ESTRO 2025 - Abstract Book

S1714

Clinical - Sarcoma & skin cancer & malignant melanoma

ESTRO 2025

influencing long-term disease control—such as dose fractionation and biological equivalency (EQ2)—require further study. This research evaluates the efficacy of superficial RT for radical treatment of BCC and examines the impact of EQ2 doses on recurrence rates, providing insights into optimizing treatment protocols. Material/Methods: This retrospective study analyzed patients diagnosed with BCC who received superficial RT with curative intent between 2017 and 2019. Demographic and oncological variables, including sex, age, lesion size, anatomical site, and treatment parameters, were collected. Fractionation schedules were converted to EQ2, ranging from 50 Gy to 116.67 Gy. Statistical analysis was performed using Jamovi V.2.3.28, considering p < 0.05 as statistically significant. Results: A total of 345 patients were included, 167 women and 177 men, with a mean age of 82.7 years. 159 lesions were biopsied prior to treatment. The most commonly treated anatomical sites were the nose (108 patients, 31%) and the temple (31 patients, 8.9%). The median tumor diameter was 2 cm, and most patients were treated for a single lesión. Superficial RT was predominantly delivered energy of 80 kV. The most commonly used fractionation scheme was 50 Gy, 5 Gy per session, 2 sessions per week (17.6%). EQ2 doses ranged from 50 Gy to 116.67 Gy, tailored to lesion size, location, and patient-specific factors. After a mean follow-up of 45.9 months, 281 patients achieved complete disease control, while 48 patients (13.9%) experienced recurrence at a mean of 31 months post-treatment. Statistical analysis showed no significant association between EQ2 doses and recurrence rates (p = 0.692). Conclusion: S uperficial RT is a highly effective, non-invasive and versatile treatment for BCC, offering excellent disease control and cosmetic outcomes, particularly in elderly and high-risk patients. Although no significant association was found between EQ2 doses and recurrence rates, these findings underscore the importance of further investigating patient specific and tumor-specific factors, as well as conducting future research and long-term follow-up to refine treatment protocols, improve therapeutic outcomes, and ensure a personalized and optimized approach for patients with BCC.

Keywords: Superficial radiotherapy, BCC, Recurrence.

3640

Digital Poster Tomotherapy for in-transit or metastatic lower limb melanoma.

Joaquín Velasco-Jiménez 1,2 , Lourdes Gutiérrez-Sanz 3 , Marta López Valcárcel 1 , Sara Pérez-Mata 1 , Beatriz Gil-Haro 1 , Raquel Benlloch Rodríguez Benlloch-Rodríguez 1 , María Hernández-Miguel 1 , Sofía Santana-Jiménez 1 , Sofía Merino Pedraza 1 , Jesús Romero Fernández 1 1 Radiation Oncology, Hospital Universitario Puerta de Hierro majadahonda, Majadahonda, Spain. 2 Odontology, Universidad CEU San Pablo, Madrid, Spain. 3 Medical Oncology, Hospital Universitario Puerta de Hierro Majadahonda, Majadahonda, Spain Purpose/Objective: In-transit metastases (ITM) of melanoma are locoregional recurrences confined to superficial lymphatics. Occurrence is 3.4–6.2%. Disproportionately in lower limbs due to gravity and greater lymphatic network. We present a retrospective review of an innovative technique. Material/Methods: Six consecutive patients treated between April 2011-April 2022 with tomotherapy using hypofractionated regimen of 30 Gy in 6 fractions at 2 fractions/week over 3 weeks. First patient received 3 x 8 Gy and one patient an integrated boost (SIB) to the macroscopic lesions 5 x 7 Gy with concomitant Nivolumab. PTV30 was defined as all GTV including the primary and superficial lymphatics up to the proximal lesion leaving a corridor with at least a