Supplementary Material for: Long-term survival following trimodal therapy including hyperfractionated radiotherapy in parotid NUT carcinoma: A 29-month follow-up case report

Introduction: NUT carcinoma (NC) is a rare, aggressive malignancy with median survival below one year. Reports of long-term survival are exceptional and rare. While multimodal treatment strategies including surgery, radiotherapy, and chemotherapy have been attempted, evidence remains scarce. Case Presentation: We report the case of a middle-aged female patient with parotid NC harboring a NSD3::NUTM1 fusion. Following surgical resection, rapid disease progression with newly evident lymph node metastases occurred within three weeks, prompting definitive hyperfractionated intensity-modulated radiotherapy using a simultaneous integrated boost (SIB) technique (1.4 Gy/1.6 Gy to 56.0 Gy/64 Gy, twice daily, 40 fractions) with concurrent weekly cisplatin (50 mg/m²). Acute toxicities were limited to grade 2 mucositis and dermatitis; no severe late effects were observed. At 29 month follow-up, the patient remains disease-free, with preserved quality of life. This case adds to the limited body of literature documenting long-term survival in NC, parotid localisation is rare and hyperfractionated radiotherapy is not reported yet. Durable remission has only been reported in isolated cases and often with significant treatment-related morbidity. Comparison with previously published cases suggests that multimodal strategies, when feasible, may provide a chance for long-term survival, although optimal regimens remain undefined. Conclusion: The present case suggests that hyperfractionated radiotherapy, exploiting radiobiological advantages in rapidly proliferating tumors, may improve both tumor control and toxicity profile compared to conventional fractionation in NC, warranting further investigation. To our knowledge, this represents one of very few reports of a parotid NC patient achieving disease-free survival beyond two years after trimodal therapy.