S384
Clinical - CNS
ESTRO 2026
Digital Poster 3834
adjuvant therapy according to the Stupp protocol. Data were collected on patient, tumour, and treatment variables. Operative records were reviewed to classify 5-ALA residual pattern as: no residue (no visible 5-ALA at the end of resection), focal residue (5-ALA–positive tissue remaining involving 1–2 walls), or diffuse residue (involvement of more than 2 walls). Dates of relapse and death were recorded to calculate progression-free survival (PFS) and overall survival (OS). Statistical analysis used SPSS v29. Kaplan–Meier curves and log-rank tests compared survival between groups. Results: Forty-six eligible patients were identified. Median age was 55 years (range 31–70); most were male (n = 31). No residual 5-ALA was observed in 23 patients, focal in 18, and diffuse in 5. There was a moderate correlation between 5-ALA residual pattern and extent of resection (f = 0.414, p = 0.004), with a high positive predictive value (85.4%) but lower negative predictive value (60%). Grouping no or focal residual versus diffuse residual pattern predicted OS (16.1 vs 9.3 months, p = 0.024) and PFS (10.9 vs 4.5 months, p = 0.004). The adverse effect on OS persisted after stratifying by age (<65 vs ≥ 65, p = 0.011) and MGMT methylation status (methylated vs unmethylated, p = 0.013). Cox regression identified unmethylated MGMT (p < 0.01) and longer interval from surgery to radiotherapy (p = 0.002) as negative predictors of OS. No significant differences were found between no residual and focal residual groups for OS (p = 0.696) or PFS (p = 0.667). Conclusion: Diffuse pattern of 5-ALA residual fluorescence is associated with worse oncological outcomes after 5- ALA–guided maximal safe resection followed by standard adjuvant therapy, independent of age and MGMT status. Focal 5-ALA residue was not detrimental to patient outcomes when compared to the no residue group which could aid intra-operative decisions on resection extent in eloquent locations.* - Joint authors References: 1. Stummer W, Pichlmeier U, Meinel T, Wiestler OD, Zanella F, Reulen HJ. Fluorescence-guided surgery with 5-aminolevulinic acid for resection of malignant glioma: a randomised controlled multicentre phase III trial. Lancet Oncol 2006; 7(5): 392-401.2. Baig Mirza A, Christodoulides I, Lavrador JP, Giamouriadis A, Vastani A, Boardman T, et al. 5-Aminolevulinic acid-guided resection improves the overall survival of patients with glioblastoma-a comparative cohort study of 343 patients. Neurooncol Adv 2021; 3(1): vdab047. Keywords: Glioblastoma Multiforme, 5-Aminolevulinic Acid
Proton radiotherapy for recurrent or residual pituitary adenoma: A retrospective, single center experience. Fabian Allmendinger, Maximilian Deng, Sebastian Regnery, Lars Wessel, Felix Englert, Ricarda Wickert, Jannik Walter, Lucas Mose, Paul Wacker, Jürgen Debus, Laila König, Tanja Eichkorn Department of Radiation Oncology, Heidelberg University Hospital, Heidelberg, Germany Purpose/Objective: Although benign, pituitary adenomas (PA) impair neurological and endocrine function. Hence, observation alone is often insufficient and initial surgery commonly required. For recurrent or residual PA, proton radiotherapy (PRT) is presumed to offer superior additive or salvage treatment in the vulnerable sellar region due to the tissue-sparing characteristics of the Bragg-peak effect and particularly when compared with repeat surgery or conventional photon radiotherapy. However, the evidence remains limited, and treatment selection often depends on institutional expertise and available technology, underscoring the need for systematic evaluations to integrate PRT into evidence-based decision-making. Material/Methods: Single center, retrospective experience revisiting 97 patient records treated with PRT in a salvage setting and 24 records treated with PRT as an additive modality following initial resection for residual adenoma. The primary study outcome was overall tumor control. Secondary outcomes included treatment toxicity, hormonal control rates and improvement in visual function. Results: We observed excellent 5-year overall tumor control rates of 93.5% in the salvage cohort and 100.0% in the additive PRT cohort. In the salvage group, the median interval between initial surgery and PRT was 25 months. No grade 3 or 4 toxicities were observed. The most frequently reported adverse events were headache (42%) and fatigue (57%). Two patients developed a secondary malignancy that was considered potentially attributable to PRT. Improvement in visual function was achieved in 77% of patients, and hormonal control (with or without medication) was reached in 71%. In the additive cohort no grade 4 toxicity was observed. Visual improvement occurred in 67% of patients, and hormonal control (with or without medication) was achieved in 96%. Conclusion: We highlight proton radiotherapy as an effective and safe treatment option for recurrent or residual pituitary adenoma, with favorable hormonal control
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