ESTRO 2025 - Abstract Book

S309

Brachytherapy – Head & neck, skin, eye

ESTRO 2025

Purpose/Objective: Brachytherapy for lip cancer can be an organ preservation treatment with similar results as surgery but improved cosmetic/functionality. In this study we aim to evaluate the outcomes of patients treated with interstitial High Dose Rate (HDR) Brachytherapy for lip cancer in our center, as well as explore prognostic factors influencing local control. Material/Methods: Retrospective single center cohort study of 104 patients affected with T1-T3 squamous cell carcinoma of the lip, from 2010 to 2023. All patients were treated with interstitial HDR brachytherapy with rigid needles or plastic tubes, twice a day for 5 working days. Treatment intention could be radical, adjuvant, or as a rescue after relapse. Clinical and treatment data, as well as late toxicity (>1 year), were collected. Survival estimates were calculated using Kaplan-Meier, and univariate/multivariate analysis (UVA/MVA) was performed using Cox regression.

Results: Patient and treatment characteristics are summarized in Table 1. Median age at diagnosis was 77 years [Interquartile Range (IQR) 70-84 years].

Implant with rigid needles was used in 75 patients (72.1%) and plastic tubes in 29 (27.9%). Median number of vectors was 3 (min-max 2-13). For radical and rescue treatment, all patients but one received a total dose of 50Gy with 5Gy/fr. For adjuvant cases, median total dose was 45Gy (min-max 40.5-50Gy), with median dose/fraction of 4.5Gy (min-max 4.5-5Gy).

Two patients (1.92%) developed late skin toxicity G3, and 1 patient presented radionecrosis. Telangiectasias were present in 36 patients (34%) and skin marks in 15 patients (14.42%).

With a median follow up of 41 months (IQR 16.5-98.75 months), 3-year Overall Survival, Cancer Specific Survival, and Local Control (LC) were 75.9% (CI95% 67.28-84.52), 95.7% (CI95% 91.58-99.82), and 90.6% (CI95% 84.72-96.48), respectively. Regional and Systemic relapse free survival at 3 years was 90.6% (CI95% 84.72-96.48) and 99% (CI95% 97.04-100).

In UVA, only the T stage (p=0.012) and the number of vectors (p=0.028) were related to LC. When performing MVA, T3 stage alone (HR 10.08, CI95% 1.64-62.05) remained as a predictor for worse LC (Table 2).