Enis Ozyar

Enis Ozyar

*This is an algorithmically generated author record based on publicly available information.

Enis Ozyar has a total of 242 co-authors. Here are the top co-authors by number of shared publications:


Latest Publications

  • Open Access

    Global Disparities and Trends in Radiotherapy for Early-Stage Glottic Cancer

    by Issa Mohamad, Shatha Abu Taha, Ahmad Bushehri, Bassem Youssef, Enis Ozyar, Ibrahim Alotain, Ibrahim Abu-Gheida, Mohammed Aldehaim, Carlton Johnny, Layth Mula-Hussain, et al.

    We evaluated global radiotherapy practices in the management of early-stage (AJCC/UICC 8th edition stages I-II) glottic cancer (ESGC). A cross-sectional online survey was conducted in March 2025 across centers worldwide. Data was collected on clinical practices, including staging, CT simulation, target volumes delineation, organs-at-risk contouring, radiotherapy techniques, dose and fractionation schedules, treatment delivery techniques, and image guidance practices. A total of 181 responses were received, primarily from Asia (41.4%) and Europe (24.3%). Most respondents were from non-academic public centers (44.2%), with multidisciplinary team involvement reported by 84.5%. Head and neck CT scan was the most used staging modality (80.1%). Intensity-Modulated Radiation Therapy was the most common planning technique (82.9%). Hypofractionated radiotherapy schedules predominated for T1 (84%) and T2 (72.4%) disease. T1a was typically treated with whole-larynx target volume (72.4%). Use of ipsilateral involved vocal cord irradiation varied by geographical region (p = 0.015), being most common in North America (44.8%) and Europe (38.6%). Accelerated fractionation for T2 also differed significantly (p < 0.001), with the highest use reported in North America (41.4%). Daily Cone-Beam Computed Tomography was acquired by (58.2%). In total, 70% of respondents expressed interest in the results of a future phase III randomized trial comparing stereotactic body radiation therapy to conventional radiotherapy. Significant global variations in radiotherapy practices for ESGC were observed, likely reflecting disparities in access and differences in institutional protocols. The development and implementation of standardized, evidence-based global guidelines are essential to harmonize care, minimize toxicity, and improve outcomes for patients with ESGC.

  • Open Access

    Global Disparities and Trends in Radiotherapy for Early-Stage Glottic Cancer

    by Issa Mohamad, Shatha Abu Taha, Ahmad Bushehri, Bassem Youssef, Enis Ozyar, Ibrahim Alotain, Ibrahim Abu-Gheida, Mohammad Aldehaim, Carlton Johnny, Layth Mulla, et al.

    We evaluated global radiotherapy practices in the management of early-stage (AJCC/UICC 8th edition stages I-II) glottic cancer (ESGC). A cross-sectional online survey was conducted in March 2025 across centers worldwide. Data was collected on clinical practices, including staging, CT simulation, target volumes delineation, organs-at-risk contouring, radiotherapy techniques, dose and fractionation schedules, treatment delivery techniques, and image guidance practices. A total of 181 responses were received, primarily from Asia (41.4%) and Europe (24.3%). Most respondents were from non-academic public centers (44.2%), with multidisciplinary team involvement reported by 84.5%. Head and neck CT scan was the most used staging modality (80.1%). Intensity-Modulated Radiation Therapy was the most common planning technique (82.9%). Hypofractionated radiotherapy schedules predominated for T1 (84%) and T2 (72.4%) disease. T1a was typically treated with whole-larynx target volume (72.4%). Use of ipsilateral involved vocal cord irradiation varied by geographical region (p = 0.015), being most common in North America (44.8%) and Europe (38.6%). Accelerated fractionation for T2 also differed significantly (p < 0.001), with the highest use reported in North America (41.4%). Daily Cone-Beam Computed Tomography was acquired by (58.2%). 70% of respondents expressed interest in the results of a future phase III randomized trial comparing stereotactic body radiation therapy to conventional radiotherapy. Significant global variations in radiotherapy practices for ESGC were observed, likely reflecting disparities in access and differences in institutional protocols. The development and implementation of standardized, evidence-based global guidelines are essential to harmonize care, minimize toxicity, and improve outcomes for patients with ESGC.

  • Lorlatinib-Induced Blindness: A Rare Entity

    by Neris Dincer, Orcun Can, Gokhan Demir, Enis Ozyar


  • Open Access

    Clinical and radiological effects of Bevacizumab for the treatment of radionecrosis after stereotactic brain radiotherapy

    by Teuta Zoto Mustafayev, Menekse Turna, Yasemin Bolukbasi, Evrim Tezcanli, Yildiz Guney, Fazilet Oner Dincbas, Beste Melek Atasoy, Gamze Ugurluer, Hale Basak Caglar, Banu Atalar, et al.

    Purpose: The purpose of this multicenter retrospective study was to analyze the clinical and radiological effects of bevacizumab (BV) on radionecrosis (RN) that developed after stereotactic radiotherapy (SRT) for brain metastasis. Methods: Forty patients with SRT related symptomatic brain RN treated in 10 radiation oncology centers were analyzed. The clinical response to BV treatment was categorized as follows: complete (no additional treatment required), partial (requiring either steroids or repeat BV), and unresponsive (requiring surgery). The radiological features of brain RN were analyzed in 10 patients whose serial MRI scans were available after corticosteroid and BV treatments. Results: BV was used as a first line treatment in 11 (27.5%) and as a second line treatment in 29 (72.5%) of patients. The neurological symptoms regressed in 77.5% of patients after treatment with BV (45% complete response, 32.5% partial response). The median edema volume increased from 75.9 cc (range: 5.9-125.8 cc) at RN to 113.65 cc (range: 1.5-382.1 cc) after use of corticosteroids, representing a rate of 39.8% increase (p = 0.074). However, after BV treatment the median volume of edema decreased to 19.5 cc (range: 0-163.3 cc) which represents a difference of 62.2% (p = 0.041) from RN. Conclusion: The use of BV caused clinical response rate of 77.5% and a good radiological response in corticosteroid unresponsive patients. The role of BV should be further investigated in prospective studies.


  • Nuclear protein in testis (NUT) midline carcinoma of the larynx: A rare case report of a paediatric patient and literature review

    by G. Ugurluer, N. Dincer, A.E. Danyeli, L. Celik, A.L. Guner, F. Corapcioglu, C. Canpolat, Y.B. Kok, E. Ozyar


  • Open Access

    Factors influencing local control after MR-guided stereotactic body radiotherapy (MRgSBRT) for adrenal metastases

    by Gamze Ugurluer, Famke L. Schneiders, Stefanie Corradini, Luca Boldrini, Rupesh Kotecha, Patrick Kelly, Lorraine Portelance, Philip Camilleri, Merav A. Ben-David, Spencer Poiset, et al.


  • Open Access

    A multicenter retrospective analysis of patients with nasopharyngeal carcinoma treated in IMRT era from a nonendemic population: Turkish Society for Radiation Oncology Head and Neck Cancer Group Study (TROD 01‐001)

    by Halil Cumhur Yildirim, Gulnihan Eren Kupik, Teuta Zoto Mustafayev, Tanju Berber, Berrin Yavuz, Oguz Cetinayak, Ozlem Akagunduz, Beyhan Ceylaner Bıcakcı, Suheyla Aytac Arslan, Ela Delikgoz Soykut, et al.

    BackgroundWe aimed to evaluate patients with nasopharyngeal carcinoma (NPC) in a nonendemic population. MethodsIn a national, retrospective, multicenteric study, 563 patients treated with intensity modulated radiotherapy at 22 centers between 2015 and 2020 were analyzed. ResultsMedian age was 48 (9-83), age distribution was bimodal, 74.1% were male, and 78.7% were stage III-IVA. Keratinizing and undifferentiated carcinoma rates were 3.9% and 81.2%. Patients were treated with concomitant chemoradiotherapy (48.9%), or radiotherapy combined with induction chemotherapy (25%) or adjuvant chemotherapy (19.5%). After 34 (6-78) months follow-up, 8.2% locoregional and 8% distant relapse were observed. Three-year overall survival was 89.5% and was lower in patients with age >= 50, male sex, keratinizing histology, T4, N3 and advanced stage (III-IVA). ConclusionsPatients with NPC in Turkey have mixed clinical features of both east and west. Survival outcomes are comparable to other reported series; however, the rate of distant metastases seems to be lower.


  • Open Access

    Magnetic Resonance Imaging-Guided Radiation Therapy for Early-Stage Gastric Mucosa-Associated Lymphoid Tissue Lymphoma

    by Neris Dincer, Gamze Ugurluer, Gorkem Gungor, Teuta Zoto Mustafayev, Banu Atalar, Enis Ozyar

    Lymphoid neoplasia derived from mucosa-associated lymphoid tissue (MALT; also abbreviated as MALToma) is most commonly seen in the stomach. Radiotherapy (RT) is indicated in early-stage disease as a standard of care. With the advent of RT techniques, large field irradiation was replaced by involved site and involved field approaches. Magnetic resonance imaging-guided online adaptive RT (MRgRT) has the advantage of better soft tissue visualization, adaptive planning before each fraction, and online tumor tracking during treatment; hence, it could be a safe and effective choice for gastric MALToma patients. Herein, we investigated the interfractional changes in target and the impact of MRgRT on daily dosimetry in a gastric MALToma case. A patient diagnosed with MALToma who failed to respond to antibacterial treatment was referred to our clinic for RT. He was found to be suitable for MRgRT. We treated the patient with MRgRT in 20 fractions to a total dose of 30 Gy. Reoptimized adaptive plans were generated before each fraction since the coverages of the original plan were inadequate in each fraction. The patient showed good compliance and tolerated the treatment well. To our knowledge, this is the first documented case of a gastric MALToma treated with MRgRT. MRgRT is safe and feasible for this patient group with improved target coverage using small planning target volume margins. Without online adaptive planning, the target coverages would be inadequate and we would risk surrounding tissues to get higher doses.


  • Open Access

    Clinical adoption patterns of 0.35 Tesla MR-guided radiation therapy in Europe and Asia

    by Berend J. Slotman, Mary Ann Clark, Enis Özyar, Myungsoo Kim, Jun Itami, Agnès Tallet, Jürgen Debus, Raphael Pfeffer, PierCarlo Gentile, Yukihiro Hama, et al.

    Background: Magnetic resonance-guided radiotherapy (MRgRT) utilization is rapidly expanding, driven by advanced capabilities including better soft tissue imaging, continuous intrafraction target visualization, automatic triggered beam delivery, and the availability of on-table adaptive replanning. Our objective was to describe patterns of 0.35 Tesla (T)-MRgRT utilization in Europe and Asia among early adopters of this novel technology. Methods: Anonymized administrative data from all 0.35T-MRgRT treatment systems in Europe and Asia were extracted for patients who completed treatment from 2015 to 2020. Detailed treatment information was analyzed for all MR-linear accelerators (linac) and -cobalt systems. Results: From 2015 through the end of 2020, there were 5796 completed treatment courses delivered in 46,389 individual fractions. 23.5% of fractions were adapted. Ultra-hypofractionated (UHfx) dose schedules (1–5 fractions) were delivered for 63.5% of courses, with 57.8% of UHfx fractions adapted on-table. The most commonly treated tumor types were prostate (23.5%), liver (14.5%), lung (12.3%), pancreas (11.2%), and breast (8.0%), with increasing compound annual growth rates (CAGRs) in numbers of courses from 2015 through 2020 (pancreas: 157.1%; prostate: 120.9%; lung: 136.0%; liver: 134.2%). Conclusions: This is the first comprehensive study reporting patterns of utilization among early adopters of a 0.35T-MRgRT system in Europe and Asia. Intrafraction MR image-guidance, advanced motion management, and increasing adoption of on-table adaptive RT have accelerated a transition to UHfx regimens. MRgRT has been predominantly used to treat tumors in the upper abdomen, pelvis and lungs, and increasingly with adaptive replanning, which is a radical departure from legacy radiotherapy practices.