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Öğe Acute effect of palonosetron on electrocardiographic parameters in cancer patients: a prospective study(SPRINGER, 2012) Yavas, C.; Dogan, U.; Yavas, G.; Araz, M.; Ata, O. YavasPalonosetron is a novel 5-hydroxytryptamine(3) (5 HT3) receptor antagonist, which has been shown to be superior to first generation 5 HT3 receptor antagonists regarding the prevention of acute, delayed and overall chemotherapy-induced nausea and vomiting. First generation 5 HT3 receptor antagonists may induce electrocardiographic changes of heart rate and repolarization. The acute cardiac effect of palonosteron is unknown. The purpose of this study is to determine acute effects of palonosetron on electrocardiographic (ECG) parameters in cancer patients. The study had a prospective design. Seventy-six cancer patients with normal cardiac function who received palonosetron for prevention of chemotherapy-induced nausea and vomiting were enrolled. Standard 12-lead ECG recordings were performed at baseline and 30 min after palonosetron administration. P wave durations and corrected QT intervals were measured; P wave dispersion (Pd) and QTc dispersion were calculated. Median heart rate did not differ among 76 patients enrolled before and after palonosetron administration (p: 0.6). Systolic and diastolic blood pressures were not significantly different before and after palonosteron (p values 0.9 and 0.3, respectively). Although median QT min value was higher after palonosetron administration than before palonosetron administration, the difference was not statistically significant (p: 0.6). Palonosetron seems to have no acute arrhythmogenic potential.Öğe Adjuvant Carboplatin and Paclitaxel after Concurrent Cisplatin and Radiation Therapy in Patients with Locally Advanced Cervical Cancer(ELSEVIER SCIENCE INC, 2018) Yavas, G.; Yavas, C.; Sen, E.; Oner, I.; Celik, C.; Ata, O.[Abstract not Available]Öğe Amelioration of Radiation-Induced Intestinal Toxicity by Beta-Hydroxy-Beta-Methyl-Butyrate, L-Glutamine, and L-Arginie: Results of an Experimental Study(ELSEVIER SCIENCE INC, 2016) Yavas, C.; Yavas, G.; Celik, E.; Buyukyoruk, A.; Buyukyoruk, C.; Yuce, D.; Ata, O.[Abstract not Available]Öğe Amelioration of radiation-induced lung injury by halofuginone: An experimental study in Wistar-Albino rats(SAGE PUBLICATIONS LTD, 2017) Calik, M.; Yavas, G.; Calik, S. G.; Yavas, C.; Celik, Z. E.; Sargon, M. F.; Esme, H.To evaluate effects of halofuginone (H) on radiation-induced lung injury (RILI), 60 rats were divided into six groups: Group (G) 1 control, G2 radiotherapy (RT) only, G3 and G4 2. 5 and 5 g H and G5 and G6 RT + 2.5 and 5 g H groups, respectively. A single dose of 12 Gy RT was given to both lungs. H was applied intraperitoneally with daily doses, until animals were killed at 6 and 16 weeks after RT. At 6th and 16th weeks of RT, five rats from each group were killed. Lung tissues were dissected for light and electron microscopy. Chronic inflammation, fibrosis and transforming growth factor-beta (TGF)- scores of all study groups were significantly different at 6th and 16th week (p < 0.001). Chronic inflammation, fibrosis and TGF- scores of G2 were higher than G5 and G6 at 6th and 16th weeks of RT. At 16th week, fibrosis and TGF- scores of G5 were higher than G6 (p = 0.040 and 0.028, respectively). Electron microscopical findings also supported these results. Therefore, H may ameliorate RILI. The effect of the H was more prominent at higher dose and after long-term follow-up. These findings should be clarified with further studies.Öğe Correliation Between Osteopontin Protein Expression and Histological Grade of Astrocytomas(SPRINGER, 2009) Toy, H.; Yavas, O.; Eren, O.; Genc, M.; Yavas, C.Osteopontin is a ligand for the integrin proteins, which are cell surface receptors that mediate the physical and functional interactions between a cell and the extracellular matrix. The expression of osteopontin is reportedly increased in a number of transformed cell lines and tumor tissues. Furthermore, increased expression of osteopontin results in some infiltrative features of tumors. The aim of the study is to demonstrate that expression of osteopontin in human astrocytomas correlates with histological tumor grade. The expression of osteopontin in human astrocytomas was determined with immunohistochemistry. Median osteopontin expression levels were 1%, 7.5%, 60%, and 50% in grade I, II, III, and IV tumors, respectively. Osteopontin staining was significantly higher in high grade (grade III-IV) than low grade (grade I-II) tumors. These findings indicate that osteopontin immunoreactivity in human astrocytomas may correlate with the grade of a tumor.Öğe Dosimetric comparison of two different whole brain radiotherapy techniques in patients with brain metastases: How to decrease lens dose?(IJRR-IRANIAN JOURNAL RADIATION RES, 2014) Yavas, G.; Yavas, C.; Gul, O. V.; Acar, H.; Ata, O.Background: Palliative whole brain radiotherapy (WBRT) has been the standard treatment for brain metastases. Ionizing radiation is known to be one of the most potent cataractogenic agents. We aimed to evaluate two different radiotherapy techniques with respect to the doses received by the organs at risk (OAR) in patients with brain metastasis who undergone WBRT. Materials and Methods: Ten consecutive patients with brain metastasis were included. For each patient, two different treatment plans were created for whole brain. Helmet-field (HF) (anterior border was 2 cm posterior to lens, inferior border was the bottom of C2 vertebra) and classical technique with collimation (CT) (anterior border was defined as skin fall off, inferior border was the bottom of cranial base) were generated for all patients. Two techniques were compared with respect to the doses received by the OAR including bilateral lenses, optic nerves and eye-balls, the dose homogeneity index (DHI), and the monitor unit counts (MU) required for the treatment. Student-t test was used for statistical analysis. Results: There was no difference between two techniques in terms of both DHI (p: 0.182) and MU counts (p: 0.167). The maximum and mean doses received by the right lens, left lens and right eye-ball were significantly reduced with CT (p values for maximum doses 0.007, 0.012 and 0.010; for median doses 0.027, 0.046 and 0.002 respectively). Conclusion: CT was found to be more advantageous, with respect to the lens doses in addition the dose received by the right eye-ball during WBRT.Öğe Dosimetric comparison of whole breast radiotherapy using field in field and conformal radiotherapy techniques in early stage breast cancer(IJRR-IRANIAN JOURNAL RADIATION RES, 2012) Yavas, G.; Yavas, C.; Acar, H.Background: We aimed to compare field-in-field technique (FIF) with conformal tangential field radiotherapy (CRT) in terms of dosimetric benefits for early stage breast cancer radiotherapy. Materials and Methods: Twenty consecutive left-side breast cancer patients who underwent breast-conserving surgery were included to the study. For each patient, two different treatment plans were created for the entire breast. FIF plans and CRT plans were compared for doses in the planning target volume (PTV), the organ at risk (OAR) volume including ipsilateral lung, heart, left ascending coronary artery (LAD) and the contralateral breast, the homogeneity index (HI), and the monitor unit (MU) counts required for the treatment. Paired samples t-test was used for statistical analysis. Results: The FIF technique significantly reduced the maximum dose of the PTV as well as the mean doses of the heart, LAD, ipsilateral lung and the contralateral breast (p values were <0.001 for each). When the OAR volumes irradiated with 2, 5, 10, 20, 30 and 40 Gy were compared, the results were in favor of the FT technique. The volume receiving <20 Gy of the prescription dose for the ipsilateral lung was significantly decreased using FIF technique (p<0.001). FIF technique allowed us more homogenous dose distribution with lower MUs. Conclusion: The FIF technique provided better dose distribution in the PTV and significantly reduced the doses in the OAR. Considering the lower MUs required for treatment the FIF technique seems to be more advantageous than CRT during whole breast irradiation. Iran. J. Radiat. Res., 2012; 10(3-4): 131-138Öğe Effect of radiation on cytokines, MMP-1 and type I collagen mRNA expressions in human gingival fibroblasts.(AMER SOC CLINICAL ONCOLOGY, 2011) Yavas, G.; Yavas, C.; Bozkurt, B.; Ata, O.; Hakki, S.[Abstract not Available]Öğe Evaluation of doses in the Wernicke and Broca's areas using two different technique in patients with right frontal glioblastoma multiforme(IJRR-IRANIAN JOURNAL RADIATION RES, 2013) Acar, H.; Yavas, G.; Yavas, C.Background: Broca's and Wernicke's areas, which are important language areas of brain, are commonly irradiated in patients with right frontal lobe glioblastomamultiforme (GBM). We aimed to compare two different treatment planning techniques in terms of the doses in the Broca's and Wernicke's areas for the patients with right frontal GBM. Materials and Methods: Two different treatment planning techniques of right frontal GBM were generated for Rando phantom: two field technique using parallel opposed beams and three field techniques. Both plans were compared for doses in planning target volume (PTV), Broca's and Wernicke's areas. Additionally to test the accuracy of treatment planning system (TPS) dose calculation; thermoluminescent dosimeters (TLD) were used. Results: The three field technique allowed the lower doses in the Broca's and Wernickes's areas. The doses calculated in the Broca'sand Wernicke's areas were 0.98% +/- 0.03 and 0.09% +/- 0.06 of the isocenter dose with three field and 1.06% +/- 0.04 and 0.133% +/- 0.03 of the isocenter dose with two field techniques respectively. When the doses measured by TLD and calculated with TPS were compared; the differences were 3.23% and 2.92 % for Broca's area, and 4.12 % and 3.95% for Wernicke's area for two field and three field techniques respectively. Conclusion: There was a good agreement between TPS and TLD calculations for both techniques. Three field techniques seem to be more advantageous than two field technique with respect to doses of Broca's and Wernicke's areas. However this finding should be clarified with further clinical studies.Öğe Evaluation of the acute effect of palonosetron on transmural dispersion of myocardial repolarization(VERDUCI PUBLISHER, 2012) Dogan, U.; Yavas, G.; Tekinalp, M.; Yavas, C.; Ata, O. Y.; Ozdemir, K.Background: 5-hydroxytryptamine receptor type-3 (5-HT3) antagonists are widely used for prophylaxis of chemotherapy-induced nausea and vomiting (CINV) and regarded to have a high safety profile. However, several electrocardiographic changes and cardiac arrhythmias have been reported due to administration of 5-HT3 antagonists. Only prolongation of QT interval has been investigated as an index of potential for life-threatening arrhythmias in adult patients using 5-HT3 antagonists. Recently, increase in transmural dispersion of repolarization (TDR) has been proposed as a more reliable determinant of arrhythmogenic potential. Aim: To assess the effects of palonosetron, a second-generation 5-HT3 antagonist, on the T-wave peak to T-wave end (TpTe) interval which has been proposed as a reliable index of spatial TDR. Patients and Methods: A total of 50 consecutive cancer patients (aged: 57 +/- 12 years) who were scheduled to receive emetogenic chemotherapy were included to the study. Baseline12-lead electrocardiography (ECG) recordings were obtained. Then, all patients received 8 mg intravenous dexamethasone followed by a single dose of 0.25 mg intravenous palonosetron administered over 30 seconds. A second ECG was performed 30 minutes after the administration of palonosetron. Indices of cardiac repolarization and TOR before and after the administration of palonosetron were compared. Results: In comparison with baseline there was no statistically significant change in any of the heart rate-corrected parameters, including QT(c) (lead V-5), QT(maxc), QT(minc), QT(cd), TpTe (V-5), TpTe(max), TpTe(min), TpTe(d) and TpTe/QT (V-5). Conclusions: Palonosetron does not have any significant effect on QT(c) and TpTe intervals. It might be the drug of choice for prophylaxis of CINV in cancer patients receiving chemotherapy with known cardiotoxic potential or who have pre-existing cardiac disease that predispose them to drug-induced arrhythmias.Öğe Imiquimod Attenuates Radiation-Induced Pulmonary Fibrosis(ELSEVIER SCIENCE INC, 2018) Calik, M.; Yavas, G.; Celik, E.; Yavas, C.; Calik, G.; Sargon, M.; Sanli, Y.[Abstract not Available]Öğe The impact of dose calculation algorithms for peripheral dose distributions of enhanced dynamic and physical wedges(IJRR-IRANIAN JOURNAL RADIATION RES, 2016) Acar, H.; Yavas, G.; Yavas, C.Background: In radiation therapy, the peripheral dose is important when anatomical structures with very low dose tolerances are involved. In this study, the two available calculation algorithms of the Varian Eclipse 8.6 treatment planning system(TPS), the anisotropic analytic algorithm (AAA) and pencil-beam convolution (PBC) was used to compare measured and calculated peripheral dose distribution of physical wedged (PW) and enhanced dynamic wedged fields (EDW). Materials and Methods: Peripheral dose measurements were carried out for 6 and 18 MV photons using a 0.6cc Farmer-type ionization chamber in the slab phantom. Measurements were performed using 15 degrees, 30 degrees, 45 degrees and 60 degrees PW and EDW for three different field sizes at d(max) and up to a maximum distance of 50 cm beyond the field edges. peripheral dose was further computed using two different algorithms of a TPS. The measured and calculated datas were then compared to find which algorithm calculates peripheral dose distribution more accurately. Results: Both algorithms from the TPS adequately model the peripheral dose distribution up to 45 degrees. For large field sizes with 60 degrees EDW, the largest deviation between calculated and measured dose distribution is less than 3.5% using the AAA, but can increase up to 9.7% of the distribution using PBC. Conclusion: The AAA models wedged peripheral dose distributions more accurately than the PBC does for all studied conditions; the difference between the algorithms are more significant for large wedge angles and large field sizes. It must be emphasized that the use of PBC for planning large-field treatments with 60 degrees EDW could lead to inaccuracies of clinical significance.Öğe The Impact of Spironolactone on the Lung Injury Induced by Concomitant Trastuzumab and Thoracic Radiotherapy -- 2(ELSEVIER SCIENCE INC, 2018) Yavas, G.; Yavas, C.; Celik, E.; Sen, E.; Ata, O.; Yuce, D.; Elsurer-Afsar, R.[Abstract not Available]Öğe A novel case of quartet tumor: meningioma, angiomyolipoma, ependymoma and sarcoma: report of a case and review of the literature(IJRR-IRANIAN JOURNAL RADIATION RES, 2015) Yavas, C.; Karabagli, P.; Yavas, G.; Acar, H.; Ata, O.Multiple primary tumors in a single patient are relatively rare when four or more distinct lesions are considered. Herein, we report a case of woman with four different primary tumors: meningioma, renal angiomyolipoma, spinal ependymoma and high-grade soft tissue sarcoma. There was no family history and hereditary syndrome. The genetic analysis was completely normal. To best of our knowledge, the present patient is the first case in the literature, who presented with these four types of tumors.Öğe Pancreatic adenocarcinoma in a patient with relapsed Hodgkin's lymphoma(IJRR-IRANIAN JOURNAL RADIATION RES, 2013) Yavas, G.; Araz, M.; Yavas, C.; Baba, F.; Ata, O.After curative treatment of Hodgkin's lymphoma, increased risk of certain solid tumors has been reported. To best of our knowledge this is the first report of metachronous pancreatic adenocarcinoma which developed outside the previous radiation field in a patient with relapse Hodgkin's lymphoma. Herein we present an 81-year-old female who developed pancreatic adenocarcinoma four years after the curative treatment of Hodgkin's lymphoma.Öğe RADIOTHERAPY IN GYNECOLOGICAL CANCERS: ANALYSIS OF TREATMENT RESULTS AND PROGNOSTIC FACTORS(LIPPINCOTT WILLIAMS & WILKINS, 2013) Yavas, G.; Dogan, N. U.; Yavas, C.; Tazegul, A.; Celik, C.[Abstract not Available]Öğe The use of concurrent hormonotherapy and radiotherapy does not deteriorate radiation-induced cardiac toxicity(SAGE PUBLICATIONS LTD, 2017) Yavas, C.; Yavas, G.; Toy, H.; Ata, O.Postmenopausal patients with breast cancer have two options for adjuvant endocrine therapy, tamoxifen and aromatase inhibitors (AIs) as well as radiotherapy (RT) and chemotherapy. However, there is limited data regarding the optimal sequencing of RT and tamoxifen/AIs. Thus, we aimed to evaluate the effects of tamoxifen and AIs on radiation-induced cardiotoxicity. Eighty ovariectomized rats were divided into eight groups (G). G1 was defined as a control group; G2, G3, G4, and G5 were RT, tamoxifen, anastrozle, and letrozole groups, respectively; G6, G7, and G8 were RT plus tamoxifen, anastrozle, and letrozole groups, respectively. Drugs were started 1 week before RT and continued until the animals were killed 16 weeks after RT. The heart tissues were then dissected and examined with light microscopy to determine endocardial thickness and cardiac fibrosis. The endocardial thickness scores of both RT alone and the tamoxifen groups as well as the cardiac fibrosis score of RT alone were higher than that the control group (p < 0.05 for all). There was no difference in the endocardial thickness and cardiac fibrosis scores of the RT-only group and the RT plus hormonotherapy groups (p > 0.05 for all). Concurrent administration of RT and hormonal therapy with either tamoxifen or AIs did not further amplify radiation-induced cardiac toxicity. This issue warrants further study.
