent results from the Nordic-HILUS study indicate stereotactic body radiation therapy (SBRT) is associated with high-grade toxicity for ultracentral (UC) tumors. We hypothesized that magnetic resonance-guided SBRT (MRgSBRT) or hypofractionated radiation therapy (MRgHRT) enables the safe delivery of high-dose radiation to central and UC lung lesions. Patients with UC or central lesions were treated with MRgSBRT/MRgHRT with real-time gating or adaptation. Central lesions were defined as per the Radiation Therapy Oncology Group and UC as per the HILUS study definitions: (1) group A or tumors less than 1 cm from the trachea and/or mainstem bronchi; or (2) group B or tumors less than 1 cm from the lobar bronchi. The Kaplan-Meier estimate and log-rank test were used to estimate survival. Associations between toxicities and other patient factors were tested using the Mann-Whitney U test and Fisher’s exact test. A total of 47 patients were included with a median follow-up of 22.9 months (95% confidence interval: 16.4–29.4). Most (53%) had metastatic disease. All patients had central lesions and 55.3% (n = 26) had UC group A. The median distance from the proximal bronchial tree was 6.0 mm (range: 0.0–19.0 mm). The median biologically equivalent dose (α/β = 10) was 105 Gy (range: 75–151.2). The most common radiation schedule was 60 Gy in eight fractions (40.4%). Most (55%) had previous systemic therapy, 32% had immunotherapy and 23.4% had previous thoracic radiation therapy. There were 16 patients who underwent daily adaptation. The 1-year overall survival was 82% (median = not reached), local control 87% (median = not reached), and progression-free survival 54% (median = 15.1 mo, 95% confidence interval: 5.1–25.1). Acute toxicity included grade 1 (26%) and grade 2 (21%) with only two patients experiencing grade 3 (4.3%) in the long term. No grade 4 or 5 toxicities were seen. Previous studies noted high rates of toxicity after SBRT to central and UC lung lesions, with reports of grade 5 toxicities. In our cohort, the use of MRgSBRT/MRgHRT with high biologically effective doses was well tolerated, with two grade 3 toxicities and no grade 4/5.