Template-assisted ¹⁹²Ir-based stereotactic ablative brachytherapy as a neoadjuvant treatment for operable peripheral non-small cell lung cancer: a phase I clinical trial

Purpose
To evaluate safety, feasibility, and efficacy of template-assisted ¹⁹²Ir-based stereotactic ablative brachytherapy (SABT), combined with surgery for peripheral non-small cell lung cancer (NSCLC).

Material and methods
Patients with pathologically confirmed operable peripheral NSCLC, who underwent template-assisted SABT (30 Gy delivered in one fraction) and were scheduled for tumor resection 4-6 weeks after SABT were included in this study. The perioperative adverse reactions of SABT were recorded to evaluate safety and feasibility of SABT for neoadjuvant therapy. Dosimetric data from both simulated and actual plans were collected and compared. Imaging with ¹⁸F-fluorodeoxyglucose-positron emission tomography/computed tomography (¹⁸F-FDG-PET/CT) and dynamic contrast-enhanced computed tomography were scheduled before SABT and surgery to evaluate the efficacy of the neoadjuvant therapy with SABT.

Results
Patients did not experience any serious adverse events. None of the patients had a delay in receiving surgery. After 4-6 weeks, the indicators for the efficacy of neoadjuvant therapy significantly decreased in all patients: gross tumor volume (p < 0.001), maximum standardized uptake value (p < 0.001), tumor blood volume (p < 0.001), and tumor blood flow (p = 0.008). Dosimetric parameters in the delivered SABT plan slightly changed from the preoperative simulation, but the difference was not statistically significant (p > 0.05).

Conclusions
The efficacy of template-assisted SABT for neoadjuvant therapy was significant in operable peripheral NSCLC. Moreover, no serious adverse reactions were observed; when the coplanar template guidance technique was applied, dosimetric parameters were in good agreement between the actual SABT plan and the preoperative simulated plan.