Ahmet Demirkazik

Ankara University, Ankara, Ankara, Turkey

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Publications (56)126.54 Total impact

  • Journal of endocrinological investigation 07/2014; 30(7):624-5. · 1.65 Impact Factor
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    ABSTRACT: Background: The ABO blood groups and Rh factor may affect the risk of lung cancer. Materials and Methods: We analyzed 2,044 lung cancer patients with serologically confirmed ABO/Rh blood group. A group of 3,022,883 healthy blood donors of Turkish Red Crescent was identified as a control group. We compared the distributions of ABO/Rh blood group between them. Results: The median age was 62 years (range: 17-90). There was a clear male predominance (84% vs. 16%). Overall distributions of ABO blood groups were significantly different between patients and controls (p=0.01). There were also significant differences between patients and controls with respect to Rh positive vs. Rh negative (p=0.04) and O vs. non-O (p=0.002). There were no statistically significant differences of blood groups with respect to sex, age, or histology. Conclusions: In the study population, ABO blood types were associated with the lung cancer. Having non-O blood type and Rh-negative feature increased the risk of lung cancer. However, further prospective studies are necessary to define the mechanisms by which ABO blood type may influence the lung cancer risk.
    Asian Pacific journal of cancer prevention: APJCP 05/2013; 14(5):2801-2803. · 1.50 Impact Factor
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    ABSTRACT: Background: Previous studies have observed an association between ABO blood group and risk for certain gastrointestinal malignancies, including pancreatic and gastric cancer. However, it is unclear whether there is such an association with colorectal cancer (CRC). In this study, possible relationships between ABO blood groups and Rh factor and KRAS status in patients with CRC were investigated. Materials and Methods: In 1,620 patients with CRC, blood group and Rh factor were examined and compared with the control group of 3,022,883 healthy volunteer blood donors of the Turkish Red Crescent between 2004 and 2011. The relationship of blood groups with wild type K-ras status was also evaluated. Results: Overall distributions of ABO blood groups as well as Rh factor were comparable between patients (45% A, 7.2% AB, 16.4% B, 31.4% O, and 87.2% Rh+) and controls (42.2% A, 7.6% AB, 16.3% B, 33.9% O, and 87.7% Rh+) (p=0.099). However, there were statistically significant difference between patients and controls with respect to O vs. non O blood group (p=0.033) and marginally significant difference for A vs. non-A blood group (p=0.052). Among patients, the median age was 62 (range 17-97), 58.1% were male. There were no statistically significant differences respect to sex and K-ras status. Conclusion: In present study, the ABO/Rh blood groups were statistically significantly associated with the risk of CRC. There were no relationship between K-ras status and ABO blood group and Rh factor. However further studies with larger numbers of patients are needed to establish the role of blood groups and to define the mechanisms by which ABO blood type affect CRC.
    Asian Pacific journal of cancer prevention: APJCP 12/2012; 13(12):6097-100. · 1.50 Impact Factor
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    ABSTRACT: Antimetabolites may cause severe toxicity and even toxic death in cancer patients. Our aim was to evaluate the relationship between antimetabolite toxicity and pharmacogenetics in patients with severe clinical toxicity or alanine transaminase (ALT) elevation after fluorouracil (5FU), capecitabine or methotrexate administration. Cancer patients with severe antimetabolite toxicity were evaluated for methylenetetrahydrofolate reductase (MTHFR) gene C667T, thymidilate synthase (TS) gene 5' UTR variable number of tandem repeats (VNTR), dihydroprymidine dehydrogenase (DPYD) gene IVS14+1G/A, Xeroderma pigmentosum (XPD) gene Lys751Gln and X-ray repair cross-complementing group 1 (XRCC1) gene Arg399Gln polymorphisms. Eighteen patients were enrolled, with a male/female ratio of 0.8. They had osteosarcoma in methotrexate group (n=7), gastrointestinal malignancies in 5FU group (n=9) and breast cancer in the capecitabine group (n=2). Mucositis and dermatitis occurred in all groups, together with ALT elevation in the methotrexate group and 2 toxic deaths were encountered. DPYD, TS, MTHFR, XPD and XRCC1 gene polymorphism rare allele frequencies were observed to be higher than in the general population. Pharmacogenetics might contribute to tailored therapy.
    Asian Pacific journal of cancer prevention: APJCP 01/2012; 13(4):1553-6. · 1.50 Impact Factor
  • European Journal of Cancer 09/2011; 47. · 4.82 Impact Factor
  • European Journal of Cancer 09/2011; 47. · 4.82 Impact Factor
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    ABSTRACT: This study was designed to assess the tolerability of chronomodulated infusion chemotherapy, individualized by the rhythm of peripheral blood cells. Twenty patients with metastatic gastric cancer were randomized to chronotherapy or day-time arms of 5-fluorouracil (FU) (600 mg/m2, 8 h inf.d1–5) and folinic acid (FA) (20 mg/m2, iv, d1–5) in the first cycle and crossed-over to the other arm in the following cycles. Ten of 18 evaluable patients were assigned to chronotherapy arm and eight to day-time in the first cycle. Although there was no significant difference between two arms on enrollment, chronotherapy arm yielded an improvement of 45% of QLQ-C30 scores (p = 0.021) and the day-time arm had 11% improvement (p = 0.575). After the crossing-over, chronotherapy arm, again, had a significant improvement in QLQ-C30 scores, compared to the day-time arm (14% vs. −18%, p = 0.001, respectively). Mucositis/diarrhea was significantly higher in the day-time arm compared to chronotherapy arm (p = 0.015). In conclusion, chronomodulated infusion of 5-FU might improve the quality of life.
    Biological Rhythm Research 11/2010; 35(4):259-268. · 1.22 Impact Factor
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    ABSTRACT: Kaposi sarcoma (KS) is a mesenchymal tumor originating from lymphatic endothelial cells. Immunosuppressive patients have higher risk for KS. HHV-8 has a role in immunopathogenesis of KS. Aim Evaluation of demographical properties with tumor characteristics and treatment modalities of KS. Histopathologically documented KS patients were evaluated retrospectively. Anti-HIV seroprevalence was also evaluated with patient and tumor characteristics besides treatment regimens. Fifty-one patients were included between September 1998 and February 2009. Male/female ratio was 3.25 (39/12). Median age was 68 (31-94). Lower extremity was the most common site whereas excisional biopsy was the most common diagnostic procedure. Smoking rate was 42.8%. Twenty percent had family history for cancer. Anti- HIV seropositivity rate was 1.9%. Thirty eight percent had local monotherapy, and radiotherapy was most common (26%). Multidisciplinary approach rate was 44%. Most of them had surgery and radiotherapy combination. Two-third of the patients had radiotherapy alone or with other modalities. Rates were as 12% for chemotherapy and 6% for interferon. Vincristine-bleomycin-doxorubicin combination was the most preferred regimen (60%). Male patients in the sixth decade seem to have higher risk for KS. Smoking rate was almost as high. Local therapy might be sufficient in most of the patients. However, we may also consider systemic chemotherapy for selected patients, including vincristine, bleomycin and doxorubicin.
    Clinical and Translational Oncology 09/2010; 12(9):629-33. · 1.28 Impact Factor
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    ABSTRACT: The aim of the study was to evaluate the relationship among leucocytosis, thrombocytosis and serum vascular endothelial growth factor (VEGF) levels and their prognostic value in patients with NSCLC. Fifty-five patients with histopathological and/or cytopathological diagnosed NSCLC were enrolled into the study. The patients were grouped as patients with leuco-cytosis (>10.000/mm 3) and/or thrombocytosis (>400.000/mm 3) (group 1), and others with none of them as a control group (group 2). Serum VEGF levels were measured by ELISA. Group 1 had three subgroups: patients with leucocytosis (group 1a), patients with thrombocytosis (group 1b) and patients with both of them (group 1c). Survival of the patients were analysed by Kaplan-Meier method. There was no survival difference between group 1 and 2, although there was a trend in favour of control group. The patients with higher levels of serum VEGF had a shorter survival than others who had lower lev-els, when the mean VEGF level of control group (206 pg/ml) was defined as cut-off value in group 1. The patients with leu-cocytosis and thrombocytosis had significantly higher VEGF levels when compared with control group (p= 0.022). No sur-vival difference was observed for groups 1a, 1b and 1c when compared with control group. In conclusion, serum VEGF lev-els were significantly higher in patients who had leucocytosis and/or thrombocytosis although leucocytosis and/or throm-bocytosis could not have been shown as a prognostic factor in patients with NSCLC. The association between serum VEGF and leucocytosis/thrombocytosis could not have been concluded as a cause or result.
    International Journal of Hematology and Oncology. 01/2010; 20(1):14.
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    ABSTRACT: In aggressive non-Hodgkin lymphoma (NHL), CHOP (cyclophosphamide, vincristine, doxorubicin, prednisolone) regimen has been standard for decades, and rituximab has increased response rates and survival in CD20 positive patients, recently. The aim of this prospective trial was to evaluate the long-term efficacy and toxicity of MINE as a consolidation treatment in aggressive NHL patients who had achieved CR or unproven CR after six cycles of CHOP in the first line setting. The primary end-point was disease-free-survival (DFS). Thirty-eight patients were enrolled between February 1992 and May 2000. All of the patients received two cycles of MINE (mesna 1.3 g/m(2), ifosfamide 1.3 g/m(2), etoposide 65 mg/m(2) on days 1-3, and mitoxantrone 12 mg/m(2) on day 1, every 3 weeks) following response to CHOP. Initial bulky disease sites were also applied radiotherapy. Male/female ratio was 1.53(23/15). Median age was 49(30-73). Most of the patients had advanced stage (84.2% for stage >3) and high IPI score (79% for IPI score >2). Sixty percent had diffuse large cell histology. Median follow-up time was 118 months (9-195). Actual mean dose intensity was 88%. There were seven febrile neutropenia episodes. Two patients had grade two neuropathy, one had grade three mucositis and another one had non-neutropenic pneumonia. There was no early toxic death. No serious late toxicity was observed during long-term follow-up. Five- and 10-year DFS rates were both 65.3%. DFS rate in the patients with more than two poor prognostic factors according to IPI score is remarkably high (88%). Five- and 10-year OS was 62.5 and 59%, respectively. MINE regimen seems to be effective as a consolidation regimen, especially, in intermediate/high risk patients and has low early and late toxicities, and it warrants to be evaluated in phase III randomised trials with rituximab in CD20 positive aggressive NHL patients.
    Medical Oncology 09/2009; 27(3):942-5. · 2.06 Impact Factor
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    ABSTRACT: Telomerase is a specialized cellular reverse transcriptase that adds telomeric repeats (TTAGGG) at the ends of each chromosome. Nearly the complete spectrum of human cancers has been shown to be telomerase positive. The understanding of the telomerase regulation in concert with other genetic alterations in the process of malignant transformation of human cells has important clinical and practical implications. Regulation of telomerase activity (TA) is highly complex, and both putative positive and negative regulators have been reported. However, the mechanisms involved in telomerase regulation are not fully established. Identification of additional telomerase components and associated proteins will certainly contribute to further investigations of the effect of telomerase in telomere elongation, telomere length maintenance, oncogenesis, and functionally new, unidentified cellular functions. In this study our aim was to determine the chromosomal localizations of putative unidentified telomerase activator(s) and/or repressor(s) by high resolution-comparative genomic hybridization (HR-CGH) in highly telomerase expressing gastric tumor samples. For this purpose TAs and genomic imbalances were identified in the same tumor samples and relation between these was evaluated. Genomic changes affecting telomerase activity in 50 gastric tumor samples were investigated by HR-CGH. We have found that genomic imbalances including 1q+, 8p+, 8q+, 10q+, 17p-, and 20p+ are associated with the higher telomerase activity. Our results suggest that 1q24, 8p21-p11.2, 8q21.1-q23, 10q21-qter and 20pter-p11.2 may contain putative telomerase activator(s), whereas the 17p12 region may harbor candidate telomerase suppressor(s).
    Oncology Research Featuring Preclinical and Clinical Cancer Therapeutics 02/2009; 17(10):455-62. · 0.92 Impact Factor
  • Cytopathology 02/2008; 20(2):117-20. · 1.47 Impact Factor
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    ABSTRACT: Sarcomas are heterogeneous groups of tumors that are seen rarely. Although great efforts have been made to identify prognostic factors apart from grade, histology and tumor size, they're not so obvious yet. In this study, the prognos-tic role of serum matrix metalloproteinase (MMP)-9 levels in patients with sarcoma was evaluated. Eighty-eight patients with a diagnosis of sarcoma were included in the study. Additionally in 14 patients with osteosar-coma, serum MMP-9 levels were analyzed twice, one in preoperative period during neoadjuvant chemotherapy and one in postoperative period. Sixteen healthy volunteers composed the control group. Serum MMP-9 levels have been evaluated quantitively by ELISA method. Serum MMP-9 levels were higher significantly compared to control group (p<0.005). Patients with metastatic disease have higher serum MMP-9 levels compared to the non-metastatic ones which were statistically non-significant (p: 0.9). Similarly, no difference in serum MMP-9 levels was observed between patients with intermediate-high grade tumors and with low grade tumors. Moreover, statistically significant decrease in serum MMP-9 levels was observed in patients in postoperative period compared to preoperative period (p: 0.016). Although this study was performed in small number and heterogeneous group of patients, the difference in serum MMP-9 levels between sarcoma patients and control group, especially in the presence of measurable lesions and in postoperative period of the same patients, suggests that serum MMP-9 levels may be used as a tumor marker in patients with sarcoma. ÖZET Sarkomlu Hastalarda Serum Matriks Metalloproteinaz-9 Düzeyinin Prognostik Değeri Sarkomlar oldukça nadir olarak gözlenen heterojen bir tümör grubudur. Tüm çabalara karşın tümör histolojisi, greydi ve tumor boyutu dışında bir prognostik faktör tayin edilememiştir. Bu çalışmada sarkomlu hastalarda serum matriks metalloproteinaz-9 (MMP-9) düzeyinin prognostik değeri araştırıldı.
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    ABSTRACT: There are few reports on use of symptomatic benefits as an alternative or adjunctive for the assessment of objective response in chemotherapy of the advanced cancer. This study is performed to assess the symptomatic benefits (the clinical benefit response), in addition to the efficacy and toxicity of cisplatin plus infusional 5-fluorouracil (5-FU) combination as second-line therapy in patients with advanced gastric cancer. Fifty-eight advanced gastric cancer patients with previous chemotherapy were enrolled into the study. Cisplatin 20 mg/m2 was given for 5 days, and 5-FU was given 1000 mg/m2 as 20 h continuous infusion for 5 days, repeated every 28 days. The overall objective response rate was 11.3%, and overall tumour control rate was 33.9%. The clinical benefit response, in terms of weight gain, reduction in analgesic consumption and the improvement in performance status observed in 12 patients [six patients with partial response (PR) and six patients with stable disease (SD)] (22.6%), while the rates of the clinical benefit response in patients with PR and with SD were 100% and 50% respectively. Cisplatin plus infusional 5-FU combination seems to improve disease-related symptoms (clinical benefit response) of patients with advanced gastric cancer, even in patients without objective response.
    European Journal of Cancer Care 12/2007; 17(1):26 - 32. · 1.31 Impact Factor
  • EJC Supplements 09/2007; 5(4):416-416. · 2.71 Impact Factor
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    ABSTRACT: In this non-randomized study we aimed to assess the efficacy of the addition of low molecular weight heparin (LMWH) to gemcitabine (GEM) plus cisplatinum (CDDP) combination chemotherapy on survival by prevention of thromboembolic complications in patients with advanced pancreatic cancer (APC). Between November 1999 and February 2004, 69 consecutive patients with APC were treated with GEM (800 mg/m2, day 1, day 8) plus CDDP (35 mg/m2, day 1, day 8) every 21 days +/-LMWH (nadroparine calcium, 2,850 IU/day until disease progression). Ten out of 35 patients in LMWH group and 10 out of 34 patients in chemotherapy alone group had primary inoperable locally advanced disease and the rest of the patients had metastatic disease. Total response rate was 58.8% (11.7% CR) for the patients treated with LMWH and 12.1% for those treated without LMWH (P = 0.0001). LMWH group had a better median time to progression (TTP) and survival when compared to control group (7.3 vs. 4.0 months, P = 0.0001; 13.0 vs. 5.5 months, P = 0.0001). The toxicity was similar and acceptable in both groups. Addition of LMWH to GEM plus CDDP combination significantly improved the response and survival in patients with APC and the current schedule deserves to be tested in phase III trials.
    Journal of Surgical Oncology 06/2007; 95(6):507-12. · 2.84 Impact Factor
  • Southern Medical Journal 03/2007; 100(3):334-5. · 1.12 Impact Factor
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    ABSTRACT: Malignant mesothelioma is a rare but notoriously chemoresistant tumor. An impressive activity of gemcitabine and cisplatin combination in malignant mesothelioma has been shown. However, the hematological toxicity and nephrotoxicity related to this regimen affect the patient's life negatively. The aim of this study is to investigate the efficacy and toxicity of divided dose of cisplatin combined with gemcitabine in chemo-naïve patients with malignant mesothelioma. Twenty-six eligible patients with malignant mesothelioma were enrolled onto the study. Cisplatin 35 mg/m(2) and gemcitabine 800 mg/m(2) were administered on days 1 and 8 as intravenous infusion in a 3-week cycle, up to maximum 6 cycles. Response and toxicity evaluations were performed in 26 patients. Male-female ratio was 11/15 with a mean age of 50.5 years (37-70). Locations of tumor were pleura in 16 patients, and peritoneum in 10 patients. All patients had epitheloid subtype of malignant mesothelioma. The partial response and stable disease were observed in 6 patients (23.1%) and in 13 patients (50%), respectively, with an overall tumor control rate of 73.1%. Seven patients (26.9%) had progressive disease. Median time to disease progression and survival were 4 and 19.5 months, respectively. Grade 3 nausea and vomiting were observed in one patient (3.8%), grade 4 neutropenia developed in one patient (3.8%) and grades 3-4 thrombocytopenia and nephrotoxicity did not develop. There was no treatment related death. Divided dose of cisplatin combined with gemcitabine, at the current dosage and schedule, appears to be an active regimen in chemotherapy-naïve patients with malignant mesothelioma, and well-tolerated.
    Lung Cancer 10/2006; 53(3):367-74. · 3.74 Impact Factor
  • Annals of Oncology 01/2006; 16(12):1981. · 6.58 Impact Factor
  • Mutlu Dogan, Ahmet Demirkazik
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    ABSTRACT: Venous thromboembolism (VTE) is a well-recognized problem in malignancy. Patients with cancer who have VTE have a worse prognosis than other patients with cancer. Hypercoagulability in patients with cancer is related to malignancy itself and its treatment. These patients have multiple risk factors for thromboembolism, such as being immobilized, having central venous catheters, and receiving chemoradiation therapy. Cancer procoagulant, tissue factor, factor VIII, and thrombin have important roles in causing cancer-associated thromboembolism. Tumors require neovascularization for delivering oxygen and other nutrients. Therefore, angiogenesis facilitates tumor growth, invasion, and metastasis. New blood vessels formed by angiogenesis are thrombogenic. Hypercoagulability and tumor growth are closely related. Vascular endothelial growth factor (VEGF) is a proangiogenic factor that may also cause VTE in patients with cancer. The relationship between cancer, angiogenesis, VEGF, and thrombosis is reviewed herein. Studies are ongoing to enhance our understanding of this complex interaction.
    Supportive Cancer Therapy 10/2005; 3(1):28-34.

Publication Stats

304 Citations
126.54 Total Impact Points


  • 1999–2012
    • Ankara University
      • • Department of Medical Oncology
      • • Department of Internal Medicine
      Ankara, Ankara, Turkey
  • 2008
    • Dicle University
      • Division of Medical Oncology
      Amida, Diyarbakır, Turkey
  • 1993–1998
    • Ibn Sina Hospital Dhanmondi
      Baghdād, Mayorality of Baghdad, Iraq