Ömer Erol Uzel

Objective: While advancements in radiotherapy and systemic agents have significantly improved survival rates in head and neck squamous cell carcinoma (HNSCC), managing long-term, treatment-induced toxicities remains a critical clinical challenge. This study aimed to develop a personalized, supervised machine learning-driven predictive model for multiple chronic toxicities by integrating clinical, dosimetric, and genetic data specifically evaluating the impact of the NBN gene rs1805794 (c.553G>C) polymorphism. Methods: This study enrolled 125 patients with HNSCC who received curative-intent radiotherapy and remained disease-free during follow-up with a median of 98 months. Comprehensive clinical and dosimetric data were collected, and chronic toxicities were recorded. Peripheral blood samples were analyzed for the NBN rs1805794 polymorphism using allele-specific PCR (AS-PCR). Following feature selection, four supervised machine learning classifiers were trained and evaluated to identify the optimal model for predicting multiple chronic toxicities. Results: The XGBoost algorithm emerged as the highest performing model. Baseline clinico-dosimetric predictors of multiple chronic toxicities included PTV70 volume, the addition of concurrent chemotherapy, advanced T and N stages, and continued smoking. Integrating the NBN rs1805794 genotype into the XGBoost architecture enhances its predictive capability. The final model accurately identified patients at high risk for multiple chronic toxicities, achieving an area under the curve (AUC) of 0.78, an accuracy of 0.77, a sensitivity of 0.74, and a specificity of 0.79. Conclusions: Integrating clinical, dosimetric, and genetic data within a machine learning framework effectively predicts multiple chronic toxicities in HNSCC. This approach enabled early risk stratification, providing the potential for personalized therapy.

Background/Objectives: Head and neck paragangliomas (HNPGs) are rare, typically benign, hypervascular tumors arising from neural crest cells. Although surgery is known as the primary treatment, radiotherapy (RT) is preferred for large and inoperable tumors. This study evaluated the results and safety of RT. Methods: Fifteen patients with radiologically or histologically confirmed HNPG treated with RT between 2001 and 2024 were retrospectively analyzed. Most patients received intensity-modulated radiotherapy (IMRT) with a median dose of 45 Gy. Treatment-related toxicities were graded according to CTCAE criteria. Local control (LC) was estimated with using Wilson score method. Results: With a median follow-up of 96 months, all patients achieved stable or improved symptomes, without local recurrence, resulting in a 100% LC rate. RT was well tolerated, with no acute or late toxicities ≥ grade 2. Conclusions: RT, particularly IMRT, provides excellent long-term LC with minimal toxicity in patients with HNPG. RT represents an effective and well-tolerated treatment option, especially for patients with unresectable disease or high surgical risk.

Purpose This study evaluated survival outcomes and chronic side effects in adult medulloblastoma patients treated with craniospinal irradiation (CSI). Methods We performed a retrospective analysis of 30 adult medulloblastoma patients treated with postoperative craniospinal radiotherapy (RT; 30–36 Gy) combined with a posterior fossa/tumor bed boost (54 Gy). Kaplan–Meier methods were used to analyze local control (LC) and survival. Long-term quality of life was assessed using the 12-Item Short Form Health Survey (SF-12) questionnaire and the telephone cognitive evaluation (T-Cog) test. Results With a median follow-up of 87 months, 10 patients (33.3%) died, 6 due to craniospinal fluid (CSF) recurrence and 4 from distant metastases. The 5‑year local control (LC) and overall survival (OS) rates were 85% and 71%, respectively. Alopecia (64.7%), cognitive decline (41.1%), and ototoxicity (41.1%) were common long-term toxicities, with 5 of 7 ototoxicity cases linked to cisplatin. Secondary tumors occurred in 2 patients. Cognitive impairment was indicated by a mean T‑Cog score of 24, while SF-12 physical and mental health scores were 47.8 and 44.4, both below the cutoff of 50. Conclusion Craniospinal RT is a safe and effective treatment for adult patients with medulloblastoma. Future treatment strategies should aim to deintensify therapy by limiting radiation to the local tumor bed in selected low-risk patients and by identifying favorable molecular subgroups for observation after surgery. Advanced techniques and targeted therapies can further reduce toxicity while maintaining strong oncologic outcomes and enhancing quality of life.

Radyoterapide hasta uygulamalarında ‘bolus’ olarak isimlendirilen doku eşdeğeri malzemeler ya da hasta tedavileri öncesi cihaz kalibrasyonunda doku eşdeğeri fantomlar kullanılmaktadır. Ancak ticari olarak satılan bu malzemeler standart boyutlarda üretilerek satışı yapılmakta; farklı dizaynlara duyulan ihtiyacı karşılamamaktadır. Son yıllarda farklı dizaynlarda üretim ihtiyacını karşılamada 3 boyutlu (3B) yazıcılar önemli bir rol üstlenmektedir. Bu çalışmada kullanımı giderek artan 3B yazıcılarda kullanım için üretilmiş PLA (Poliaktik Asit), TPU (Termoplastik Poliüretan) ve Naylon (Polyamide) malzemelerinin radyasyona verdikleri cevabın dozimetrik olarak değerlendirilmesi hedeflenmiştir. BT simülatör cihazında Hounsfiel Unit (HU) değerleri belirlendi. Dozimetrik ölçümler Varian DHX lineer hızlandırıcısında elde edilen 6 MV nominal foton enerjisi kullanılarak yapılmıştır. Yüzde derin doz (%DD) ve doz profili ölçümleri su fantomunda, ışın geçirgenlik ölçümleri katı fantomda yapılmıştır. Malzemelerin ortalama HU yoğunlukları -8.61 ile -441.08 arasında değişmektedir. PLA malzemesi ort. -24.72 ile suyun HU değeri (0)’ ne en yakın sonuçları vermiştir. % derin doz ve penumbra değerleri %2 ve ±2 mm içerisinde bulunmuştur. Tüm malzemelere ait geçirgenlik ölçümleri değerlendirildiğinde RW3 katı su fantomu plakası ile değişimin maksimum % 0.2 olduğu görülmüştür. 3B yazıcıda basılan malzemelerin dozimetrik parametrelerinin birbirlerine benzer sonuçlar verdiği ancak hastada kişisel malzeme olarak kullanılmadan önce basım özellikleri ve malzeme değişkenlikleri sebebiyle kullanılacak malzemenin dozimetrik olarak değerlendirilmesi uygun gözükmektedir.

Background The mainstay treatment of nasopharyngeal cancer (NPC) is radiation therapy (RT). The doses and volumes may differ from center to center. Most studies and guidelines recommend a total dose of 60 Gy for elective nodal and peritumoral volume treatment. This retrospective analysis aimed to analyze whether a dose reduction to 54 Gy to this volume would be associated with a higher risk of recurrence. Methods A total of 111 patients treated by intensity-modulated radiotherapy (IMRT) and concurrent chemotherapy were retrospectively analyzed. The recurrent tumor volume was classified as “in field” if 95% of the recurrent volume was inside the 95% isodose, as “marginal” if 20–95% of the recurrence was inside the 95% isodose, or as “outside” if less than 20% of the recurrence was inside the 95% isodose. Results Median follow-up was 67 months (range 6–142). The 2‑ and 5‑year overall survival (OS) rates were 88.6% and 70%, respectively. The 2‑year locoregional control (LRC), disease-free survival (DFS), and distant metastasis-free survival (DMFS) were 93.3%, 89.3%, and 87.4%, and the 5‑year LRC, DFS, and DMFS were 86.8%, 74%, and 81.1%, respectively. Ten patients (9%) had a local and or regional recurrence. Half of the patients with locoregional failure had in-field recurrences. For primary tumor, there was no recurrence in the volume of 54 Gy. For regional lymph node volume, recurrence was detected in two (1.8%) patients in the volume of 54 Gy. Conclusion These retrospective data suggest that a dose reduction may be possible for intermediate-risk volumes, especially for the primary site.

Purpose We aimed to investigate the appropriate postoperative radiotherapy dose and selective volume in T3–4 N0 laryngeal cancer patients treated with either total or partial laryngectomy. Methods Patients who received radiotherapy for locally advanced (T3–T4) and pathologic node-negative (N0) squamous cell laryngeal cancer were retrospectively evaluated. Radiotherapy was applied to median 60 Gy (range 54–60 Gy) as selective local radiotherapy (±stoma). The local treatment areas included postoperative bed + laryngeal area for patients with a partial laryngectomy, and the postoperative bed only for patients with total laryngectomy. Results The median follow-up time was 59 months and 52 patients were included. The 2‑year, 5‑year, and 8‑year locoregional recurrence controls (LRC) were 95.6%. The 2‑year and 5‑year OS rates were 93.8% and 78.9%, respectively. The 5‑year OS for age < 60 years was 95.8%, for above 60 years 56.5%. Conclusion Our data suggest that local selective irradiation to the postoperative bed + stoma is enough in patients with T3–4 N0 laryngeal cancer without applying elective nodal irradiation.

Objective: In the current classification of brain tumors of the World Health Organization, various tumor histologies have been categorized under the main heading of glial tumors. The subgroup of low-grade gliomas comprises grade 2 diffuse astrocytic and oligodendroglial tumors. Methods: The primary treatment of low-grade gliomas is surgery. Safe maximal resection is the widest possible resection without causing additional neurological damage. It increases survival and reduces existing neurological symptoms. Maximal safe resection may not be achieved because of tumor infiltration or proximity to sensitive motor/sensory function areas. Although radio diagnostic and surgical technique advancements have improved, residual tumors are detected in the majority of patients. Results: Adjuvant treatment of residual low-grade gliomas is controversial. The European Organisation for Research and Treatment of Cancer (EORTC) study showed that early radiotherapy after surgery extended progression-free survival for 2 years without an overall survival benefit. After this study, it has been adopted in clinical practice that high-risk patients receive early radiotherapy and low-risk groups receive radiotherapy after progression. Certain risk factors have been determined from Radiation Therapy Oncology Group (RTOG) and EORTC studies. The high-risk factors are age over 40 years, partial resection, tumor size over 5 cm, not having isocitrate dehydrogenase mutation, and tumor progression or recurrence. Adjuvant radiotherapy and concurrent chemotherapy are recommended achieving improved progression-free survival and overall survival in patients with high-risk factors. In the low-risk group, radiotherapy may be delayed until progression. Conclusions: Low-grade gliomas are slow progressing tumors. To detect progression in follow-up, it is recommended to compare follow-up magnetic resonance images with the initial reference magnetic resonance images, not with the previous control. Cite this article as: Dağdelen M, Demir E, Uzel ÖE. Radiotherapy in the treatment of low-grade gliomas. Cerrahpaşa Med J. February 12, 2022. 46(1):1-5.