Researcher:
Selek, Uğur

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Uğur

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Selek

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Selek, Uğur

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2012 - 2019492020 - 202339

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    Assessment of the impact of osteoradionecrosis on quality-of-life measures in patients with head and neck cancer
    (Exon Publishing, 2023) Somay E; Yilmaz B; Topkan E; Kucuk A; Pehlivan B; Selek, Uğur; School of Medicine
    Osteoradionecrosis of the jaws is a serious complication of radiotherapy that frequently results in facial deformity, pain, fracture, devitalized bone, fistulas, dysesthesia or anesthesia, trismus, difficulty chewing, swallowing, and localized or systemic infections. Osteoradionecrosis is defined as “a potentially severe, delayed radiation-induced injury characterized by bone necrosis, failure to heal, and exposed bone for at least three months in the absence of primary tumor progression or recurrence, or metastatic disease”. The incidence rate of osteonecrosis among patients with head and neck cancers treated with radiotherapy or concurrent chemo-radiotherapy is 2–22%. Although the incidence of osteoradionecrosis of the jaws has decreased as a result of recent improvements in radiotherapy procedures, it is still a very challenging task to predict, prevent, and treat osteoradionecrosis of the jaws and its consequences on patients’ quality of life. Despite the negative impacts of osteoradionecrosis of the jaws on sufferers’ physical appearance and functioning, and social relationships, there is a paucity of research on the quality-of-life that is specific to this condition. This chapter provides a summary of the available data on the physical, social, and emotional effects of osteoradionecrosis of the jaws as determined by general or head and neck cancer-specific quality of life surveys, which may be used to evaluate and treat such patients in radiation oncology and dentistry practices.
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    Prophylactic cranial irradiation in small and non-small-cell lung carcinoma
    (Springer, 2016) Topkan, Erkan; N/A; Selek, Uğur; Faculty Member; School of Medicine; 27211
    At initial presentation, approximately 10–14 % of small-cell lung carcinoma (SCLC) patients manifest with radiologically evident brain metastases (BM) which arises up to 69 % at 2 years. Similarly, brain failures are reported in 21–54 % of all non-small-cell lung carcinoma (NSCLC) patients, and of these, the brain is the first site of relapse in 15–30 % cases. Although significant improvements have been achieved in local and distant control of both SCLC and NSCLC as a result of implementation of aggressive treatment modalities, unfortunately such aggressive treatments proved no noteworthy viability in lessening of overall brain or brain as the first site of relapse rates. Regarding its counteractive actions on BM emergence, the potential beneficial effects of prophylactic cranial irradiation (PCI) in patients with limited-stage SCLC (LS-SCLC), extensive-stage SCLC (ES-SCLC), and locally advanced NSCLC (LA-NSCLC) have been addressed with several randomized trials and meta-analysis. Based on the results of these investigations, PCI of 25 Gy (2.5 Gy in ten fractions) should be recommended for all medically fit LS- and ES-SCLC patients with any objective response to primary therapy in order to reduce BM incidence rates and to prolong OS times. Although the PCI studies in LA-NSCLC patients suggest significant reductions in BM incidence rates with PCI, yet in the absence of an established survival benefit, it is currently quite difficult to recommend its routine use in LA-NSCLC patients. However, future studies involving high-risk patients may prove worthy in determination of the exact impact if they are needed in order to reliably comment on the issue of PCI in LA-NSCLC patients.
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    Investigation of ionizing radiation response in new resistance models of glioblastoma.
    (Amer Assoc Cancer Research, 2021) N/A; N/A; Değirmenci, Nareg Pınarbaşı; Önder, Tuğba Bağcı; Sur, İlknur Erdem; Selek, Uğur; PhD Student; Faculty Member; Faculty Member; Faculty Member; Koç University Research Center for Translational Medicine (KUTTAM) / Koç Üniversitesi Translasyonel Tıp Araştırma Merkezi (KUTTAM); Graduate School of Health Sciences; School of Medicine; School of Medicine; School of Medicine; N/A; 184359; N/A; 27211
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    Pre-chemoradiotherapy low hemoglobin levels indicate increased osteoradionecrosis risk in locally advanced nasopharyngeal cancer patients
    (Springer Science and Business Media Deutschland GmbH, 2023) Yılmaz, Büşra; Somay Efsun; Topkan Erkan; Pehlivan Berrin; N/A; Selek, Uğur; Faculty Member; School of Medicine; 27211
    Purpose: We aimed to determine whether pretreatment hemoglobin (Hb) levels can predict the risk of osteoradionecrosis (ORN) in patients receiving concurrent chemoradiotherapy (CCRT) for locally advanced nasopharyngeal carcinoma (LA-NPC). Methods: ORN cases were identified from the records of LA-NPCs who had oral exams before and after CCRT. All Hb measurements were obtained on the first day of treatment. Receiving operating characteristic curve analysis was used to determine the relationship between Hb levels and ORN rates. The relationship between pretreatment Hb levels and ORN rates served as the primary endpoint, and secondary endpoints included the discovery of additional potential ORN risk factors. Results: Among the 263 eligible LA-NPCs, we identified 8.7% ORN cases. The ideal cutoff Hb before CCRT was 10.6 g/dL. It was revealed that HPR ≤ 10.6 group had a significantly higher ORN rate (32.5% vs. 1.5% for Hb > 10.6; P < 0.001). The mandibular V59.8 ≥ 36% Gy, pre-CCRT ≥ 4 tooth extractions, the presence of post-CCRT tooth extractions, and the time of post-CCRT tooth extractions > 8 months were the other factors associated with significantly increased ORN rates (P < 0.05 for each). Conclusion: Low pre-CCRT Hb levels appeared to be independently linked to significantly higher ORN rates. Pretreatment Hb levels may be used to establish preventive measures and predict ORN.
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    Pretreatment pan-immune-inflammation value efficiently predicts survival outcomes in glioblastoma multiforme patients receiving radiotherapy and temozolomide
    (Hindawi Ltd, 2022) Topkan, Erkan; Küçük, Ahmet; N/A; Selek, Uğur; Faculty Member; School of Medicine; 27211
    Objectives: The purpose of this study was to determine the predictive significance of pretreatment pan-immune-inflammation value (PIV) in patients with newly diagnosed glioblastoma multiforme (GBM) who received postsurgical radiation (RT) and concurrent plus adjuvant temozolomide (TMZ). Methods: The outcomes of 204 newly diagnosed GBM patients were analyzed retrospectively. Each eligible patient's PIV was calculated using the findings of peripheral blood platelet (P), monocyte (M), neutrophil (N), and lymphocyte (L) counts obtained on the first day of therapy: PIV=PxMxN and DIVIDE;L. We used receiver operating characteristic (ROC) curve analysis to discover the ideal cutoff values for PIV concerning progression-free (PFS) and overall survival (OS) outcomes. The primary and secondary end-points were the OS and PFS divergences across the PIV groups. Results: In ROC curve analysis, the optimal PIV cutoff was 385, which substantially interacted with PFS and OS results and categorized patients into low PIV (L-PIV; N=75) and high PIV (H-PIV; N=129) groups. Comparative survival analyses showed that the patients in the H-PIV group had significantly shorter median PFS (6.0 vs. 16.6 months; P < 0.001) and OS (11.1 vs. 22.9 months; P < 0.001) durations than those in the L-PIV group. The results of multivariate Cox regression analysis indicated an independent and significant connection between an H-PIV measure and shorter PFS and OS outcomes. Conclusions: The novel PIV was able to independently stratify newly diagnosed GBM patients into two groups with fundamentally different PFS and OS outcomes following RT and concurrent plus adjuvant TMZ.
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    Molecular evidence against the preventive actions of GnRH agonists in chemotherapy induced damage in human ovary and granulosa cells
    (2015) Güzel, Y.; Urman, B; N/A; Bildik, Gamze; Akın, Nazlı; Taşkıran, Çağatay; Selek, Uğur; Öktem, Özgür; Teaching Faculty; Master Student; Faculty Member; Faculty Member; Faculty Member; School of Medicine; Graduate School of Health Sciences; School of Medicine; School of Medicine; School of Medicine; Koç University Hospital; N/A; N/A; 134190; 27211; 102627
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    Case presentation: the effect of volumetric image guidance and adaptive radiotherapy on cardiac dose in a patient with esophageal cancer
    (Kare Publ, 2018) Sağlam, Yücel; Alpan, Vildan; N/A; N/A; N/A; N/A; N/A; Sezen, Duygu; Bölükbaşı, Yasemin; Durankuş, Nilüfer Kılıç; Atasoy, Ali İhsan; Selek, Uğur; Faculty Member; Faculty Member; Teaching Faculty; Other; Faculty Member; School of Medicine; School of Medicine; School of Medicine; School of Medicine; School of Medicine; 170535; 216814; 148139; N/A; N/A; N/A; 27211
    We present the case of a patient with esophageal cancer whose tumor size regression prompted re-planning to decrease the cardiac dose. A 68-year-old male presented at our outpatient clinic with dysphagia. He was diagnosed with clinical T3N1 M0 adenocarcinoma located at the distal esophagus-esophagogastric junction. He was decided to have surgery after receiving neoadjuvant chemoradiotherapy. Following 4-D CT simulation, IG-IMRT with SIB technique was planned as 50 Gy in 25 fractions to iGTV and as 45 Gy to the area identified as the CIV. Daily kV and weekly CBCI were planned at the beginning of the treatment. Concurrent CT with weekly paclitaxel-carboplatin was administered. At the simulation and start of the treatment, the heart was pushed anteriorly due to the mass effect and dilatation in the mid-lower esophagus. The mass and dilatation regressed at the weekly CBCT of the patient. The third-week CBCT evaluation revealed the movement of the heart posteriorly into the PTV. Re-simulation was performed to continue with the adaptive planning for the last 10 treatment fractions. The cumulative dose received by the heart was reduced from 96% to 93% for V5Gy, from 79% to 60.8% for V10Gy, from 60% to 43.2% for V15Gy, from 35% to 21% for V20Gy, and from 29.6 to 28 Gy for the mean cardiac dose with the volumetric image-guided adaptive planning. If tumor regression is predicted during radiotherapy to possibly change doses of organs at risk, volumetric image guidance should be encouraged once per week, at least, to consider adaptive treatment when required to ensure the critical organ doses within safe limits.
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    Principles and practice of urooncology: radiotherapy, surgery and systemic therapy
    (Springer, 2017) Özyiğit, Gökhan; N/A; Selek, Uğur; Faculty Member; School of Medicine; 27211
    This evidence-based, state of the art guide to the management of urological malignancies, including bladder cancer, prostate cancer, and testicular cancer, is designed to serve as an easy-to-consult reference that will assist in daily decision making and the delivery of optimal care for individual patients within a multidisciplinary setting. Readers will find up-to-date information on patient selection and the full range of treatment modalities, including modern radiotherapy techniques, systemic chemotherapy, surgical procedures (including robotic surgery and other minimally invasive approaches), hormonal therapies, immunotherapy, and focal therapies. With regard to radiotherapy, the coverage encompasses everything from delineation of tumor volumes and organs at risk based on CT simulation through to delivery of stereotactic body radiotherapy, intensity-modulated radiation therapy, tomotherapy, volumetric modulated arc therapy, and proton therapy. The authors are leading authorities with international reputations who have been selected for their expertise in the topic that they address. The book will be of value for all practicing urooncologists as well as other oncology fellows and residents interested in urooncology.
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    Safety of combined immunotherapy and thoracic radiation therapy: analysis of 3 single-institutional phase I/II trials
    (Elsevier Science Inc, 2018) Verma, Vivek; Cushman, Taylor R.; Tang, Chad; Welsh, James W.; Selek, Uğur; Faculty Member; School of Medicine; 27211
    Purpose: The safety of combined immunotherapy and thoracic radiation therapy (iRT) has been understudied. We evaluated toxicities in patients receiving iRT from 3 single-institutional phase 1/2 trials. Methods and Materials: Clinical/treatment characteristics and toxicities (per the Common Toxicity Criteria for Adverse Events, version 4.0) were extracted. For purposes of this analysis, groupings were made into (1) patients receiving immunotherapy plus stereotactic body radiation therapy (50 Gy/4 fractions or 60 Gy/10 fractions), (2) immunotherapy plus 45 Gy/15 fractions, and (3) twice-daily chemoimmunoradiotherapy (45 Gy in twice-daily fractions). Results: None of the 60 patients undergoing immunotherapy plus stereotactic body radiation therapy (50 Gy, n = 49; 60 Gy, n = 11) experienced grade >= 4 events. There were 34 instances of any grade 3 event (in 15 total patients), with 9 pulmonary specific grade 3 events (in 4 patients). In the patients receiving 45 Gy/15 fractions (small cell lung cancers, n = 26; non-small cell lung cancers, n = 27), there were 2 grade 4 events (in the same patient), along with 17 grade 3 toxicities experienced by 10 total patients (2 pulmonary specific). Lastly, in the twice-daily cohort (n = 22), there were 5 grade 4 events (3 of which occurred in 1 patient) and 16 grade 3 toxicities occurring in 8 total patients (half of which were hematologic). Conclusions: Administration of combined iRT is safe in the short term. Toxicities did not appreciably associate with demographics or dosimetry.
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    Low regrowth after cCR in non-operative TNT management of locally advanced rectal cancer patients
    (Elsevier Ireland Ltd, 2022) N/A; N/A; N/A; N/A; N/A; N/A; N/A; Selek, Uğur; Selçukbiricik, Fatih; Özoran, Emre; Balık, Emre; Bölükbaşı, Yasemin; Mandel, Nil Molinas; Buğra, Dursun; Faculty Member; Faculty Member; Teaching Faculty; Faculty Member; Faculty Member; Faculty Member; Faculty Member; School of Medicine; School of Medicine; School of Medicine; School of Medicine; School of Medicine; School of Medicine; School of Medicine; 27211; 202015; 307296; 18758; 216814; 194197; 1758
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