Ahmet Karadeniz
Istanbul University
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Publication
Featured researches published by Ahmet Karadeniz.
American Journal of Clinical Oncology | 2000
Adnan Aydiner; Ahmet Karadeniz; Kazim Uygun; Siirsel Tas; Faruk Tas; Rian Disci; Erkan Topuz
During the 10-year period (1987-1996) of our study, 26,255 patients with cancer were admitted to our clinic and, of these, 271 (1%) patients had multiple primary malignant tumors. Ninety-two (34%) patients had synchronous tumors (synchronous group), and 179 (66%) patients had metachronous tumors (metachronous group). The mean age at first diagnosis was higher in the former group. The ratio of men to women was 1.36 in the synchronous group and 0.74 in the metachronous group (p = 0.018). Smokers and drinkers were more common in the synchronous group. Breast cancer and lung cancer were most prevalent, and associations between head/neck and lung cancer and between breast and breast cancer were the most frequent associations in both the synchronous and the metachronous group. The frequency of aerodigestive tumors was higher and that of mesenchymal tumors was lower in the synchronous group than in the metachronous group. Localization in the medial region and in the head/neck was more frequent in the synchronous group than in the case of metachronous secondary tumors.
Journal of Cranio-maxillofacial Surgery | 2009
Merdan Fayda; Gorkem Aksu; Fulya Yaman Agaoglu; Ahmet Karadeniz; Emin Darendeliler; Musa Altun; Gunter Hafiz
BACKGROUND Thirty adult patients with head and neck soft tissue sarcoma (HNSTS) treated between 1987 and 2000 were retrospectively analysed. PATIENTS AND METHODS The most frequent histopathological subtypes were chondrosarcomas (27%) and malignant fibrous histiocytoma (20%). The surgical resection was performed in 25 of the 30 patients (83%). Twenty-three patients in the surgical resection arm received postoperative radiotherapy. RESULTS Five-year local control rates for patients with negative surgical margins (n=9), microscopically positive disease (n=10), gross residual disease (n=6) and inoperable cases (n=5) were 64, 70, 20 and 0%, respectively. However, there was no significant difference in local control between patients with negative or microscopically positive disease who received postoperative radiotherapy (71 vs. 70%). The patients who received doses>or=60 Gy had significantly higher local control rates than the ones who received doses lower than 60 Gy (p=0.048). The local control rates were lower in patients with grade 2-3 tumours when compared with grade 1 tumours (44 vs. 83%). The median overall survival of whole group was 31 months. Median survivals of patients receiving both surgery and radiotherapy with negative and microscopically positive margins were significantly better than patients who were not treated with surgery (34.8 and 36 vs. 13.3 months). CONCLUSION Our results confirm that the optimal treatment of HNSTSs is complete surgical excision, and that postoperative adjuvant radiotherapy clearly improves local control.
Brain Research | 2004
Mehmet Kaya; Ayse Palanduz; Rivaze Kalayci; Gönül Kemikler; Gonul Simsek; Bilge Bilgic; Bulent Ahishali; Nadir Arican; Zuhal Celebi Kocyildiz; Imdat Elmas; Mutlu Kucuk; Ahmet Karadeniz
The use of radiation to improve the efficacy of chemotherapy on malignant brain tumors is also known to cause side effects on vascular endothelial cells and astrocytes in normal parts of the brain. We investigated the effects of lipopolysaccharide (LPS) on the functional and structural properties of blood-brain barrier (BBB) and the activity of astrocytes during whole-brain irradiation in rats. The permeability of the BBB to Evans blue (EB) dye significantly increased in the cerebral cortex, diencephalon and cerebellum regions of rats exposed to irradiation (P<0.01). In contrast, the BBB permeability in irradiated rats was significantly reduced by LPS (P<0.05). Tumor necrosis factor-alpha (TNF-alpha) levels were increased following LPS, irradiation and irradiation plus LPS (P<0.05, P<0.01). Irradiated brain vessels showed a considerable loss of staining intensity of tight junction proteins Zonula occludens-1 (ZO-1) and occludin. Staining for Zonula occludens-1 and occludin was intensive in animals treated with LPS and irradiation plus LPS. Glial fibrillary acidic protein (GFAP) immunoreactivity was seen in very few astrocytes of irradiated brains. However, this staining showed an increased positive intensity in the brain sections of LPS-treated as well as of irradiation plus LPS-treated animals. These results indicate that LPS reduces the passage of exogenous vascular tracer EB-binding albumin into the brain, at least partly, by increasing the expression of tight junction proteins and GFAP, following the irradiation. We suggest that irradiation may affect paracellular permeability through disruption of tight junction proteins, Zonula occludens-1 and occludin, and LPS could provide beneficial effects on the BBB integrity and the astrocytes against irradiation damage.
Brain Research | 2009
Candan Gürses; Oguzhan Ekizoglu; Nurcan Orhan; Duran Ustek; Nadir Arican; Bulent Ahishali; Imdat Elmas; Mutlu Kucuk; Bilge Bilgic; Gönül Kemikler; Rivaze Kalayci; Ahmet Karadeniz; Mehmet Kaya
This study investigates the effects of levetiracetam (LEV) on the functional and structural properties of blood-brain barrier (BBB) in pentylenetetrazole (PTZ)-kindled rats with cortical dysplasia (CD). Pregnant rats were exposed to 145 cGy of gamma-irradiation on embryonic day 17. In offsprings, kindling was induced by giving subconvulsive doses of PTZ three times per week for 45 days. While all kindled rats with CD died during epileptic seizures evoked by the administration of a convulsive dose of PTZ in 15 to 25 min, one week LEV (80 mg/kg) pretreatment decreased the mortality to 38% in the same setting. LEV caused a remarkable decrease (p<0.01) in extravasation of sodium fluorescein dye into the brain tissue of kindled animals with CD treated with convulsive dose of PTZ. Occludin immunoreactivity and expression remained essentially unchanged in all groups. Immunoreactivity for glial fibrillary acidic protein (GFAP) was observed to be slightly increased by acute convulsive challenge in kindled rats with CD while LEV pretreatment led to GFAP immunoreactivity comparable to that of controls. An increased c-fos immunoreactivity in kindled rats with CD exposed to convulsive PTZ challenge was also observed with LEV pretreatment. Tight junctions were ultrastructurally intact, whereas LEV decreased the increased pinocytotic activity in brain endothelium of kindled rats with CD treated with convulsive dose of PTZ. The present study showed that LEV decreased the increased BBB permeability considerably by diminishing vesicular transport in epileptic seizures induced by convulsive PTZ challenge in kindled animals with CD.
Oncology | 2011
Faruk Tas; Serkan Keskin; Ahmet Karadeniz; Nergiz Dagoglu; Fatma Sen; Leyla Kilic; Ibrahim Yildiz
Objective: Compared to the cutaneous melanoma, noncutaneous melanomas are relatively rare and have a distinct pattern of behavior. We performed this study to define the clinical characteristics and outcomes of patients with noncutaneous melanomas and emphasize how they differ from cutaneous melanomas. Methods: 216 patients who were diagnosed with noncutaneous melanoma were assessed and their medical records between 2000 and 2010 were retrieved from the cancer registry. 475 patients with cutaneous melanoma were used for comparison. Results: Of the 216 noncutaneous melanoma patients, 83 had mucosal melanoma, 101 had ocular melanoma and 32 had unknown primaries. For mucosal melanoma, the head and neck was the most common anatomic site (53%), followed by the gastrointestinal tract (37%), female genital (6%) and urinary tract (4%). The majority of the ocular melanomas (94%) originated in the uvea. 32 patients demonstrated a primary unknown disease with regional metastasis as the dominant behavior (72%). Age was found to be statistically significantly different among melanoma patients (p < 0.001). Younger patients had more cutaneous and unknown primary melanomas, whereas older patients had more ocular and mucosal melanoma. In subset analyses, we found significant differences between cutaneous and ocular (p = 0.038) or mucosal (p < 0.001) melanomas. The ratios of metastasis on admission were higher in patients with mucosal (27.7%) and unknown primary (28.1%) melanomas, and lower for ocular (3%) melanomas (p < 0.001). Patients with cutaneous melanoma had an intermediate (12%) ratio. Patients with ocular melanoma had better outcome than patients with other melanoma sites (p < 0.05). While overall survival for cutaneous melanoma was significantly negatively correlated with male gender (p < 0.001), advanced stages (p < 0.001) and old age (p = 0.005), stage IV disease was the only independent prognostic factor in patients with ocular melanoma (p = 0.006). No prognostic factor for outcome was found for either mucosal or unknown primary melanomas. Conclusion: The clinical presentations and prognoses of different primary sites of melanoma are distinctive. Therefore, approaches to these melanomas should be different.
Orthopedics | 2008
Gorkem Aksu; Merdan Fayda; Mert Saynak; Ahmet Karadeniz
This article presents a case of multiple vertebral hemangiomas in a 58-year-old man with pain in the dorsal region and bilateral progressive foot numbness. Magnetic resonance imaging revealed multiple vertebral hemangiomas. One hemangioma at the T7 level demonstrated epidural extension, causing spinal cord compression. After treatment with radiotherapy, the patients symptoms improved significantly.
Asian Pacific Journal of Cancer Prevention | 2014
Kivanc Bektas-Kayhan; Gizem Karagöz; Mustafa Caner Kesimli; Ahmet Karadeniz; Rasim Meral; Musa Altun; Meral Ünür
BACKGROUND Carcinoma of the tongue is the most common intra-oral malignancy in Western countries. Incidence and mortality rates have increased in recent years, and survival has not improved. This study aimed to determine etiologic factors for tongue cancer with age-sex matched case-control data. MATERIALS AND METHODS 47 patients with carcinoma of the tongue referred to our oral medicine clinic between years 2005-2006 were analyzed and compared with control group data. The medical records , including family history of cancer, dental trauma, and history of abuse of alcohol and tobacco products was recorded for all subjects. Chi square comparison tests and linear regression analysis were performed using the SPSS program for statistics. RESULTS Patient and randomly selected control groups each consisted of 30 male and 17 female subjects with mean ages 53.2 (± 12.6) and 52.6 (± 11.5) years respectively. Smoking and alcohol abuse proportions were significantly higher in the patient group (p=0.0001, p<0.0001 respectively). Chronic mechanical trauma was observed in 44.7% of the patients and 17.0% of the control group (p=0.004). Similarly, family history of cancer of any type (for the first degree relatives) was found to be more common in the patient group (p=0.009). On regression analysis, alcohol abuse, family history of cancer, smoking, chronic mechanical traumas appeared as significant etiologic factors (p=0.0001). CONCLUSIONS We believe that field cancerization may become evident in oral and oropharyngeal mucosa with multiple steps of molecular changes starting from the first sign of dysplasia with chronic exposure to etiological factors. Chronic trauma cases need particular attention to search for very early signs of cancer.
Tumor Biology | 2016
Murat Guveli; Derya Duranyildiz; Ahmet Karadeniz; Elif Bilgin; Murat Serilmez; Hilal Oguz Soydinc; Vildan Yasasever
We aimed to determine the serum levels of angiogenic factors, namely angiopoietins, in nasopharyngeal and laryngeal carcinoma patients. We also aimed to seek the relation of these molecules with tumor grade and their utility as diagnostic biomarkers. We evaluated angiopoietin 1 and 2 levels innasopharynx and larynx cancer patients before treatment. Angiopoietin 2 levels were significantly elevated in larynx carcinoma patients and tended to be elevated in nasopharynx cancer patients compared with healthy controls. However, angiopoietin 1 levels were similar in cancer patients and controls. Angiopoietin 1 levels were significantly higher in nasopharyngeal cancer patients with advanced stages compared to earlier stages. On the other hand, angiopoietin 2 levels were similar in advanced and earlier stage cancer patients.
International Surgery | 2016
Kamuran Ibis; Ahmet Karadeniz; Rasim Meral; Murat Guveli; Mert Basaran; Sevil Bavbek; Meltem Ekenel; Fulya Yaman Agaoglu; Emin Darendeliler; Musa Altun
We designed our study to analyze the prognostic factors and treatment outcomes of adult medulloblastoma patients who received postoperative craniospinal irradiation. Fourty-three patients who were treated due to medulloblastoma at Istanbul University, Institute of Oncology between 1990 and 2013 were retrospectively analyzed. All of the patients were older than 18 years, with a median age of 27 years (range, 18–51 years). In 40 (93%) patients, total resection of the tumor was achieved, and 3 (7%) patients had undergone a subtotal tumoral resection. Risk assessment revealed 7 high-risk and 36 standard-risk patients. All patients received postoperative craniospinal irradiation, delivering a median craniospinal dose of 36 Gy, with an additional boost to the posterior fossa up to 54 Gy. Fifteen patients received chemotherapy. The median follow-up was 62 months (range, 3–213 months). The 5-year, 10-year, overall, and disease-free survival rates were 63%, 51%, 66%, and 55%, respectively. Univariate analysis reve...
International Journal of Oral and Maxillofacial Surgery | 2006
Gorkem Aksu; Ahmet Karadeniz; M. Saynak; M. Fayda; Z. Kadehci; H. Kocaelli