Outcomes with multi-disciplinary management of central lung tumors with CT-guided percutaneous high dose rate brachyablation

Abstract

Background: Centrally located lung tumors present treatment challenges given their proximity to mediastinal structures including the central airway, esophagus, major vessels, and heart. Therapeutic options can be limited for medically inoperable patients, particularly if they have received previous thoracic radiotherapy. High dose rate (HDR) brachyablation was developed to improve the therapeutic ratio for patients with central lung tumors. The purpose of this study is to report initial safety and efficacy outcomes with this treatment for central lung malignancies.

Methods: From September 2015 to August 2019, a total of 25 patients with 37 pulmonary tumors were treated with percutaneous HDR brachyablation. Treatment was delivered by a multi-disciplinary team of interventional radiologists, pulmonologists, and radiation oncologists. Twenty-three patients received a median dose of 21.5 Gy (range 15-27.5) in a single fraction, whereas two patients received median dose of 24.75 Gy (range 24-25.5) over 2-3 fractions. Tumor local control (LC) was evaluated by Response Evaluation Criteria in Solid Tumors v1.1. Treatment-related toxicities were graded by Common Terminology Criteria for Adverse Events v5.0, with adverse events less than 90 days defined as acute, and those occurring later were defined as late. LC, progression-free survival (PFS), and overall survival (OS) rates were estimated by the Kaplan-Meier method.

Results: Of 37 treated tumors, 88% were metastatic. Tumor location was central and ultra-central in 24.3% and 54.1%, respectively. Average tumor volume was 11.6 cm³ (SD 12.4, range 0.57-62.8). Median follow-up was 19 months (range 3-48). Two-year LC, PFS, and OS were 96.2%, 29.7%, and 65.5%, respectively. Thirteen of 39 (33.3%) catheter implantation procedures were associated with trace minor pneumothorax requiring no intervention, 1 (2.5%) procedure with minor radiographic pulmonary hemorrhage, and 4 (10.3%) with major pneumothorax requiring chest tube insertions. All procedural complications resolved within 24 h from treatment. Acute grade 1-2 toxicity was identified in 4 patients, whereas none developed late toxicity beyond 90 days of follow-up.

Conclusion: Percutaneous HDR brachyablation is a safe and promising treatment option for centrally located primary and metastatic lung tumors. Future comparisons with stereotactic body radiotherapy and other ablative techniques are warranted to expand multi-disciplinary management options.

Keywords: Brachyablation; Brachytherapy; High-dose-rate brachytherapy; Interstitial brachytherapy; Pulmonary metastasis.

Fig. 1

A 60-year old man with metastatic leiomyosarcoma presenting with multiple lung metastasis. He had undergone multiple microwave ablations for other lung tumors. A malignant left sub-hilar lymph node continued to grow despite treatment with multiple cycles of doxorubicin and olaratumab. This tumor was treated with CT-guided interstitial HDR brachyablation. A Placement of co-axial needle under CT-guidance during brachytherapy catheter implantation. A co-axial needle was advanced percutaneously and placed directly into the ultra-central tumor abutting the heart. B Axial C Sagittal and D Coronal views of resultant treatment isodose distribution

Fig. 2

Kaplan–Meier curve for local control

Fig. 3

A Kaplan–Meier curve for progression free survival. B Kaplan–Meier curve for overall survival