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

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    Treatment Outcomes of Breast Cancer Liver Metastasis Treated with Stereotactic Body Radiotherapy
    (2018) Onal, Cem; Guler, Ozan Cem; Yildirim, Berna Akkus; https://orcid.org/0000-0002-2742-9021; https://orcid.org/0000-0001-6908-3412; https://orcid.org/0000-0001-6661-4185; 30296648; HOC-5611-2023; AAC-5654-2020; V-5717-2017
    Background: To assess the outcomes of breast cancer liver metastasis (BCLM) treated with stereotactic body radiotherapy (SBRT) and systemic treatment. Materials and methods: Patients with oligometastasis at the time of liver metastasis (LM) or who became oligometastatic (<= 5 metastases) after systemic treatment were assessed. Twenty-nine liver metastatic lesions were treated with a total of 54 Gy delivered in 3 fractions. The local control (LC), overall survival (OS), and progression-free survival (PFS) rates were calculated using Kaplan-Meier analyses. Results: A total of 22 patients with 29 liver metastatic lesions treated with liver SBRT between April 2013 and September 2017 were retrospectively analyzed. After a median follow-up time of 16.0 months (range 4.4-59.4 months), 18 patients (82%) had disease recurrence, median of 7.4 months (range 1.0-27.9 months) after completion of liver SBRT. The 1- and 2-year OS rates were 85% and 57%, and the 1- and 2-year PFS rates were 38% and 8%, respectively. The 1- and 2-year LC rates were 100% and 88%, respectively. No significant prognostic factors, including disease extension, size of metastasis, number of liver metastasis and timing of liver metastasis, hormonal status affecting OS, PFS and LC were found. No patients experienced Grade 4 or 5 toxicity; furthermore, only one patient experienced rib fracture 6 months after completion of treatment, and one patient had a duodenal ulcer. Conclusion: This study is the first to evaluate the feasibility of SBRT to BCLM patients. Liver SBRT is a conservative approach with excellent LC and limited toxicities. (C) 2018 Elsevier Ltd. All rights reserved.
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    Prognostic Significance Of Albumin And Globulin Levels In Cervical Cancer Patients Treated With Chemoradiotherapy
    (2023) Oymak, Ezgi; Guler, Ozan Cem; Onal, Cem; https://orcid.org/0000-0002-2742-9021; 36356983; D-5195-2014
    ObjectiveAlbumin-globulin ratio or albumin-globulin score predict survival in many cancers, but there are few data on cervical cancer patients. This study examined whether pre-treatment albumin and globulin levels, as well as the albumin-globulin ratio and albumin-globulin score, can predict treatment outcomes in cervical cancer patients undergoing definitive chemoradiotherapy. MethodsA retrospective analysis of cervical cancer patients treated between January 2006 and July 2014 was performed. Receiver operating characteristic curves for serum albumin and globulin levels, as well as albumin-globulin ratio values, were generated in order to determine the cut-off values for these parameters and to predict their sensitivity and specificity for predicting recurrence and survival. Univariate and multivariate analyses were used to identify prognostic factors for overall survival and progression-free survival. ResultsA total of 139 patients were included. The median follow-up time was 11.5 years. The 5- and 10-year overall survival rates were 54.7% and 39.3%, while the 5- and 10-year progression-free survival rates were 48.9% and 36.4%, respectively. The optimal cut-off points were 3.79 g/dL for albumin, 3.27 g/dL for globulin, and 1.56 for albumin-globulin ratio. In the univariate analysis, significant prognostic factors for overall survival and progression-free survival were albumin-globulin ratio, albumin-globulin score, patient age, International Federation of Gynecology and Obstetrics (FIGO) stage, tumor size, lymph node metastasis, and treatment response. Older age, advanced stage, low albumin-globulin ratio, albumin-globulin score of 2, and inadequate treatment response had poor overall survival and progression-free survival in multivariable analysis. However, serum albumin and globulin levels were not found to be a significantly predictive factor for survival. There was a significant correlation between albumin levels, globulin levels, tumor size, stage, lymph node metastasis, and treatment response. ConclusionsPre-treatment albumin-globulin ratio and albumin-globulin score are useful prognostic factors in patients with cervical squamous cell cancer treated with definitive chemoradiotherapy, and may be suitable biomarkers for predicting treatment outcomes.
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    Treatment Outcomes of Stereotactic Body Radiotherapy in Patients with Synchronous and Metachronous Oligometastatic Renal Cell Carcinoma
    (2023) Guler, Ozan Cem; Oymak, Ezgi; Hurmuz, Pervin; Yavas, Guler; Tilki, Burak; Yavas, Cagdas; Ozyigit, Gokhan; Onal, Cem; 0000-0002-2742-9021; 36455527; D-5195-2014
    Introduction: The aim of this study was to investigate the clinical outcomes of metastasis-directed therapy (MDT) using stereotactic body radiotherapy (SBRT) in patients with synchronous or metachronous oligometastatic renal cell carcinoma (RCC). Methods: The clinical data of 87 patients with 138 lesions who received MDT between February 2008 and January 2019 were retrospectively analyzed. All patients had <= 5 metastasis at diagnosis (synchronous) or during progression (metachronous) and were treated with SBRT for their metastasis. The primary endpoints were local control (LC) and progression-free survival (PFS). The secondary endpoint was overall survival (OS). Results: Median follow-up was 20.4 months for entire cohort and 27.2 months for survivors. Synchronous oligometastatic disease was observed in 35 patients (40.2%), and 52 patients (59.8%) had metachronous disease. Seventy-two patients (82.8%) received systemic treatment synchronously or after MDT, while 15 patients (17.2%) did not receive any systemic treatment. The 1- and 2-year OS rates were 79.4% and 58.1%, respectively, and the 1- and 2-year PFS rates were 58.6% and 15.1%, respectively. The 1- and 2-year LC rates per lesion were 96.6% and 91.4%, respectively. There were no significant differences in survival between patients with synchronous oligometastasis and those with metachronous oligometastasis. All disease progressions were observed at a median time of 31.6 months (range: 1.9-196.9 months) after the completion of SBRT. Patients with solitary oligometastasis had significantly better OS compared to patients with >1 metastasis (p = 0.04). No patients experienced grade 3 or higher acute or late toxicities. Conclusion: SBRT is a successful treatment for oligometastatic RCC patients due to its excellent LC and minimal toxicity profile. There were no statistically significant survival differences between patients with synchronous and metachronous oligometastasis. Patients with solitary oligometastasis outlived their counterparts.
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    The prognostic value of mean apparent diffusion coefficient measured with diffusion-weighted magnetic resonance image in patients with prostate cancer treated with definitive radiotherapy
    (2022) Onal, Cem; Erbay, Gurcan; Guler, Ozan Cem; Oymak, Ezgi; 35753556
    Purpose: To assess the correlation between initial tumor apparent diffusion coefficient (ADC) values and clinicopathological parameters in prostate cancer (PCa) patients treated with definitive radiotherapy (RT). Additionally, the prognostic factors for freedom from biochemical failure (FFBF) and progressionfree survival (PFS) in this patient cohort were analyzed. Materials and methods: The clinical data of 503 patients with biopsy-confirmed PCa were evaluated retrospectively. All patients had clearly evident tumors on diffusion-weighted magnetic resonance imaging (DW-MRI) for ADC values. Univariable and multivariable analyses were used to determine prognostic factors for FFBF and PFS. Results: The median follow-up was 72.9 months. The 5-year FFBF and PFS rates were 93.2% and 86.2%, respectively. Significantly lower ADC values were found in patients with a high PSA level; advanced clinical stage; higher ISUP score, and higher risk group than their counterparts. Receiver operating characteristic (ROC) curve analysis revealed an ADC cut-off value of 0.737 x 10-3 mm2/sec for tumor recurrence. Patients who progressed had a lower mean ADC value than those who did not (0.712 +/- 0.158 vs. 1.365 +/- 0. 227 x 10-3 mm2/sec; p < 0.001). There was a significant difference in 5-year FFBF (96.3% vs. 90%; p < 0.001) and PFS rates (83.8% vs. 73.5%; p = 0.002) between patients with higher and lower mean ADC values. The FFBF and PFS were found to be correlated with tumor ADC value and ISUP grades in multivariable analysis. Additionally, older age was found to be a significant predictor of worse PFS. Conclusions: Lower ADC values were found in patients with high-risk characteristics such as a high serum PSA level, stage or grade of tumor, or high-risk disease, implying that ADC values could be used to predict prognosis. Lower ADC values and higher ISUP grades were associated with an increased risk of BF and progression, implying that treatment intensification may be required in these patients. (c) 2022 Elsevier B.V. All rights reserved. Radiotherapy and Oncology 173 (2022) 285-291
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    Oncological outcomes of squamous cell carcinoma of the cervical esophagus treated with definitive (chemo-)radiotherapy: a systematic review and meta-analysis. In regard to De Virgilio et al
    (2022) Guler, Ozan Cem; Onal, Cem; 0000-0002-2742-9021; 35697858; D-5195-2014
    This is a significant study that shows that definitive chemo-radiotherapy is an effective treatment option for cervical esophageal squamous cell carcinoma. We are curious, though, whether local control has any effect on survival.
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    Bone Only Oligometastatic Renal Cell Carcinoma Patients Treated with Stereotactic Body Radiotherapy: A Multi Institutional Study
    (2022) Onal, Cem; Guler, Ozan Cem; Hurmuz, Pervin; Yavas, Guler; Tilki, Burak; Oymak, Ezgi; Yavas, Cagdas; Ozyigit, Gokhan; 0000-0002-2742-9021; 35695908; D-5195-2014
    Purpose This study aimed to analyze the prognostic factors associated with overall survival (OS) and progression-free survival (PFS) in patients with bone-only metastatic renal cell carcinoma (RCC) who have five or fewer lesions treated with stereotactic body radiotherapy (SBRT). Methods The clinical data of 54 patients with 70 bone metastases undergoing SBRT treated between 2013 and 2020 with a dose of at least 5 Gy per fraction and a biologically effective dose (BED) of at least 90 Gy were retrospectively evaluated. Results The majority of lesions were located in the spine (57.4%) and had only one metastasis (64.8%). After a median follow-up of 22.4 months, the 1- and 2-year OS rates were 84.6% and 67.3%, respectively, and median OS was 43.1 months. The 1- and 2-year PFS rates and median PFS were 63.0%, 38.9%, and 15.3 months, respectively. In SBRT-treated lesions, the 1-year local control (LC) rate was 94.9%. Age, metastasis localization, and number of fractions of SBRT were significant prognostic factors for OS in univariate analysis. In multivariate analysis, patients with spinal metastasis had better OS compared to their counterparts, and patients who received single-fraction SBRT had better PFS than those who did not. No patient experienced acute or late toxicities of grade 3 or greater. Conclusion Despite excellent LC at the oligometastatic site treated with SBRT, disease progression was observed in nearly half of patients 13 months after metastasis-directed local therapy, particularly as distant disease progression other than the treated lesion, necessitating an effective systemic treatment to improve treatment outcomes.
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    Re: Androgen deprivation therapy and radiotherapy in intermediate risk prostate cancer: A randomized phase III trial
    (2022) Guler, Ozan Cem; Onal, Cem; 0000-0002-2742-9021; 35282967; D-5195-2014
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    The Impact Of Serum Albumin-To-Alkaline Phosphatase Ratio In Cervical Cancer Patients Treated With Definitive Chemoradiotherapy
    (2022) Onal, Cem; Gultekin, Melis; Yavas, Guler; Oymak, Ezgi; Sari, Sezin Yuce; Guler, Ozan Cem; Yigit, Ecem; Yildiz, Ferah; 35653776
    We retrospectively analysed the prognostic significance of serum albumin, alkaline phosphatase (ALP) and albumin to ALP ratio (AAPR) and other prognostic factors affecting the overall survival (OS) and progression-free survival (PFS) in 200 cervical cancer patients treated with definitive chemoradiotherapy (CRT). The prognostic factors for OS and DFS, in addition to the predictive factors of albumin, ALP and AAPR, were investigated. Older age, lymph node metastasis, non-complete response (CR) to treatment and low serum albumin levels emerged as predictors of poor OS and PFS in multivariate analysis. However, with a cut-off value of 0.51, AAPR was not a significant prognostic factor of survival in multivariable analysis. There were no significant differences in clinicopathological factors between patients with low and high AAPR, except for lymph node metastasis, where lymph node metastasis rate was significantly higher in patients with a low AAPR compared to those with a high AAPR. Patients with CR had a significantly higher serum albumin level and AAPR compared to patients without CR. The pre-treatment serum albumin level was independent predictive for survival; therefore, it could be a suitable biomarker to guide systemic therapy and predict patient outcomes. Impact Statement What is already known on this subject? Two major determinants of tumour progression are nutritional status and inflammation. The albumin-to-alkaline phosphatase ratio (AAPR), which was originally proposed as a marker for nutritional status and immune response, was recently discovered to be a prognostic factor for various cancer types. However, its utility in the treatment of cervical cancer has not been established. What do the results of this study add? Low serum albumin levels were associated with a significantly shorter OS and PFS in cervical cancer patients treated definitively with CRT. AAPR, on the other hand, was not a significant prognostic factor for survival with a cut-off value of 0.51. Regional lymph node metastasis was significantly more common in patients with a low AAPR than in those with a high AAPR. What are the implications of these findings for clinical practice and/or further research? Patients with multiple clinicopathological risk factors and low serum albumin levels had an increased risk of disease recurrence and a poorer prognosis, highlighting the importance of additional adjuvant treatment strategies in these patients. Due to the preliminary nature of our findings, additional research is required to corroborate them.
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