S584
Clinical – Head & neck
ESTRO 2026
Material/Methods: We conducted a single-center, prospective cohort study on patients with non-metastatic recurrent or second primary head and neck SCC within a previously irradiated area. Eligibility criteria required that prior radiotherapy had been completed at least six months earlier. Patients should be suitable candidates for re- irradiation based on their initial treatment response and complications. The multimodal strategy encouraged surgical resection before re-irradiation when technically and functionally feasible. Our protocol permitted systemic therapy including induction, concurrent, or consolidation chemo-, bio-, or immunotherapy. Re-irradiation was delivered using advanced techniques, specifically intensity-modulated radiotherapy IMRT or VMAT using modern LINACs. Acute and late toxicities were assessed according to CTCAE criteria during treatment and at the three- month follow-ups, followed by an imaging-based evaluation of tumor response. Results: Twenty-two patients met the eligibility criteria. Of these, 19 (mean age 62.1 ± 10 years) proceeded with re-irradiation, while three did not initiate treatment for various reasons. Two patients presented with second primary head and neck SCC, whereas the remainder exhibited locoregional recurrences. The predominant re-irradiation technique was VMAT, with a median dose of 60 Gy. At the time of data analysis, six patients were still undergoing active treatment or surveillance. Consequently, the present analysis was made on 13 patients who had completed the re-irradiation course. One year post-treatment, local control was achieved in 77% (10/13), who demonstrated either stable disease or a partial response. The median overall survival following re-irradiation was 8.9 months (95%CI: 4.5- 13.3 months), and 1-year overall survival is 35% (Figure 1).
2b).
Conclusion: Re-irradiation by advanced techniques is a valid option for recurrent or second primary HNSCC, offering promising 1-year local control and survival with generally manageable low-grade toxicity. Nevertheless, careful patient selection, precise treatment planning, and close follow-up are essential to minimize the risk of severe late complications. A longer follow-up is needed to confirm late oncological outcomes. Keywords: Re-irradiation, Head and Neck SCC, Recurrence Digital Poster 2065 A Comparative Study of Multiple Atlas-based and Manual Contouring for Organs at Risk in Nasopharyngeal Radiotherapy Teeradon Treechairrusame, Chidchanok Wisuthwatcharakul, Kullathorn Thephamongkhol, Kanokkarn Kuekkong, Pongpop Tuntapakul, Tanwiwat Jaikuna Radiology, Siriraj Hospital, Bangkok, Thailand Purpose/Objective: Atlas-based auto-segmentation (ABAS) can reduce the time for organs at risk (OARs) contouring and variability in the inter-observers. This study investigates the performance of multiple commercial ABAS software for OARs segmentation in nasopharyngeal cancer. Material/Methods: Radiotherapy data from 110 nasopharyngeal cancer patients between 2016-2020 were arbitrarily included. A total of 100 patients were stratified as a normal distribution clustering into subgroups of 20, 40, 60, 80, and 100 patients using the K-means method by considering T, N, and BMI factors that might interfere with OARs’ shape and volume. The centroid patient of each cluster was selected for atlas library generation on RayStation v.10.1, MIM v.7.0, and Velocity v.4.1. The performance of ABAS was evaluated in 10 validation patients by considering the geometrical accuracy using Dice similarity coefficient (DSC), Mean distance to agreement (MDA), and Hausdorff distance (HD) of 26 OARs contours between ABAS generation and manual contouring.The elapsed time after modification and
Among the 6 deaths, three died of locoregional progression, while the other three died of distant metastatic disease. Acute toxicities were predominantly Grade 1-2 and clinically manageable (Figure 2a). The most common late complications were fibrosis, dysphagia, and pain, each occurring in 11 (84.6%) patients with mostly grade 1-2. Notably, two severe and life-threatening late toxicities, including carotid blowout syndrome and dysphagia, were reported (Figure
Made with FlippingBook - Share PDF online