In-field stereotactic body radiotherapy (SBRT) reirradiation for pulmonary malignancies as a multicentre analysis of the German Society of Radiation Oncology (DEGRO)

Caroline John,Panagiotis Balermpas,Frederick Mantel,Judit Boda-Heggemann,Hanno M Specht,Matthias Guckenberger,Franz Zehentmayr,Nicolaus Andratschke,Carmen Stromberger,Eleni Gkika,Riccardo Dal Bello,Oliver Blanck

doi:10.1038/s41598-021-83210-3

Abstract

Data of thoracic in-field reirradiation with two courses of stereotactic body radiotherapy (SBRT) is scarce. Aim of this study is to investigate feasibility and safety of this approach. Patients with a second course of thoracic SBRT and planning target volume (PTV) overlap were analyzed in this retrospective, multicenter study. All plans and clinical data were centrally collected. 27 patients from 8 centers have been amenable for evaluation: 12 with non-small-cell lung cancer, 16 with metastases, treated from 2009 (oldest first course) to 2020 (latest second course). A median dose of 38.5 Gy to the 65%-isodose over a median of 5 fractions was prescribed in the first course and 40 Gy in 5 fractions for the second SBRT-course. Median PTV of the second SBRT was 29.5 cm3, median PTV overlap 22 cm3. With a median interval of 20.2 months between the two SBRT-courses, 1-year OS, and -LCR were 78.3% and 70.3% respectively. 3 patients developed grade 1 and one grade 2 pneumonitis. No grade > 2 toxicity was observed. Peripheral location and dose were the only factors correlating with tumor control. A second SBRT-course with PTV overlap appears safe and achieves reasonable local control.

Highlights

Stereotactic body radiotherapy (SBRT) has evolved into an effective and safe treatment modality for both primary[1] and secondary[2] pulmonary malignancies
The inclusion criteria for cases eligible for this analysis were: (1) thoracic malignancy treated with stereotactic body radiotherapy (SBRT) in the past, (2) with a recurrence or second primary tumor with any distinct anatomic overlap of the initial primary target volumes (PTV) after rigid registration, (3) recurrence treated with a second course of SBRT, (4) where both SBRT-courses had to fulfill the criteria as defined SBRT by the DEGRO-group (a.o. ≤ 12 fractions, BED10 ≥ 50 Gy)[15], (5) where the treatment plans and dosimetric parameters of both SBRT-courses are available in Digital Imaging and Communications in Medicine (DICOM) standard format
We evaluated a total of 27 patients who fulfilled the study inclusion criteria, treated from 2009 to 2020

Summary

Introduction

Stereotactic body radiotherapy (SBRT) has evolved into an effective and safe treatment modality for both primary[1] and secondary[2] pulmonary malignancies. These studies could demonstrate that re-irradiation can be a reasonable option for palliation and that SBRT could serve as a relatively effective salvage treatment after failure of normofractionated regimens[9,10,11], some authors observed excessive toxicity[12]. Recent publications investigated the application of repetitive SBRT-courses for lung malignancies, but all of these series used different definitions of re-irradiation and underlie several limitations[13,14] Aim of this multicentre retrospective study is to provide a comprehensive analysis of patterns of care, feasibility, safety and technical features of a second in-field SBRT course. Accumulated dose distributions of the first and second SBRT-course formed the basis for the analysis of dosimetric factors impacting safety and efficacy

Methods

Results

Conclusion