ESTRO 2025 - Abstract Book

S1062

Clinical – Head & neck

ESTRO 2025

Purpose/Objective: Palliative hypofractionation schedules to high doses with few fractions per week have often been employed for squamous cell head and neck cancer (HNSCC), aimed at controlling disease and preventing or alleviating severe, often life-threatening symptoms. Also, elderly frail patients with comorbidities, and expected low compliance to standard radiotherapy, may benefit from such schedules. In Denmark, 52-56 Gy in 13-14 fractions given in 6½ weeks has widely been used, and a nationwide, retrospective study was performed by DAHANCA to describe treatment outcome and to explore benefits and side effects. Material/Methods: Demographics and treatment data was retrieved from the DAHANCA database of patients with HNSCC of the pharynx, oral cavity, and larynx (n = 949) undergoing primary treatment. Inclusion was prescribed dose 52-56 Gy between 2007-2022 in a hypofractionated schedule of 4 Gy per fx biweekly. Five patients were excluded, leaving 944 for analysis. A clinical assessment was scheduled 8 weeks after treatment for evaluation of response and toxicities. Results: The median age was 71 years (57-99) and 74% had a WHO Performance Status ≥2. Primary tumor site was oropharynx 59%, larynx 21%, and oral cavity 19%. Distant metastatic disease was observed in 14%, and 85% had St. III-IV disease. In total, 89% complied to the prescribed dose of 52-56 Gy/13-14 fx, which was given in 42 days (median). End-of treatment tumor response could be evaluated in 538 subjects (57%). Progressive Disease was noted in 13 (2.4%), No Change in 43 (8.0%), Partial Remission in 127 (23.6%), and Complete Remission in 355 (66%), i.e., 89.6% of evaluable patients experienced tumor reduction. Confluent mucositis (Grade ≥3) was recorded with a peak of 14.4% at the end of RT. Overall, 879 patients had died (93%). Within 100 days from start of RT, 17% had died, which on multivariable logistic regression analysis was significantly related to disease stage (p=0.023) and performance status (p=0.028). The 2 year cause-specific survival and overall survival (OS) rates were 31.4% (28.3-34.5) and 21.9% (95% CI: 19.2-24.6), respectively, with a median OS of 10.4 months. Conclusion: Palliative high-dose radiotherapy with 2 x 4 Gy per week demonstrated high response rates and low grades of mucositis in HNSCC with a curative potential in a subgroup of patients. However, due to poor performance status and advanced disease in general, the overall survival rate of the cohort was low. Patients not likely to benefit from standard RT schedules should be identified and offered alternative short treatment schedules.

Keywords: Palliation, hypofractionation, survival

3069

Digital Poster Adjuvant radiotherapy for pleomorphic dermal sarcoma of the head and neck Matthew R. Fahy, Jake F. Murphy, Sinéad Brennan Radiation Oncology, St. Luke's Radiation Oncology Network, Dublin, Ireland

Purpose/Objective: Pleomorphic dermal sarcoma (PDS) is a rare cutaneous malignancy with an overwhelming male preponderance and found in sun-exposed areas most commonly on the scalp (1). It is differentiated from its associated condition, atypical fibroxanthoma, by the presence of necrosis, perineural or vascular invasion and deep invasion of the subcutis (1,2). Given its rising incidence and adverse biology, and with local recurrence rates as high as 28% reported, adjuvant radiotherapy is often considered(2,3). However, there are no guidelines regarding appropriate selection of patients for adjuvant radiotherapy, target volume definition or dose response data for PDS. Our