Tıp Fakültesi / Faculty of Medicine

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Author: search.filters.author.Guler, Ozan C.

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    Prognostic Value of 18F-Fluorodeoxyglucose Uptake in Pelvic Lymph Nodes in Patients with Cervical Cancer Treated with Definitive Chemoradiotherapy
    (2015) Onal, Cem; Guler, Ozan C.; Reyhan, Mehmet; Yapar, Ali Fuat; 0000-0001-6908-3412; 0000-0003-1715-4180; 0000-0002-2742-9021; 0000-0001-8550-3368; 25641567; AAC-5654-2020; AAI-8973-2021; D-5195-2014; AAJ-5242-2021; HOC-5611-2023
    Purpose. To evaluate the prognostic significance of the maximum standardized uptake (SUVmax) value for pelvic lymph nodes in patients with cervical cancer and its impact on treatment response, disease control, and survival. Methods. Ninety-three patients with pelvic or para-aortic metastasis detected by PET/CT and treated with definitive chemoradiotherapy were evaluated. The impact of pelvic lymph node SUVmax on prognostic factors and treatment outcomes was assessed. Results. The size and SUVmax of pelvic lymph nodes were significantly correlated (r = 0.859; p < 0.001). Patients with pelvic and para-aortic lymph node metastases had significantly higher SUVmax values for both primary tumor (23.4 +/- 9.2 vs. 18.5 +/- 73; p = 0.01) and pelvic lymph nodes (11.4 +/- 4.6 vs. 7.4 +/- 3.8; p = 0.001). Patients with pelvic lymph node SUVmax >= 7.5 had significantly higher primary tumor SUVmax, larger pelvic lymph nodes, higher rates of para-aortic lymph node metastasis, and lower post-therapy complete response rates. Overall survival (OS) and disease-free survival (DFS) rates were significantly higher in patients with SUVmax < 7.5 compared to patients with SUVmax >= 7.5. In a multivariate analysis, pelvic lymph node SUVmax and post-therapy metabolic response were significant prognostic factors for both OS and DFS for all patients, but no significant prognostic factors were found in pelvic lymph node metastasis only. Conclusions. Patients with highly FDG-avid pelvic lymph nodes have a higher risk of disease recurrence with worse survival. Identification of these patients may assist in the evaluation of the clinical benefits of additional treatments. (C) 2015 Elsevier Inc. All rights reserved.
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    Treatment Outcomes of Patients with Cervical Cancer with Complete Metabolic Responses After Definitive Chemoradiotherapy
    (2014) Onal, Cem; Reyhan, Mehmet; Guler, Ozan C.; Yapar, Ali Fuat; https://orcid.org/0000-0002-2742-9021; https://orcid.org/0000-0001-8550-3368; https://orcid.org/0000-0001-6908-3412; https://orcid.org/0000-0003-1715-4180; 24562649; HOC-5611-2023; AAJ-5242-2021; AAC-5654-2020; AAI-8973-2021
    Purpose We sought to evaluate failure patterns and prognostic factors predictive of recurrences and survival in cervical cancer patients who are treated with definitive chemoradiotherapy (ChRT), who have a subsequent complete metabolic response (CMR) with (18) F-fluorodeoxyglucose positron-emission tomography (FDG-PET) after treatment. Methods The records of 152 cervical cancer patients who were treated with definitive chemoradiotherapy were evaluated. All patients underwent pre-treatment positron emission tomography (PET-CT), and post-treatment PET-CT was performed within a median of 3.9 months (range, 3.0-9.8 months) after the completion of ChRT. The prognoses of partial response/progressive disease (PR/PD) cases (30 patients, 18 %) and CMR cases (122 patients, %82) were evaluated. Univariate and multivariate analysis effecting the treatment outcome was performed in CMR cases. Results The median follow-ups for all patients and surviving patients were 28.7 (range, 3.3-78.7 months) and 33.2 months (range, 6.23-78.7 months), respectively. Four-year overall survival (OS) rate was significantly better in patients with CMR compared to patients with PR/PD (66.9 % vs. 12.4 %, p < 0.001, respectively). Patients with PR/PD had higher maximum standardized uptake value (SUVmax) of primary cervical tumor (26.4 +/- 10.1 vs. 15.9 +/- 6.3; p < 0.001) and larger tumor (6.4 cm +/- 2.3 cm vs. 5.0 cm +/- 1.4 cm; p < 0.001) compared to patients with CMR. Of the 122 patients with post-treatment CMRs, 25 (21 %) developed local, locoregional, or distant failure. In univariate analysis, tumor size a parts per thousand yen 5 cm, 'International Federation of Obstetricians and Gynecologists' (FIGO) stage a parts per thousand yenaEuro parts per thousand IIB, and pelvic and/or para-aortic lymph node metastasis were predictive of both overall survival (OS) and disease-free survival (DFS), while histology was predictive of only OS. In multivariate analysis, tumor size, stage and lymph node metastasis were predictive of OS and DFS. Conclusion Although CMR is associated with better outcomes, relapses remain problematic, especially in patients with bulky tumors (a parts per thousand yen 5 cm), extensive stage (a parts per thousand yen IIB) or pelvic and/or para-aortic lymph node metastasis. These findings could support the need for more aggressive treatment or adjuvant chemotherapy regimens.
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    Survival Analysis of 51 Leptomeningeal Metastatic Non Small Cell Lung Cancer Patients Treated with Whole Brain Radiotherapy
    (2015) Topkan, Erkan; Yildirim, Berna Akkus; Guler, Ozan C.; Ozdemir, Yurday; 0000-0001-6908-3412; 0000-0001-8120-7123; 0000-0001-6661-4185; 0000-0002-2218-2074; AAC-5654-2020; AAG-2213-2021; V-5717-2017; AAG-5629-2021
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    Weight Loss before Radical Chemoradiotherapy Is Associated with Poorer Survival Outcomes in Overweight Locally Advanced NSCLC Patients
    (2015) Topkan, Erkan; Yildirim, Berna Akkus; Ozdemir, Yurday; Guler, Ozan C.; Ozyilkan, Ozgur; 0000-0001-6661-4185; 0000-0002-2218-2074; 0000-0001-8825-4918; 0000-0001-8120-7123; 0000-0001-6908-3412; V-5717-2017; AAG-5629-2021; AAD-2817-2021; AAG-2213-2021; AAC-5654-2020
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    Effective Resolution of Lung Cancer Related Tracheal and/or Bronchial Obstruction with External Beam Radiotherapy
    (2015) Topkan, Erkan; Yildirim, Berna Akkus; Ozdemir, Yurday; Guler, Ozan C.; Kose, Fatih; 0000-0001-6908-3412; 0000-0001-8120-7123; 0000-0002-2218-2074; 0000-0001-6661-4185; AAC-5654-2020; AAG-2213-2021; AAG-5629-2021; V-5717-2017
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    Factors Associated with Brain Metastasis Development in Radically Treated Stage IIIB Non-Small Cell Lung Cancer Patients
    (2015) Topkan, Erkan; Yildirim, Berna Akkus; Guler, Ozan C.; Ozdemir, Yurday; 0000-0001-6908-3412; 0000-0001-6661-4185; 0000-0001-8120-7123; 0000-0002-2218-2074; AAC-5654-2020; V-5717-2017; AAG-2213-2021; AAG-5629-2021
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    Prognostic Value of Metabolic Tumor Volume and Total Lesion Glycolysis in Esophageal Carcinoma Patients Treated with Definitive Chemoradiotherapy
    (2018) Yildirim, Berna A.; Torun, Nese; Guler, Ozan C.; Onal, Cem; 0000-0001-6908-3412; 0000-0001-6661-4185; 0000-0002-2742-9021; 0000-0002-5597-676X; 29668513; AAC-5654-2020; V-5717-2017; D-5195-2014; AAE-2718-2021
    PurposeThe aim of this study was to evaluate the prognostic importance metabolic tumor volume (MTV), total lesion glycolysis (TLG), and standardized uptake value (SUV) in patients with esophageal cancer treated with definitive chemoradiotherapy.Patients and methodsSeventy-two esophageal cancer patients treated with definitive chemoradiotherapy [57 (79%) patients] or definitive radiotherapy [15 (21%) patients] were retrospectively analyzed. The regions equal to or greater than SUV of 2.5 were selected to delineate MTV and TLG was calculated by multiplying the mean SUV by the MTV of the primary lesions. The overall survival (OS) and disease-free survival (DFS) were evaluated for all patients and also patients with squamous cell carcinoma.ResultsThe median survival time was 13.4 months (range: 1.8-119.3 months) for all patients. Maximum SUV, mean SUV, MTV, and TLG values were significantly higher in patients with extensive T-stage (T3-T4) compared with patients with T1-T2 disease. Patients with regional lymph node metastasis had significantly higher MTV and TLG values compared with patients with no lymph node metastasis. On multivariate analysis, MTV, TLG, presence of lymph node metastasis, and lack of concurrent chemotherapy were negative significant prognostic factors for OS and DFS for the entire cohort and for patients with squamous cell carcinoma esophageal cancer.ConclusionMetabolic volumes (MTV and TLG), regional lymph node metastasis, and concurrent chemotherapy are major prognostic factors for DFS and OS in patients with esophageal carcinoma. In addition, MTV and TLG are important in predicting nodal metastasis, and together with metabolic volumes, SUV are associated significantly with local tumor invasion.
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    Prognostic Use of Pretreatment Hematologic Parameters in Patients Receiving Definitive Chemoradiotherapy for Cervical Cancer
    (2016) Onal, Cem; Guler, Ozan C.; Yildirim, Berna A.; 0000-0002-2742-9021; 0000-0001-6661-4185; 0000-0001-6908-3412; 27206286; D-5195-2014; V-5717-2017; AAC-5654-2020
    Objectives: The aim of this work was to evaluate the prognostic role of pretreatment neutrophil-to-lymphocyte ratio (NLR) and platelet-to-lymphocyte ratio (PLR) in recipients of definitive chemoradiotherapy (ChRT) for cervical cancer. Methods: In 235 patients given definitive ChRT for histologically confirmed cervical cancer, clinical data and pretreatment complete blood cell counts were analyzed. Prognostic and therapeutic ramifications of NLR and PLR were assessed. Results: Median pretreatment NLR and PLR were 3.03 (range, 1.04-13.03) and 133.02 (range, 36.3-518.16), respectively. Both NLR and PLR correlated significantly with tumor size, lymph node metastasis, and treatment response. In addition to NLR and PLR, tumor stage, size, and nodal metastasis were identified by univariate analysis as significant predictors of overall survival (OS) and progression-free survival (PFS). By multivariate analysis, independent predictors of OS and PFS were NLR (OS: hazard ratio [HR], 3.322; 95% confidence interval [CI], 1.905-5.790; PFS: HR, 3.579; 95% CI, 2.106-6.082; both P < 0.001) and lymph node metastasis (OS: HR, 2.620; 95% CI, 1.706-4.023; PFS: HR, 2.989; 95% CI, 1.918-4.378; both P < 0.001), although patients' age (HR, 1.019; 95% CI, 1.003-1.035; P = 0.02) was also significantly predictive of OS. Conclusions: Pretreatment NLR and PLR were associated with larger tumors, lymph node metastasis, and poorer therapeutic responses to definitive ChRT. By multivariate analysis, pretreatment NLR and lymph node metastasis were found independently predictive of OS and PFS, whereas patients' age was significantly predictive of OS only. In patients with advanced cervical cancer, NLR is a potential biomarker, serving to guide systemic therapy and predict treatment outcomes.
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    Prognostic Value of Metabolic Response Measured by F-18-FDG-PET in Oesophageal Cancer Patients Treated with Definitive Chemoradiotherapy
    (2016) Onal, Cem; Torun, Nese; Guler, Ozan C.; Yildirim, Berna A.; 0000-0002-2742-9021; 0000-0001-6661-4185; 0000-0002-5597-676X; 0000-0001-6908-3412; 27612030; D-5195-2014; V-5717-2017; AAE-2718-2021; AAC-5654-2020
    BackgroundThis study aimed to assess the efficacy of fluorine-18 fluorodeoxyglucose (F-18-FDG)-PET for predicting overall survival (OS) and disease-free survival (DFS) in oesophageal cancer patients after definitive chemoradiotherapy (CRT) and prognostic importance of metabolic response detected by post-treatment PET at least 3 months after completing CRT.Materials and methodsData from 58 oesophageal cancer patients receiving definitive CRT were retrospectively analysed. Post-treatment F-18-FDG-PET was delivered at a median of 3.2 (range, 3.0-6.4) months after CRT. The impact of metabolic response determined by post-treatment F-18-FDG-PET, maximum post-treatment standardized uptake value (SUVmax) and percent SUV change (pretreatment to post-treatment) on survival was analysed.ResultsThe median follow-up was 19.7 (range, 4.2-91.9) months for all patients and 28.2 (range, 13.7-91.9) months for survivors. The mean pretreatment and post-treatment SUVmax and the median percent SUV decrease were 18.66.4, 6.2 +/- 4.6 and -73% (+13 to -100%). Pretreatment SUVmax was higher in patients with locoregional or distant failure than in those without (P<0.001). Pretreatment SUVmax was lower in patients with a complete response (CR) than in those without a CR (P=0.006). Two-year OS and DFS were higher in patients with CR compared with those without CR (P<0.001). CR rates detected by post-treatment F-18-FDG-PET were lower in patients with lymph node metastases or longer tumours than in those with shorter tumours or no metastases. During multivariate analysis, post-treatment SUVmax was a significant predictor for OS, and post-treatment SUVmax, percent SUV decrease and tumour length were significant prognostic factors for DFS.ConclusionMetabolic response assessed by post-treatment F-18-FDG-PET at least 3 months after CRT showed that post-treatment SUVmax and percent SUV change were important survival predictors.
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    Predicting Tumor Recurrence in Patients with Cervical Carcinoma Treated with Definitive Chemoradiotherapy: Value Of Quantitative Histogram Analysis On Diffusion-Weighted MR Images
    (2017) Erbay, Gurcan; Onal, Cem; Karadeli, Elif; Guler, Ozan C.; Arica, Sami; Koc, Zafer; https://orcid.org/0000-0002-1706-8680; https://orcid.org/0000-0002-0352-8818; https://orcid.org/0000-0001-6908-3412; https://orcid.org/0000-0003-0987-1980; 27445314; AAK-5370-2021; HOC-5611-2023; AAK-5399-2021; AAC-5654-2020; S-8384-2016
    Background: Further research is required for evaluating the use of ADC histogram analysis in more advanced stages of cervical cancer treated with definitive chemoradiotherapy (CRT). Purpose: To investigate the utility of apparent diffusion coefficient (ADC) histogram derived from diffusion-weighted magnetic resonance images in cervical cancer patients treated with definitive CRT. Material and Methods: The clinical and radiological data of 50 patients with histologically proven cervical squamous cell carcinoma treated with definitive CRT were retrospectively analyzed. The impact of clinicopathological factors and ADC histogram parameters on prognostic factors and treatment outcomes was assessed. Results: The mean and median ADC values for the cohort were 1.043 +/- 0.135 x 10(-3) mm(2)/s and 1.018 x 10(-3) mm(2)/s (range, 0.787-1.443 x 10(-3) mm(2)/s). The mean ADC was significantly lower for patients with advanced stage (>= IIB) or lymph node metastasis compared with patients with stage < IIB or no lymph node metastasis. The mean ADC, 75th percentile ADC (ADC75), 90th percentile ADC (ADC90), and 95th percentile ADC (ADC95) were significantly lower in patients with tumor recurrence compared with patients without recurrence. In multivariate analysis, tumor size, ADC75 and ADC95 were independent prognostic factors for both overall survival and disease-free survival. Conclusion: ADC histogram parameters could be markers for disease recurrence and for predicting survival outcomes. ADC75, ADC90, and ADC95 of the primary tumor were significant predictors of disease recurrence in cervical cancer patients treated with definitive CRT.