Tailored contact brachytherapy for challenging facial basal cell carcinomas: clinical results of 3D printing technology implementation

Background: Basal cell carcinoma (BCC) often arises on cosmetically and functionally sensitive facial sites where standard contact brachytherapy applicators may not conform optimally. Patient-specific, 3D-printed surface applicators may improve geometric conformity, reduce air gaps, and enhance dose reproducibility. We report outcomes of individualized 3D-printed contact high-dose-rate brachytherapy (HDR-BT) for challenging facial BCC. Materials and methods: In this single-institution retrospective study, patients with histologically confirmed facial BCC in curved or irregular sites were treated with customized 3D-printed surface applicators. A planning computed tomography (CT) obtained with the applicator in situ guided contouring and optimization. Treatment was delivered with an Ir-192 HDR afterloader to 42–45 Gy in 6–11 fractions. Patients were evaluated at 4 weeks and then every 3–6 months. Primary endpoints were complete response (CR) and local control (LC); toxicity was graded per Radiation Therapy Oncology Group/European Organisation for Research and Treatment of Cancer (RTOG/EORTC) scale. Results: Twenty-six patients (31 lesions; median age 77 years) were treated: T1 77%, T2 13%, T3 10%. Sites: nose 81%, peri-orbital 13%, ear 6%; 58% primary, 42% postoperative recurrences. At a median follow-up of 32 months, CR and LC were 100%. Acute reactions were mainly grade 1–2 skin changes; higher-grade events were transient. Late toxicity comprised grade 1 discoloration/hypopigmentation in 52% and grade 2 telangiectasia in 23%; 25% had no late toxicity. No grade ≥ 3 late events occurred. Conclusions: Individualized 3D-printed contact applicators yielded excellent tumor control with low late toxicity in complex facial BCC. These practice-oriented data support wider implementation of personalized applicators in surface HDR-BT and encourage prospective validation in multicenter settings.