Browsing by Author "Sahin, Bilgehan"

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Carotid blowout syndrome after intensity-modulated radiation therapy: A case report
(MARMARA UNIV, FAC MEDICINE, 2017-01-01) Sahin, Bilgehan; Atalar, Banu; Yakupoglu, Abdullah; Ozyar, Enis
Carotid blowout syndrome (CBS) is a rarely seen complication of head-neck surgery and radiation therapy. It may present by massive ear bleeding or epistaxis with high morbidity and mortality rates. Success rate of endovascular therapy or emergency surgery is unfortunately low because of massive bleeding and weakened vessel architecture. Here, we present a 45-year-old male with nasopharyngeal carcinoma and treated with intensity-modulated radiation therapy (IMRT) and concurrent chemotherapy. The patient was diagnosed with stage III (T3N2M0) carcinoma of the nasopharynx. Eight months after radiotherapy, he was admitted to hospital with the complaint of epistaxis. Right internal carotid angiography revealed a 4 mm pseudoaneurysm at the superior-anterior wall of the petrous and his bleeding was controlled by stenting in the same session. In this report we aimed to draw attention to this rare clinical situation that might enhance the chance of early diagnosis enabling less morbid treatment opportunities.
Evaluation of response to stereotactic radiosurgery in patients with radioresistant brain metastases
(KOREAN SOC THERAPEUTIC RADIOLOGY \& ONCOLOGY, 2019-01-01) Sayan, Mutlay; Mustafayev, Teuta Zoto; Sahin, Bilgehan; Kefelioglu, Erva Seyma Sare; Wang, Shang-Jui; Kurup, Varsha; Balmuk, Aykut; Gungor, Gorkem; Ohri, Nisha; Weiner, Joseph; Ozyar, Enis; Atalar, Banu
Purpose: Renal cell carcinoma (RCC) and melanoma have been considered `radioresistant' due to the fact that they do not respond to conventionally fractionated radiation therapy. Stereotactic radiosurgery (SRS) provides high-dose radiation to a defined target volume and a limited number of studies have suggested the potential effectiveness of SRS in radioresistant histologies. We sought to determine the effectiveness of SRS for the treatment of patients with radioresistant brain metastases. Materials and Methods: We performed a retrospective review of our institutional database to identify patients with RCC or melanoma brain metastases treated with SRS. Treatment response were determined in accordance with the Response Evaluation Criteria in Solid Tumors. Results: We identified 53 radioresistant brain metastases (28\% RCC and 72\% melanoma) treated in 18 patients. The mean target volume and coverage was 6.2 +/- 9.5 mL and 95.5\% +/- 2.9\%, respectively. The mean prescription dose was 20 +/- 4.9 Gy. Forty lesions (75\%) demonstrated a complete/partial response and 13 lesions (24\%) with progressive/stable disease. Smaller target volume (p < 0.001), larger SRS dose (p < 0.001), and coverage (p = 0.008) were found to be positive predictors of complete response to SRS. Conclusion: SRS is an effective management option with up to 75\% response rate for radioresistant brain metastases. Tumor volume and radiation dose are predictors of response and can be used to guide the decision-making for patients with radioresistant brain metastases.
First 500 Fractions Delivered with a Magnetic Resonance-guided Radiotherapy System: Initial Experience
(CUREUS INC, 2019-01-01) Sahin, Bilgehan; Mustafayev, Teuta Zoto; Gungor, Gorkem; Aydin, Gokhan; Yapici, Bulent; Atalar, Banu; Ozyar, Enis
Objectives Improved soft-tissue visualization, afforded by magnetic resonance imaging integrated into a radiation therapy linear accelerator-based radiation delivery system (MR-linac) promises improved image-guidance. The availability of MR-imaging can facilitate on-table adaptive radiation planning and enable real-time intra-fraction imaging with beam gating without additional exposure to radiation. However, the novel use of magnetic resonance-guided radiation therapy (MRgRT) in the field of radiation oncology also potentially poses challenges for routine clinical implementation. Herein the early experience of a single institution, implementing the first MRgRT system in the country is reported. We aim to describe the workflow and to characterize the clinical utility and feasibility of routine use of an MR-linac system. Methods The ViewRay MRIdian MR-linac system consists of a split-magnet 0.35 T MR-imaging scanner with a double focused multi-leaf collimator (MLC) equipped 6MV linear accelerator. Unique to the system are the control console integrated on-table adaptive radiation therapy (oART) planning capabilities as well as automated beam gating based on real-time intra-fraction MR imaging. From the first day of clinical implementation, oART was performed according to physicians' discretion when medically indicated. All fractions were delivered under real-time imaging with soft tissue-based automated beam gating with individualized gating boundary settings. Patients actively assisted in breath-hold beam gating with the help of custom designed prismatic glasses allowing sight of a computer monitor mounted on the back wall just behind the MRI system bore. Patient demographics and treatment experience, indications for MRgRT including diagnosis and disease site, radiation dose prescribed and fractionation scheme, utilization of oART, respiratory gating settings, as well as duration of each treatment phase were analyzed. Results Between September 2018 and May 2019, 72 patients with 84 tumor sites were treated with MRgRT in 500 total fractions. Median patient age was 66 years (range: 28-83 years). Among 84 tumor sites, the most frequently treated regions were upper abdominal and pelvic (n = 36, 43\% and n = 29, 34\%, respectively). The most common diagnosis was prostate cancer, with 14 patients treated. In 69 patients (93.2\%) oART was used at least once during a treatment course. Twenty-nine targets (43.1\%) with significant breathing-related motion were treated in breath-hold with patient visual feedback. Median prescribed dose was 36.25 Gy (range: 24-70 Gy) in median five fractions (range: 3-28 fractions). A gating boundary of 3 mm around a gating region of interest (gROI) was most commonly used (range: 3-5 mm) with 95\% of the gROI (range: 93-97\%) required to be within the gating boundary for the beam to automatically engage. Mean total treatment time was 47 min (range: 21-125 min) and mean beam-on time was 16.7 min (range: 6-62 min). Conclusions MRgRT afforded by an MR-linac system has been successfully implemented into routine clinical use at our institution as the first system of its kind in Turkey. While the overall number of patients treated and fractions delivered is still limited, we have demonstrated the feasibility of both on-table adaptive radiation therapy as well as automated real-time beam gating on a daily basis in acceptable time schedules.
Long-term toxicity and survival outcomes after stereotactic ablative radiotherapy for patients with centrally located thoracic tumors
(WALTER DE GRUYTER GMBH, 2020-01-01) Atalar, Banu; Mustafayev, Teuta Zoto; Sio, Terence T.; Sahin, Bilgehan; Gungor, Gorkem; Aydin, Gokhan; Yapici, Bulent; Ozyar, Enis
Background. Stereotactic ablative radiotherapy (SABR) is effective for thoracic cancer and metastases
Non-small Cell Lung Cancer with Multiple Brain Metastases Treated with Radiosurgery and Erlotinib: A Case Report
(CUREUS INC, 2017-01-01) Sahin, Bilgehan; Mustafayev, Teuta; Aydin, Gokhan; Gungor, Gorkem; Yapici, Bulend; Atalar, Banu; Ozyar, Enis
Brain metastases are commonly seen complications in non-small cell lung cancer (NSCLC) patients. The incidence of brain metastases is increasing as a result of more effective systemic targeted therapies with prolonged survival. The prognosis is usually poor, and up to six months of median survivals were reported with different therapeutic options. Here, we present an NSCLC case with multiple brain metastases treated with radiosurgery and systemic erlotinib therapy with prolonged survival. The use of tyrosine kinase inhibitors (TKI) in conjunction with either stereotactic radiosurgery or whole brain radiotherapy is not well established in terms of efficiency and toxicity. This reported case had an excellent response with a tolerable toxicity profile from the combination of either therapies.
Re-Irradiation of Non-Small Cell Lung Cell Cancer Recurrences with Stereotactic Body Radiotherapy
(2016-01-01) Atalar, Banu; Sahin, Bilgehan; Gungor, Gorkem; Aydin, Gokhan; Yapici, Bulent; Ozyar, Enis