Browsing by Author "Guler, Ozan Cem"

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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.
Clinical characteristics of relapsed ovarian cancer patients with striking response to the bevacizumab at first relapse
(2020) Kose, Fatih; Alemdaroglu, Songul; Mertsoylu, Huseyin; Besen, Ali Ayberk; Guler, Ozan Cem; Simsek, Seda Yuksel; Erbay, Gurcan; Onal, Cem; Celik, Husnu; 0000-0002-2742-9021; 0000-0003-4335-6659; 0000-0001-6908-3412; 0000-0002-0156-5973; 0000-0002-7862-0192; 0000-0002-1932-9784; D-5195-2014; AAI-8400-2021; AAC-5654-2020; G-4827-2016; AAD-6910-2021; M-9530-2014
Background: Ovarian cancer is fifth leading cause of the cancer related death in women. Platin based doublet regimen plus bevacizumab is standard treatment in relapse. The primary aim of this study is to define clinicopathological characteristics of the relapsed ovarian cancer who derived unexpectedly long benefit from bevacizumab treatment. Methods: Total number of 106 patients with relapsed ovarian cancer and treated with bevacizumab (bevacizumab is not reimbursed as a part of adjuvant treatment in Turkey) on their first relapse were included. For the purpose of the study, the patients were placed into two groups, Group A and B, selected on the basis of the rate of PFS 1 (time between first day of adjuvant chemotherapy and first radiological progression) to PFS 2 (time between first day of second line treatment and second radiological progression). The patients included into Group A if PFS 1 greater than PFS 2 and Group B vice versa. Results: Group A and B were consisted of 67 (63%) and 39 (37%) patients. At a median follow-up of 32.1 months (5.3-110.8), 56 (52.8%) patients were died. Significant number of patients (78.4%) treated with primary surgery without neoadjuvant treatment and 59 (57.8%) out of the 102 patients had debulking surgery when their cancer relapsed. PFS 1 and 2 were estimated as 16.5 mo (14.1-18.9) vs. 13.7 mo (9.9-17.5) and 13.4 mo (8.0-18.6) vs. 29.7 mo (21.5-38.0) in group A and B, respectively (p < 0.001 and p < 0.001). Only parameter that show significant difference between groups was the rate of platin resistant patients; Group A: 13 (19.4%) out of 67 patients vs. Group B: 15 (38.6%) out of 39 patients with ap value of 0.041. Binary logistic regression indicates PFS1 is significant inverse predictor (shorter PFS-1 means greater chance of being in group B) of entering Group B [Chi-Square = 16.5, df = 6 and p = 0.011 (< 0.05)]. PFS1 is significant at the 5% level [ PFS1 wald = 4.33,p = 0.038 (p < 0.05)]. In multivariate analysis, cox-regression proportional hazard, cytoreductive surgery at second relapse (yes or no) (p: 0.028; HR: 0.3, 0.02-0.7, 95% CI) showed significant effect on PFS-2. On the other hand, platin resistance (< 6 mos; yes or no) (p: 0.04; HR: 4.0, 1.1-14.4, 95% CI) and secondary surgery outcome (no visible vs. visible) (p: 0.003; HR: 0.2, 0.07-0.58, 95% CI) showed significant effect on OS. Bevacizumab related adverse effects with greater than grad 3 detected in 13 (15%) and 10 (25%) in group A and B (p: 0.77). Conclusions: Our findings indicate that bevacizumab produced strikingly high PFS (over 24 months) in significant portion of relapsed ovarian cancer patients whom were mostly platin resistant cases with short PFS-1. This gain specifically achieved in patients who had aggressive secondary surgery with no-visible surgical outcome.
The clinical outcomes of ovarian cancer in patients with brain metastasis
(2021) Simsek, Seda Yuksel; Guler, Ozan Cem; Durdag, Gulsen Dogan; Sari, Sezin Yuce; Gultekin, Melis; Yildiz, Ferah; Celik, Husnu; Erbay, Gurcan; Onal, Huseyin Cem; 0000-0003-3191-9776; AAK-7016-2021
Objective: To present the clinical characteristics and treatment outcomes of patients with ovarian cancer with brain metastasis. Methods: This study was designed as a retrospective observational study. Patients' data were obtained from hospital records. Patients who were diagnosed with brain metastatic ovarian cancer in two tertiary referral centers between 2012 and 2020 were included in the study. Results: In total, there were 56 patients diagnosed as having brain metastatic ovarian cancer. The median age was 56 years, 91% of patients were at an advanced stage at initial diagnosis. The median time from the initial diagnosis to brain metastasis was 34.0 months. Sixty-seven percent of patients were determined as having multiple brain metastatic lesions. Whole brain radiotherapy (WBRT) , stereotactic radiosurgery (SRS) and combined approach were utilized as primary treatment. The 1 and 2-year survival rates were 38% and 17%, respectively. Patient age and tumor histology were found to be significant prognostic factors that impact the survival in univariate analyses. The 1-year survival of patients aged younger than 55 years was 49.2%, and 28.2% for patients aged over 55 years (p = 0.04). Patients with nonserous histology had significantly longer one year overall survival compared to serous histology (61.4% vs 29.8%) (p= 0.01). Conclusion: The brain is one of the rarest locations for ovarian cancer metastasis. Radiotherapeutic approaches are the mainstay of treatment but survival rates are low. Age and tumor histology were determined as significant parameters that affected survival rates.
Clinical parameters and nomograms for predicting lymph node metastasis detected with Ga-68-PSMA-PET/CT in prostate cancer patients candidate to definitive radiotherapy
(2021) Onal, Cem; Ozyigit, Gokhan; Oymak, Ezgi; Guler, Ozan Cem; Hurmuz, Pervin; Tilki, Burak; Reyhan, Mehmet; Tuncel, Murat; Akyol, Fadil; 0000-0002-2742-9021; 33949694; D-5195-2014
Background Defining the extent of disease spread with imaging modalities is crucial for therapeutic decision-making and definition of treatment. This study aimed to investigate whether clinical parameters and nomograms predict prostate-specific membrane antigen (PSMA)-positive lymph nodes in treatment-naive nonmetastatic prostate cancer (PC) patients. Materials and Methods The clinical data of 443 PC patients (83.3% high-risk and 16.7% intermediate-risk) were retrospectively analyzed. Receiver operating characteristic (ROC) curves with areas under the curve (AUC) were generated to evaluate the accuracy of clinical parameters (prostate-specific antigen [PSA], T stage, Gleason score [GS], International Society of Urological Pathology [ISUP] grade) and nomograms (Roach formula [RF], Yale formula [YF], and a new formula [NF]) in predicting lymph node metastasis. The AUCs of the various parameters and clinical nomograms were compared using ROC and precision-recall (PR) curves. Results A total of 288 lymph node metastases were identified in 121 patients (27.3%) using Ga-68-PSMA-11-positron emission tomography (PET)/computed tomography (CT). Most PSMA-avid lymph node metastases occurred in external or internal iliac lymph nodes (142; 49.3%). Clinical T stage, PSA, GS, and ISUP grade were significantly associated with PSMA-positive lymph nodes according to univariate logistic regression analysis. The PSMA-positive lymph nodes were more frequently detected in patients with PSA >20 ng/ml, GS >= 7 or high risk disease compared to their counterparts. The clinical T stage, serum PSA level, GS, and ISUP grade showed similar accuracy in predicting PSMA-positive metastasis, with AUC values ranging from 0.675 to 0.704. The median risks for PSMA-positive lymph nodes according to the RF, YF, and NF were 31.3% (range: 12.3%-100%), 22.3% (range: 4.7%-100%), and 40.5% (range: 12.3%-100%), respectively. The AUC values generated from ROC and PR curve analyses were similar for all clinical nomograms, although the RF and YF had higher accuracy compared to NF. Conclusion The clinical T stage, PSA, GS, and ISUP grade are independent predictors of PSMA-positive lymph nodes. The RF and YF can be used to identify patients who can benefit from Ga-68-PSMA-11 PET/CT for the detection of lymph node metastasis. Together with nomograms, Ga-68-PSMA-11 PET/CT images help to localize PSMA-positive lymph node metastases and can thus assist in surgery and radiotherapy planning.
Comparison of Helical and TomoDirect Techniques with Simultaneous Integrated Boost in Early Breast Cancer Patients
(REPORTS OF PRACTICAL ONCOLOGY AND RADIOTHERAPY, 2023) Onal, Cem; Bozca, Recep; Oymak, Ezgi; Guler, Ozan Cem
Background: The aim of the study was to perform dosimetric comparisons of helical (H) and TomoDirect (TD) plans for whole-breast irradiation (WBI) with simultaneous integrated boost (SIB) in early-stage breast cancer patients undergoing breast conserving surgery.Materials and methods: Fifty patients, 25 with left-side and 25 with right-side tumors, were determined for a treatment planning system for a total dose of 50.4Gy in 1.8Gy per fraction to WBI, with a SIB of 2.3Gy per fraction delivered to the tumor bed. The planning target volume (PTV) doses and the conformity (CI) and homogeneity indices (HI) for PTV(breast )and PTVboost, as well as organ-at-risk (OAR) doses and treatment times, were compared between the H and TD plans.Results: All plans met the PTV coverage criteria for the H plan, except for mean V107 of PTVbreast for TD plan. The H plan yielded better homogeneity and conformity of dose distribution compared to the TD plan. The ipsilateral mean lung doses were not significantly different between the two plans. The TD plans is advantageous for mean doses to the heart, contralateral breast and lung, spinal cord, and esophagus than the H plans. In both the H and TD plans, the right-sided breast patients had lower heart dose parameters than the left-sided breast patients. The TD plan is superior to the H plan in sparing the contralateral breast and lung by decreasing low-dose volumes.Conclusions: While the OAR dose advantages of TD are appealing, shorter treatment times or improved dose homogeneity and conformity for target volume may be advantageous for H plan.
Comparison of Involved Field Radiotherapy versus Elective Nodal Irradiation in Stage IIIB/C Non-Small-Cell Lung Carcinoma Patients Treated with Concurrent Chemoradiotherapy: A Propensity Score Matching Study
(2020) Topkan, Erkan; Ozdemir, Yurday; Guler, Ozan Cem; Kucuk, Ahmet; Besen, Ali Ayberk; Mertsoylu, Huseyin; Sezen, Duygu; Akdemir, Eyub Yasar; Sezer, Ahmet; Bolukbasi, Yasemin; Pehlivan, Berrin; Selek, Ugur; 0000-0002-1932-9784; 0000-0001-6908-3412; 0000-0002-2218-2074; 0000-0002-6445-1439; 0000-0001-8120-7123; 0000-0002-7862-0192; 32952557; M-9530-2014; AAC-5654-2020; AAG-5629-2021; AAD-2667-2020; AAG-2213-2021; AAD-6910-2021
Background. We retrospectively compared the incidence of isolated elective nodal failure (IENF) and toxicity rates and survival outcomes after elective nodal irradiation (ENI) versus involved-field RT (IFRT) by employing the propensity score matching (PSM) methodology in stage IIIB/C inoperable non-small-cell lung cancer (NSCLC) patients treated with definitive concurrent chemoradiotherapy (C-CRT).Methods. Our PSM examination included 1048 stage IIIB/C NSCLC patients treated with C-CRT from January 2007 to December 2016: a total dose of 66 Gy (2 Gy/fraction) radiotherapy and 1-3 cycles of platinum-based doublet chemotherapy concurrently. The primary and secondary endpoints were the IENF and toxicity rates and survival outcomes after ENI versus IFRT, respectively. Propensity scores were calculated for each group to adjust for confounding variables and facilitate well-balanced comparability by creating 1 : 1 matched study groups.Results. The median follow-up was 26.4 months for the whole study accomplice. The PSM analysis unveiled 1 : 1 matched 646 patients for the ENI (N = 323) and IFRT (N = 323) cohorts. Intergroup comparisons discovered that the 5-year isolated ENF incidence rates (3.4% versus 4.3%;P=0.52) and median overall survival (25.2 versus 24.6 months;P=0.69), locoregional progression-free survival (15.3 versus 15.1 months;P=0.52), and progression-free survival (11.7 versus 11.2 months;P=0.57) durations were similar between the ENI and IFRT cohorts, separately. However, acute grade 3-4 leukopenia (P=0.0012), grade 3 nausea-vomiting (P=0.006), esophagitis (P=0.003), pneumonitis (P=0.002), late grade 3-4 esophageal toxicity (P=0.038), and the need for hospitalization (P<0.001) were all significantly higher in the ENI than in the IFRT group, respectively.Conclusion. Results of the present large-scale PSM cohort established the absence of meaningful IENF or survival differences between the IFRT and ENI cohorts and, consequently, counseled the IFRT as the elected RT technique for such patients since ENI increased the toxicity rates.
Concurrent versus sandwich treatment in adjuvant treatment in high risk operated gastric cancer: A single center experience
(2020) Sezer, Ahmet; Akkus, Berna; Guler, Ozan Cem; Onal, Huseyin Cem; Sumbul, Ahmet Taner; 0000-0001-6908-3412; 0000-0002-2742-9021; 33277854; AAC-5654-2020; D-5195-2014
Purpose: In this study we compared postoperative early vs sandwich chemoradiotherapy in operated stage IIA-IIIC gastric cancer patients in terms of effectiveness and outcome. Methods: The data of 201 gastric cancer patients treated in the same center between December 2006 and June 2017 were retrospectively evaluated. One hundred forty nine patients who were eligible for the study criteria were divided into two groups according to the postoperative treatment modality. The first group included 85 patients who were given chemoradiotherapy simultaneously (ETG) and the second group icluded 64 patients who received sandwich (chemotherapychemoradiotherapy-chemotherapy) (STG) treatment. Overall survival (OS) and disease-free survival (DFS) were evaluated as primary endpoints. Results: The median follow-up time for all patient groups was 26.7 months (1.3-136.5 months). Adjuvant chemotherapy and radiotherapy were initiated concurrently in patients receiving concomitant therapy. Half of the planned chemotherapy, then chemoradiotherapy and then the remaining chemotherapy treatments were given to the sandwich treatment group. A total of 50.4 Gy radiotherapy was given to the concurrent chemoradiotherapy group and a total of 45 Gy radiotherapy to the group receiving the sandwich treatment. OS was 30.6 months (23.7-37.5) in all groups, 30.4 months (23.7-35.0) in concurrent therapy (ETG) and 35.6 months (26.3-45) in sandwich therapy (STG) (p=0.73). DFS was 26.6 months (21.3-32.0) in all groups and 24.5 months (18.1-31.0) in the group receiving ETG, 32.5 months (22.242.8) in STG. (p=0.46). The most common grade 3 and above toxicities were; acute upper gastrointestinal toxicity (19.1% in ETG vs. 9.0% in STG, p=0.01) and hematological toxicity (31.8% in ETG vs. 13.9% in STG; p=0.002). Early cessation of treatment was similar in both groups. In multivariate analysis, female gender (p=0.01), stage III disease, grade III disease were seen as negative predictive factors for overall survival. In DFS multivariate analysis, there was no difference between the groups in terms of gender, T stage, N stage, and AJCC stage. Conclusion: In this study, superiority of sandwich treatment over concurrent treatment was observed in patients with operated stage IIB-IIIC gastric cancer, but the difference was not statistically significant. If this study is performed in larger patient series, the difference of sandwich treatment may become meaningful.
Definitive Chemoradiation Therapy Following Surgical Resection or Radiosurgery Plus Whole-Brain Radiation Therapy in Non-Small Cell Lung Cancer Patients With Synchronous Solitary Brain Metastasis: A Curative Approach
(2014) Parlak, Cem; Mertsoylu, Huseyin; Guler, Ozan Cem; Onal, Cem; Topkan, Erkan; https://orcid.org/0000-0001-6170-0383; https://orcid.org/0000-0002-1932-9784; https://orcid.org/0000-0001-6908-3412; https://orcid.org/0000-0002-2742-9021; https://orcid.org/0000-0001-8120-7123; 24495594; B-3671-2014; M-9530-2014; AAC-5654-2020; HOC-5611-2023; AAG-2213-2021
Purpose/Objectives: The aim of this study was to evaluate the impact of definitive thoracic chemoradiation therapy following surgery or stereotactic radiosurgery (SRS) and whole-brain radiation therapy (WBRT) on the outcomes of patients with non-small cell lung cancer (NSCLC) with synchronous solitary brain metastasis (SSBM). Methods and Materials: A total of 63 NSCLC patients with SSBM were retrospectively evaluated. Patients were staged using positron emission tomography-computed tomography in addition to conventional staging tools. Thoracic radiation therapy (TRT) with a total dose of 66 Gy in 2 Gy fractions was delivered along with 2 cycles of cisplatin-based chemotherapy following either surgery plus 30 Gy of WBRT (n = 33) or SRS plus 30 Gy of WBRT (n = 30) for BM. Results: Overall, the treatment was well tolerated. All patients received planned TRT, and 57 patients (90.5%) were also able to receive 2 cycles of chemotherapy. At a median follow-up of 25.3 months (7.1-52.1 months), the median months of overall, locoregional progression-free, neurological progression-free, and progression-free survival were 28.6, 17.7, 26.4, and 14.6, respectively. Both univariate and multivariate analyses revealed that patients with a T1-T2 thoracic disease burden (P = .001), a nodal stage of N0-N1 (P = .003), and no weight loss (P = .008) exhibited superior survival. Conclusions: In the present series, surgical and radiosurgical treatments directed toward SSBM in NSCLC patients were equally effective. The similarities between the present survival outcomes and those reported in other studies for locally advanced NSCLC patients indicate the potentially curative role of definitive chemoradiation therapy for highly selected patients with SSBM. (C) 2014 Elsevier Inc.
Definitive Chemoradiotherapy in Elderly Cervical Cancer Patients: A Multiinstitutional Analysis
(2017) Guler, Ozan Cem; Sari, Sezin Yuce; Birgi, Sumerya Duru; Gultekin, Melis; Yildiz, Ferah; Onal, Cem; https://orcid.org/0000-0002-2742-9021; 28604459; D-5195-2014
Objective The aim of the study was to investigate the prognostic factors for survival and treatment-related toxicities in older (65 years) cervical cancer patients treated with definitive chemoradiotherapy. In addition, we sought to compare the outcomes between the older elderly (75 years) and their younger old counterparts (age, 65-74 years). Materials and Methods We retrospectively reviewed medical records from 269 biopsy-proven nonmetastatic cervical cancer patients treated with external radiotherapy and intracavitary brachytherapy at the departments of radiation oncology in 2 different universities. The prognostic factors for survival, local control, and distant metastasis (DM) were analyzed. Results The median follow-up time was 38.8 months (range, 1.5-175.5 months) for the entire cohort and 70.0 months (range, 6.1-175.7 months) for survivors. The 2- and 5-year overall survival (OS), disease-free survival (DFS), and cause-specific survival rates were 66% and 42%, 63% and 39%, and 72% and 55%, respectively. Patients 75 years or older showed significantly worse OS compared with patients aged 65 to 74 years but showed no significant difference in DFS. The 2- and 5-year local control rates were 86% and 71%, respectively. The incidences of DMs at 2 and 5 years were 22% and 30%, respectively. In multivariate analysis, vaginal infiltration and lymph node metastasis were predictive of OS, DFS, local recurrence, and DM. Concomitant chemotherapy was predictive of OS, DFS, and local recurrence, and larger tumor (>4 cm) was a significant prognostic factor for local recurrence. None of the patients had toxicity that necessitated the discontinuation of radiotherapy. All patients were evaluable for acute toxicity, and no grade higher than 3 adverse events occurred during external beam radiation therapy or brachytherapy. Conclusions Although age limited the delivery of aggressive treatment, concurrent chemoradiotherapy in elderly patients associated with improved outcomes similar as in younger counterparts without increasing serious acute and late toxicities.
Definitive concurrent chemoradiotherapy outcomes in Stage IIIB nonsmall cell lung cancer patients younger than 45 years: A retrospective analysis of 145 patients
(2020) Topkan, Erkan; Guler, Ozan Cem; Ozdemir, Yurday; 0000-0001-6908-3412; 0000-0002-2218-2074; 0000-0001-8120-7123; 32930115; AAC-5654-2020; AAG-5629-2021; AAG-2213-2021
Purpose: To assess the survival outcomes and prognostic factors of young (<= 45 years) Stage IIIB nonsmall cell lung cancer (NSCLC) patients treated with definitive concurrent chemoradiotherapy (C-CRT). Materials and Methods: Medical records of 145 Stage IIIB NSCLC patients (<= 45 years) who received 60-66 Gy thoracic radiotherapy and concurrent 1-3 cycles of cisplatin-based doublet chemotherapy were retrospectively evaluated. The primary endpoint was overall survival (OS), while locoregional progression-free survival (LRPFS), progression-free survival (PFS), and evaluation of potential prognostic factors constituted the secondary endpoints. Results: At median 21.6 months (range: 7.3-62.5) of follow-up, the median and 4-year survival estimates were 24.8 months and 24.2% for OS, 15.7 months and 18.9%, for LRPFS and 12.0 months and 11.2% for PFS, respectively. On univariate analyses, among all factors, the smaller tumor size (<= 7.0 cm; P = 0.03), lower T-stage (T1-T2; P = 0.02), lower N-stage (N2; P = 0.01), absence of anemia before C-CRT (hemoglobin [Hb] >= 12 g/dL; P < 0.001), and lower/no pretreatment weight loss (WL 5%; P < 0.001) were found to be associated significantly with longer median OS durations, which also retained their independent significance on multivariate analyses, except for tumor size category. Conclusions: The encouraging median 24.8 months OS duration observed here in young NSCLC patients accords well with the results of recent landmark locally advanced NSCLC series without age stratification. Other than the well-established T and N stages, extra exhibit of superior OS in patients with initial Hb 12 g/dL and <= 5% WL levels suggests a noteworthy prognostic role for these two latter variables in the stratification of such patients.
Dosimetric comparison of vaginal vault brachytherapy vs applicator-guided stereotactic body radiotherapy with volumetric modulated arc therapy and helical tomotherapy for endometrium cancer patients
(2019) Yildirim, Berna Akkus; Dolek, Yemliha; Guler, Ozan Cem; Arslan, Gungor; Onal, Cem; 0000-0001-6908-3412; 0000-0001-6661-4185; 0000-0002-2742-9021; 30551844; AAC-5654-2020; D-5195-2014
We performed this dosimetric study to compare a nonstandard volumetric modulated arc therapy (VMAT) and helical tomotherapy (HT) techniques with high-dose rate (HDR) brachytherapy (BRT) plan of vaginal vault in patients with postoperative endometrial cancer (EC). Twelve postoperative patients with early stage EC were included in this study. Three plans were performed for each patient; dosimetric and radiobiological comparisons were made using dose-volume histograms and equivalent dose for determining the planning target volume (PTV) coverages in brachytherapy and external beam radiotherapy, and organs-at-risk (OARs) doses between three different delivery techniques. All the plans achieved adequate dose coverage for PTV; however, the VMAT plan yielded better dose conformity, and the HT plan showed better homogeneity for target volume. With respect to the OARs, the bladder D-2cc was significantly lower in the BRT plan than in the VMAT and HT plans, with the highest bladder D-2cc value being observed in the HT plan. However, no difference was observed in the rectum D-2cc of the three plans. Other major advantages of the BRT plan over the VMAT and HT plans were the relatively lower body integral doses and femoral head doses as well as the fact that the integral doses were significantly lower in the BRT plan than in the VMAT and HT plans. This is the first dosimetric comparison of vaginal vault treatment for EC with BRT, VMAT, and HT plans. Our analyses showed the feasibility of stereotactic body radiotherapy technique as an alternative to HDR-BRT for postoperative management of EC patients. (C) 2018 American Association of Medical Dosimetrists. Published by Elsevier Inc. All rights reserved.
Effect of Adjuvant Extended Temozolamide Treatment in Survival of Patients with Glioblastoma Multiforme
(2018) Yildirim, Berna Akkus; Sumbul, Ahmet Taner; Topkan, Erkan; Ozdemir, Yurday; Besen, Ali Ayberk; Guler, Ozan Cem; Sedef, Ali Murat; Onal, Cem; https://orcid.org/0000-0001-6661-4185; https://orcid.org/0000-0002-5573-906X; https://orcid.org/0000-0001-8120-7123; https://orcid.org/0000-0002-2218-2074; https://orcid.org/0000-0002-7862-0192; V-5717-2017; D-4793-2014; AAG-2213-2021; AAG-5629-2021; AAD-6910-2021; HOC-5611-2023
Purpose: The aim of this retrospective cohort study was to evaluate the prognostic effect extended temozolamide on survival outcomes of glioblastoma multiforme patients who were underwent surgery/biopsy followed treated with definitive chemo-radiotherapy. Materials and Methods: We retrospectively analyzed the datas of 225 patients with gliablastoma multiforme whom admitted to our clinic All patients were completed concomitant chemoradiotherapy with temozolamide and adjuvant temozolamide therapy at least for six months or more. Patients were divided into two groups as standart and extended temozolamid therapy group as using temozolamide therapy for at least 6 months or more. Results: The median follow-up of the whole patients18 (range 2-125) months, 65 patients (56%) were alive. Extended temozolamide (>6) was associated with longer survival, but was not significantly with survival outcomes in the univariate analysis (49.0 vs 68.33 months; p=0.082). However, progression free survival analysis demonstrated that the patient in extended temozolamide group had paramount extended progression free survival (14 vs 9 months) than other group in standart cycle temozolamide. Conclusion: Our study show that extended temozolamide is good tolerated and leads to a significantly increase in progression free survival and overall survival in newly diagnosed patients with glioblastoma multiforme.
The effect of androgen deprivation therapy on 68GA-PSMA-tracer uptake in nonmetastatic prostate cancer patients
(2020) Cem, Onal; Guler, Ozan Cem; Torun, Nese; Reyhan, Mehmet; Yapar, Ali Fuat; 0000-0002-5597-676X; 0000-0003-1715-4180; 0000-0001-8550-3368; 0000-0001-6908-3412; AAE-2718-2021; AAI-8973-2021; AAJ-5242-2021; AAC-5654-2020
The effect of androgen deprivation therapy on Ga-68-PSMA tracer uptake in non-metastatic prostate cancer patients
(2020) Onal, Cem; Guler, Ozan Cem; Torun, Nese; Reyhan, Mehmet; Yapar, Ali Fuat; 0000-0002-5597-676X; 0000-0001-8550-3368; 0000-0003-1715-4180; 0000-0001-6908-3412; 0000-0002-2742-9021; 31732768; AAE-2718-2021; AAJ-5242-2021; AAI-8973-2021; AAC-5654-2020; D-5195-2014
Purpose To evaluate the effect of neoadjuvant androgen deprivation treatment (ADT) on prostate-specific membrane antigen (PSMA) tracer uptake demonstrated in Ga-68-PSMA-positron emission tomography (PET/CT) in non-metastatic hormone-naive prostate cancer (PC) patients. Materials and methods The clinical data of 108 PC patients who received neoadjuvant ADT were retrospectively analyzed. All patients had a baseline Ga-68-PSMA-PET/CT scan, and a second scan was delivered median of 2.9 months after the initiation of ADT. The maximum standardized uptake value (SUVmax) of primary tumor (SUVp) and metastatic lymph nodes (SUVln) as well as PSA response were assessed between pre- and post-ADT Ga-68-PSMA-PET/CT scans. Results There were significant decreases in posttreatment serum PSA, SUVp, and SUVln. A decrease in SUVp was seen in 91 patients (84%) with a median value of 66% (range, 5-100%), while 17 patients (16%) had no change in or an increase in PSMA tracer uptake with a median value of 24% (range, 0-198%). Patients with Gleason score (GS) of 7 had significantly higher metabolic response rates compared to other patients. The disease progression was significantly higher only in patients with GS > 7 disease compared to GS 7 disease. The PSA response to ADT was the lowest in patients with ISUP high-grade tumors. A total of 16 patients (15%) had progressive disease, and in 9 patients (8%), radiotherapy decisions were modified according to posttreatment Ga-68-PSMA-PET/CT scans. Conclusions The current study includes the largest number of patients analyzed to date and demonstrates that ADT causes a significant decrease in serum PSA values and SUVp and SUVln. The authors demonstrate that Ga-68-PSMA-PET/CT may be used as a quantitative imaging modality after neoadjuvant ADT in hormone-naive non-metastatic PC patients.
Estimation of secondary cancer risk after radiotherapy in high-risk prostate cancer patients with pelvic irradiation
(2020) Haciislamoglu, Emel; Gungor, Gorkem; Aydin, Gokhan; Canyilmaz, Emine; Guler, Ozan Cem; Zengin, Ahmet Yasar; Yenice, Kamil Mehmet; 0000-0001-6908-3412; 32671989; AAC-5654-2020
We aimed to estimate the risk of secondary cancer after radiotherapy (RT) in high-risk prostate cancer (HRPC) patients with pelvic irradiation. Computed tomography data of five biopsy-proven HRPC patients were selected for this study. Two different planning target volumes (PTV(1)and PTV2) were contoured for each patient. The PTV(1)included the prostate, seminal vesicles, and pelvic lymphatics, while the PTV(2)included only the prostate and seminal vesicles. The prescribed dose was 54 Gy for the PTV(1)with a sequential boost (24 Gy for the PTV2). Intensity-modulated RT (IMRT) and volumetric modulated arc therapy (VMAT) techniques were used to generate treatment plans with 6 and 10 MV photon energies with the flattening filter (FF) or flattening filter-free (FFF) irradiation mode. The excess absolute risks (EARs) were calculated and compared for the bladder, rectum, pelvic bone, and soft tissue based on the linear-exponential, plateau, full mechanistic, and specific mechanistic sarcoma dose-response model. According to the models, all treatment plans resulted in similar risks of secondary bladder or rectal cancer and pelvic bone or soft tissue sarcoma except for the estimated risk of the bladder according to the full mechanistic model using IMRT((6MV;FF))technique compared with VMAT techniques with FFF options. The overall estimation of EAR indicated that the radiation-induced cancer risk due to RT in HRPC was lower for bladder than the rectum. EAR values ranged from 1.47 to 5.82 for bladder and 6.36 to 7.94 for rectum, depending on the dose-response models used. The absolute risks of the secondary pelvic bone and soft tissue sarcoma were small for the plans examined. We theoretically predicted the radiation-induced secondary cancer risk in HRPC patients with pelvic irradiation. Nevertheless, prospective clinical trials, with larger patient cohorts with a long-term follow-up, are needed to validate these model predictions.
Graves' Ophthalmopathy Treated with Protracted Hypofractionated Low-Dose Adaptive Radiotherapy: Case Report and Review of The Literature
(2016) Guler, Ozan Cem; Onal, Cem; https://orcid.org/0000-0001-6908-3412; https://orcid.org/0000-0002-2742-9021; 26466836; AAC-5654-2020; HOC-5611-2023
Graves' ophthalmopathy (GO) is the most common extra-thyroidal manifestation of Graves' disease. The treatment options for GO are high-dose glucocorticoids, selenium, rituximab, cyclosporine, orbital radiotherapy (RT), and surgery. A 43-year-old male patient was referred to our clinic with complaints of severe bilateral proptosis, diplopia, and orbital pain at both globes for 1 year. Pretreatment magnetic resonance imaging revealed bilateral proptosis, the expansion of bilateral optic nerves sheath, the increase of right medial muscle thickness, and a mass at the right eyehole. Patient was treated with 1 Gy per fraction per week with a total dose of 10 Gy over 10 weeks with adoptive intensity-modulated radiotherapy technique. During RT at 3rd and 6th weeks, a moderate shrinkage of the lesions was observed. The patient has been disease free, has had no complaints for 36 months, and has not required any surgical intervention. No late side effects such as retinopathy or cataract were observed. Orbital RT with innovative techniques may be considered as an initial local treatment for GO. With adoptive protracted low dose RT, a good clinical and radiological response could be seen without increasing early and late reactions.
Half-dose bevacizumab experience in relapsed ovarian cancer patients in Turkey due to formal regulations: similar effectiveness with lower rate of hypertension
(2020) Kose, Fatih; Alemdaroglu, Songul; Mertsoylu, Huseyin; Besen, Ali Ayberk; Guler, Ozan Cem; Simsek, Seda Yuksel; Erbay, Gurcan; Onal, Cem; Celik, Husnu; 0000-0003-4335-6659; 0000-0002-2742-9021; 0000-0001-6908-3412; 0000-0002-1706-8680; 0000-0002-0156-5973; 0000-0002-7862-0192; 0000-0002-1932-9784; 33099934; AAI-8400-2021; D-5195-2014; AAC-5654-2020; AAK-5370-2021; G-4827-2016; AAK-7016-2021; AAD-6910-2021; M-9530-2014
Purpose: Ovarian cancer is the fifth leading cause of cancer related death in women. Platin-based doublet regimens plus bevacizumab is standard treatment in relapse. Due to formal regulation of Turkish Ministry of Health, adjuvant bevacizumab has not been reimbursed and clinicians can use bevacizumab at a dose of 7.5 mg/kg/3wk in platin-resistant and sensitive relapse settings. The primary aim of this study was to evaluate 7.5 mg/kg/3wk bevacizumab dosing in platin-resistant and sensitive relapse ovarian cancer and compare these findings with the current literature. Methods: A total of 106 patients with relapsed ovarian cancer and treated with bevacizumab (bevacizumab is not reimbursed as a part of adjuvant treatment in Turkey) on their first relapse were included. Results: At a median follow-up of 32.1 months (5.3-110.8), 56 (52.8%) patients died. Progression-free survival (PFS) and overall survival (OS) were estimated at 18.8 months (14.4-23.3) vs 29.7 months (24.3-35.1) of the whole group overall survival. We observed that 78.4% of patients treated with primary surgery without neoadjuvant treatment and 59 (57.8%) out of the 102 patients with debulking surgery relapsed. A significant number of patients (81%) treated with primary surgery without neoadjuvant treatment and 59 (76.6 %) had secondary debulking surgery at relapse. In relapse, 38 patients were treated with single agent liposomal doxorubicin (LPD) plus bevacizumab. On the other hand, 68 patients were treated with carboplatin and LPD plus bevacizumab. Multivariate analysis failed to show any clinicopathological characteristics with significant effect on PFS. However, cytoreductive surgery at relapse showed significant effect on OS. Bevacizumab-related toxicities were detected in 23 (21.7%) patients; hypertension, pulmonary embolism, perforation, and other toxicities (nephrotic syndrome in 2, osteonecrosis in 2, cerebrovascular and cardiac ischemia in 3 patients) were seen in 12 (11.3%), 3 (2.8%), 1 (0.9%) and 7 (6.6%) patients, respectively. Conclusions: In conclusion, our findings showed that 7.5 mg/ kg/3week dosing of bevacizumab in relapsed ovarian cancer could have similar effectiveness compared to standard 15 mg/ kg/3week dosing. Increase of OS and PFS in patients treated with primary and secondary debulking surgery with no-visible disease was more pronounced. No new safety information was observed but lower rate of grade 3 or above hypertension with similar rate of severe vascular and intestinal complications were detected.
The hematologic parameters in metastatic castration-resistant prostate cancer patients treated with abiraterone acetate
(2019) Onal, Cem; Sedef, Ali Murat; Kose, Fatih; Oymak, Ezgi; Guler, Ozan Cem; Sumbul, Ahmet Taner; Aksoy, Sercan; Yildirim, Berna Akkus; Besen, Ali Ayberk; Muallaoglu, Sadik; Mertsoylu, Huseyin; Ozyigit, Gokhan; 0000-0001-6908-3412; 0000-0002-5573-906X; 0000-0002-0156-5973; 30977383; D-4793-2014; AAC-5654-2020
Currently, there are no predictive markers of response to abiraterone. We calculated neutrophil-to-lymphocyte ratio (NLR) and platelet-to-lymphocyte ratio (PLR) at baseline and at 4 and 12 weeks after initiation of abiraterone, and we evaluated prostate-specific antigen (PSA) response every 4 weeks in 102 metastatic castration-resistant prostate cancer (mCRPC) patients treated with abiraterone either pre-or postchemotherapy. With a median follow-up was 24.0 months (range: 0.3-54.9), median overall survival (OS) was 20.8 months. High-NLR patients who remained high or who returned to low NLR after 4 and 12 weeks showed significantly worse OS than patients with low baseline NLR. NLR and prostate-specific antigen response to abiraterone was a significant predictor of OS and progression-free survival (PFS) in metastatic castration-resistant prostate cancer patients treated with abiraterone delivered either pre-or postchemotherapy.
The hematologic parameters in metastatic castration-resistant prostate cancer patients treated with abiraterone acetate.
(2019) Cem, Onal; Sedef, Ali Murat; Kose, Fatih; Oymak, Ezgi; Guler, Ozan Cem; Sumbul, Ahmet Taner; Aksoy, Sercan; Yildirim, Berna Akkus; Besen, Ali Ayberk; Mullaoglu, Sadik; Mertsoylu, Huseyin; Ozyigit, Gokhan; 0000-0001-6908-3412; D-4793-2014; AAC-5654-2020
Impact of lymph node ratio in patients with stage IIIC endometrial carcinoma treated with postoperative radiotherapy
(2021) Onal, Cem; Sari, Sezin Yuce; Yavas, Guler; Guler, Ozan Cem; Yiğit, Ecem; Oymak, Ezgi; Gultekin, Melis; Yildiz, Ferah; 0000-0002-2742-9021; 34355983; D-5195-2014
Aim: To evaluate the prognostic value of the lymph node ratio (LNR) and other clinicopathological factors in patients with stage IIIC endometrial cancer. Methods: Factors affecting overall survival (OS) and progression-free survival (PFS) were assessed in 397 patients with stage IIIC endometrial cancer treated with postoperative radiotherapy. Patients undergoing the removal of at least ten lymph nodes were included in the study. Results: The 5-year OS and PFS rates were 58% and 52%, respectively, with a median follow-up time of 35.7 months. The LNR cutoff value was 9.6%. In the multivariate analysis, advanced age (>= 60 years), grade III tumor, presence of cervical stromal invasion, higher LNR and lack of adjuvant chemotherapy were independent predictors for worse OS and PFS. Conclusion: The LNR is an independent predictor for OS and PFS in patients with stage IIIC endometrial cancer treated with postoperative radiotherapy.