3D-printing non-co-planar template-assisted computed tomography-guided I-125 seed interstitial brachytherapy for recurrent head and neck squamous cell carcinomas after external beam radiotherapy: Preliminary one-arm study

Abstract

We report and review herein the preliminary results of recurrent head and neck squamous cell carcinoma (HNSCC) treated with 3D-printing non-co-planar template (3D-PNCT)-assisted CT-guided radioactive I-125 seed (RIS) interstitial brachytherapy after external beam radiotherapy (EBRT), as a salvage modality to analyze the feasibility, efficacy, and safety of this treatment. Forty-two patients with recurrent HNSCC after EBRT were enrolled from April 2016 to June 2018 in Peking University 3rdHospital. The KPS scores ranged from 60 to 90 (median, 80). The prescribed doses were 100–180 Gy. The activity of a single I-125 seed was 0.35–0.73 mCi (median, 0.55). The RIS interstitial brachytherapy work-flow included patient set-up, CT simulator scan contrast with 5-mm thickness, drawing of target region and defined prescription doses, designed needles arrangement, direction, depth and angles, sending images to 3D-printer for printing individual template, patients re-set-up, 3D-PNCT stabilization, puncture implant needles, CT-scans again for intra-operation dose optimization. The position of all needles was minimally adjusted and matched completely with the pre-plan, the seeds then implanted, and finally the post-doses were evaluated. The short-term efficacy was evaluated by RECIST v1.1, and adverse events were evaluated by CTCAE V4.0. The patients were followed up for 3 to 32 (median, 9) months. The lesion volume nagged from 1.6 to 91.4 (median, 22.7) cm3. The D90 of post-plan ranged from 92.8 to 194 (median, 153.5) Gy. The 1-year and 2-year local control rates were 70.1% and 54.1%, respectively. The median overall survival was 16 months, with the 1-year and 2-year estimates of overall survival being 54.6% and 47.8%, respectively. Univariate analysis showed age, implantation site, D90, short-term efficacy, and previous surgery correlated with local control rate. The 1- and 2-year local control rates were 81.3% and 56.9% if D90 >130 Gy, and were 33.3% and 33.3% if D90 ≤130 Gy, respectively (P=0.024). Lesion volume, time from EBRT to seed implantation, and short-term efficacy were correlated with survival. Multivariate analysis showed that short-term efficacy and previous surgery were independent factors for local control (P=0.003 and 0.041). Age, lesion volume, and time from radiotherapy to seed implantation were independent factors associated with survival (P=0.019, 0.013, and 0.001). With regard to adverse effects, 14 patients had skin/mucosa ulceration (33.3%), 6 cases of pain (14.3%), one had osteonecrosis of the jaw (2.4%), and one had carotid blowout (2.4%). The correlation between toxicity and dose has not been found. 3D-PNCT-assisted CT-guided RIS interstitial brachytherapy is feasible, effective, and a safe salvage modality for patients with recurrent HNSCCs. High dose (D90>130 Gy), favorable short-term efficacy (CR/PR), and no-previous surgery were correlated with better local control.