Ozkan Kanat - Academia.edu (original) (raw)

Papers by Ozkan Kanat

Turkiye Klinikleri Journal of Surgical Medical Sciences, 2006

Medical Oncology, 2013

Metastatic gastric cancer is incurable and remains one of the leading causes of cancer-related de... more Metastatic gastric cancer is incurable and remains one of the leading causes of cancer-related deaths around the world. Despite the significant progress in its systemic treatment, metastatic gastric cancer is still a major therapeutic challenge for oncologists. Newer chemotherapy regimens and the addition of molecularly targeted agents to chemotherapy seem to provide better clinical outcomes for patients with metastatic gastric cancer. The objective of this article is to review the current treatment approach for this formidable disease.

NeuroReport, 2013

Recent studies have demonstrated that arginine vasopressin (AVP) plays a crucial role in pain mod... more Recent studies have demonstrated that arginine vasopressin (AVP) plays a crucial role in pain modulation. In addition, our previous studies have proven that centrally administered cytidine-5 0-diphosphate-choline (CDPcholine; citicoline) elicits an analgesic effect in different pain models in rats. Given that CDP-choline enhances central and peripheral vasopressin levels, the present study was designed to investigate the role of central AVP receptors in the analgesic effect of CDP-choline in acute and chronic constriction injury-induced neuropathic pain models. For this purpose, rats were pretreated intracerebroventricularly with the AVP V 1 or AVP V 2 receptor antagonist 15 min before intracerebroventricular injection of CDP-choline or saline, and pain threshold was determined using the Randall-Selitto test. AVP V 1 and AVP V 2 receptor antagonist blocked the CDP-choline-induced analgesic effect either in acute or neuropathic models of pain in rats. These results suggest, for the first time, that central AVP receptors are involved in the CDP-cholineelicited analgesic effect.

Nephrology, 2006

Although the association and causality between chronic inflammatory states and systemic AA amyloi... more Although the association and causality between chronic inflammatory states and systemic AA amyloidosis have been well established, the evidence linking solid malignancies to reactive AA amyloidosis is scarce. Here, a case of diagnosed AA amyloidosis associated with synchronous carcinomas of stomach and bladder complicated with nephrotic syndrome and renal failure is reported.

Bu çalışmada, İmatinibe dirençli gastrointestinal stromal tümörlü (GİST) hastalarda sunitinipin e... more Bu çalışmada, İmatinibe dirençli gastrointestinal stromal tümörlü (GİST) hastalarda sunitinipin etkinliği araştırıldı. Gereç ve Yöntem: Tıbbi tedavileri ve sonuçları hakkında yeterli bilgi elde edilebilen, imatinibe dirençli GIST'i olan toplam 11 hasta retrospektif olarak değerlendirildi. Bulgular: Sadece 2 hastada kısmi yanıt ve beş hasta da stabil hastalık gözlendi. Progresyonsuz sağkalım süresi ve genel sağkalım süresi sırasıyla 12 ay ve 8.8 ay olarak bulundu. Sunitinip genellikle iyi tolere edildi. Hemen hemen tüm hastalarda bir veya daha çok tedavi ilişkili yan etki gözlendi. Tartışma: Sınırlı deneyimimize dayanarak, imatinib dirençli hastaların tedavisinde sunitinipin etkin bir tedavi seçeneği olduğunu düşünüyoruz.

Bursa Devlet Hastanesi Bülteni, 2004

Ileri evre pankreas kanserli hastalar kotu bir prognoza sahiptir ve tedavileri medikal onkoloji p... more Ileri evre pankreas kanserli hastalar kotu bir prognoza sahiptir ve tedavileri medikal onkoloji pratiginde onemli bir problem olmaya devam etmektedir. Bu nedenle bu calismada metastatik veya lokal ileri pankreas kanseri tanisiyla tedavi edilen hastalarimizin klinik ozelliklerini ve tedavi sonuclarini retrospektif olarak degerlendirmeyi amacladik. Bu calisma icin, Ocak 1995-Mayis 2012 tarihleri arasinda tedavi edilen ve klinik bilgileri elde edilebilen toplam 183 olgunun dosyasini retrospektif olarak inceledik. Hastalarin demografik ozelliklerini, almis olduklari tedavileri ve sagkalim sonuclarini belirledik. Olgularin 123'u erkek, 60'i kadin olup ortanca yas 60 (33-84) idi. Tani aninda 105 olgu metastatikti ve en sik metastaz yeri karacigerdi. Yetmis bes hasta gemsitabin + 5-Fluorourasil, 42 hasta gemsitabin, 24 hasta gemsita-bin+sisplatin ve 3 hasta UFT+sisplatin ile tedavi edilmisti. Kemoterapi ile olgularin %6'sinda tam yanit, %8.7'de kismi yanit ve %9.8'de st...

Tumori Journal, 2006

Aims and background To evaluate the efficacy and tolerability of a new treatment approach includi... more Aims and background To evaluate the efficacy and tolerability of a new treatment approach including induction chemotherapy (CT) and concurrent chemoradiotherapy (CRT) in unresectable, locally advanced pancreatic cancer (LAPC). Patients and methods Twenty-four patients with LAPC were enrolled in the study. They first received induction CT consisting of 5-fluorouracil (5FU) (500 mg/m2) and gemcitabine (1000 mg/m2), which were given weekly for 3 weeks of every 4. Patients showing a response or disease stabilization after 2 cycles of induction CT received CRT consisting of external beam radiotherapy (50.4-54 Gy in fractions of 1.8 Gy/day) and gemcitabine (350 mg/m2, weekly for 6 weeks). Patients without disease progression received 2 additional cycles of CT consisting of 5FU plus gemcitabine with the same doses and schedule as given in the induction CT. Results After the end of the study, 2 (8%) and 5 (21%) patients showed complete and partial responses, respectively. Five patients (21%...

Tumori Journal, 2004

AimTo determine the activity and toxicity of a combination of weekly gemcitabine and 5-fluorourac... more AimTo determine the activity and toxicity of a combination of weekly gemcitabine and 5-fluorouracil bolus intravenously in patients with metastatic pancreatic cancer.Patients and methodsTwenty-one patients with previously untreated metastatic pancreatic cancer were included in this phase II study. The schedule was gemcitabine (1000 mg/m2iv) and 5-fluorouracil (500 mg/m2bolus iv) weekly for 3 weeks every month.ResultsFour patients (19%) achieved a partial response and three stable disease. A clinical benefit was obtained in 7 patients (33%). Median survival for all the patients was 6 months. The treatment was well tolerated and toxicity was mild. WHO grade 3 leukopenia occurred in 2 (9.5%) patients, grade 3 anemia in 4 (19%) patients, grade 3-4 thrombocytopenia in 4 (19%) patients, grade 1 diarrhea in 1 (4.7%) patient and grade 1 mucositis in 3 (14.2%) patients.ConclusionThe weekly administration of gemcitabine combined with 5-fluorouracil bolus iv is an active and well-tolerated reg...

Tumori Journal, 2003

Aim To investigate the activity and toxicity of irinotecan (CPT-11) as a single agent in patients... more Aim To investigate the activity and toxicity of irinotecan (CPT-11) as a single agent in patients with advanced gastric cancer after failure of previous 5-fluorouracil-based combination chemotherapy. Patients and methods Sixteen patients with advanced gastric received CPT-11, 350 mg/m2 every 21 days. The median age of the patients was 54.6 years; ECOG performance status was 0-1 in 14 patients and 2 in 2 patients. Dominant metastatic sites included liver, lung, lymph nodes and peritoneum. Results No complete response was observed. Two patients (12.5%) achieved a partial response to treatment. One patient (6.25%) had a minor response. Ten patients (62.5%) had progressive disease on therapy, and 3 patients (18.75%) had stable disease. The median survival of all 16 patients was 5 months. Grade 3 neutropenia was observed in 3 patients (18.75%), grade 4 thrombocytopenia in 1 patient (6.25%), and grade 3 anemia in 1 patient (6.25%). Three patients (18.75%) suffered from grade 3 diarrhea. C...

Journal of Clinical Oncology, 2011

e14668 Background: Gastric cancer (GC) is one of the leading causes of cancer mortality worldwide... more e14668 Background: Gastric cancer (GC) is one of the leading causes of cancer mortality worldwide. 18F-FDG PET may have a role in predicting patient prognosis on the basis of the metabolic activity of primary tumors (PT). We retrospectively evaluated prognostic value of FDG-PET/CT in metastatic gastric cancer. METHODS This was a retrospective analysis of 75 patients with metastatic G who attended chemotherapy units of the participating centers from January 2007 to June 2010 and underwent FDG PET/CT imaging before the first line chemotherapy. RESULTS Median age in our study group was 62 and 25 of them were women. Median follow-up was 10 months. The patients received either ECF (n=16) or TCF (n=47) or cisplatin and capesitabine (n=12). Both PFS and OS were significantly higher in the ECOG PS 0 and 1 group of patients (n=58) compared to ECOG PS 2 (n=17; 6 vs 4 months, p= 0.032) and 13 vs 8 months, p= 0.002 respectively). 57 patients were adenocarcinoma while signet ring cell type were diagnosed in 18 patients. Median PFS and OS were 5 and 11 months respectively. Median SUV max value (>8.6) for the PT was significantly associated with both PFS (6 vs 4 months, , p= 0.04, HR: 0.45 (0.21-0.98) and OS (16 vs 8 ay, HR: 0.40 [0.17-0.90] p= 0.03). Median highest SUV max value (>7) for distant metastasis (DM) was not correlated with PFS (p= 0.7) and OS (p= 0.1). When the correlation between median SUV max for each metastatic site with PFS and OS were assessed, only liver metastasis had a significant association with OS; (15 vs 7.5 months, HR: 0.18 [0.07-0.46] p= 0.0003). In multivariate analysis ECOG PS (p=0.0015), SUV max of the primary tumor sites (p=0.02) and metastatic liver lesions (p= 0.00001) remained as significant predictors for poor OS. CONCLUSIONS In metastatic gastric cancer PET CT is a useful instrument for predicting poor prognosis. High FDG uptake of primary tumor site and metastatic liver lesions are significantly associated with shorter OS.

The Turkish Journal of Gastroenterology, 2011

Involvement of the gastrointestinal (GI) tract by malignant fibrous histiocytoma (MFH) as a metas... more Involvement of the gastrointestinal (GI) tract by malignant fibrous histiocytoma (MFH) as a metastatic site is rare (1-3). We present herein a case of MFH metastasizing to the sigmoid colon (SC), which is an extremely rare metastatic location for this tumor, with synchronous local recurrent ...

Acta orthopaedica Belgica, 2014

Patients with a newly detected solitary bone metastasis and no history of cancer need extensive d... more Patients with a newly detected solitary bone metastasis and no history of cancer need extensive diagnostic testing. One hundred and twenty biopsy samples of patients with metastatic bone disease were referred to the authors' pathology department between June 2005 and December 2012. Thirty-three (27.5%) of these patients with a solitary metastasis of unknown origin, and without visceral metastases, were studied retrospectively. Most metastases were found in the spine (14/33 or 42.4%), or in the pelvis (7/33 or 21.2%). The lung was the most common primary site, but this is not universal in the literature. A useful flowchart for the clinician, confronted with a bone metastasis from an unknown primary site, is the following, according to the literature: history and physical examination, biochemistry with tumor markers and immunoelectrophoresis, chest radiograph, CT-scan of chest and abdomen, and bone scan.

Neoplasma, 2005

There are conflicting data about the effects of cisplatin on erythropoietin (EPO) response to ane... more There are conflicting data about the effects of cisplatin on erythropoietin (EPO) response to anemia. Aim of our study was to investigate whether endogenous EPO response to anemia in cisplatin treated patients was insufficient in comparison to the anemic chemotherapy-naive cancer patients and non cancer patients with iron deficiency anemia. Patients who had hemoglobin (Hb) levels of less than 110 g/l were included in the study. Fifteen chemotherapy- naive cancer patients were enrolled in Group A. Group B consisted of 15 patients who had been treated with three cycles of cisplatin chemotherapy and then became anemic and in Group C were included 15 patients who had iron deficiency anemia, without any malignancy. The mean Hb values were not different between all groups (102.8+/-39.8 g/l, 103.1+/-2.5 g/l and 99.3+/-3.6 g/l in Group A, Group B and Group C, respectively). However, EPO levels were found to be significantly lower in Group A and Group B than Group C (29.63+/-9.09 mU/ml, 20.8...

Hepato-gastroenterology

H. pylori-induced hyperproliferation of the gastric epithelium may have a critical role in gastri... more H. pylori-induced hyperproliferation of the gastric epithelium may have a critical role in gastric carcinogenesis. H. pylori-related hyperproliferation and reversibility of hyperproliferation after eradication therapy is still controversial. Therefore, we have evaluated the effects of H. pylori and its eradication on gastric antral epithelial proliferation. A total of 32 H. pylori-positive and 22 H. pylori-negative subjects were enrolled into the study. Triple eradication therapy was given to the H. pylori-positive group. Upper endoscopy was repeated one month after the therapy and six months later, antral biopsy specimens were taken in each endoscopy. Biopsy specimens from H. pylori-negative subject were taken at the beginning of the study and sixth months later also. Proliferative index was 40.2% in H. pylori-positive state; it regressed to 27.6% after eradication and six months later the proliferative index was 30.7%. H. pylori-negative group's proliferative index was 25.5% i...

The American Journal of Gastroenterology, 2006

We have two critical comments to the paper of Dr. Moayyedi and Achkar (1) on a pooled analysis of... more We have two critical comments to the paper of Dr. Moayyedi and Achkar (1) on a pooled analysis of the efficacy of colorectal cancer screening by fecal occult blood testing (FOBT). First, there is a disagreement in mortality from other causes in the Scholefield et al. study (2) between the risk ratio (RR) reported in Figure 2 (RR 1.03) and that computed by the data reported in Table 1 (RR 1.0078, rounded to 1.01). As the study is considered the largest in the reanalysis, such a difference would greatly influence the overall estimate toward the null value. Second, Moayyedi et al. considered the Minnesota trial results at 13 yr of follow-up, in order to compare them with the two European randomized trials (2, 3). We wonder why they did not choose the results of the Minnesota trial at a longer (18 yr) follow-up (4), which would make results more stable and reliable. If these results had been considered, reanalysis outcome would be substantially different. In fact, colorectal cancer mortality at 18 yr was reduced by 21% (RR 0.79, 95% CI 0.62-0.97), and overall screening efficacy estimates at reanalysis would be increased. Also, cumulative mortality from other causes at 18 yr was the same (biennal screening 328.8, control arm 328.9). Based on the results of well-designed controlled clinical trials, which thus far have been accepted as valuable evidence by the scientific community, colorectal cancer screening by FOBT is recommended and implemented as a standard policy in developed countries, which implies that a tremendous economical effort is under way, and great expectations have been induced at a population level. Although we appreciate that critical reanalysis of evidence-based health policies is performed as a standard practice, this should be done with extreme caution and precision, and critical papers should be as rigorous as the studies they criticize.

Journal of Cancer Research and Therapeutics, 2014

Surgery is the definitive treatment for early colon cancers. Adjuvant therapies are used with the... more Surgery is the definitive treatment for early colon cancers. Adjuvant therapies are used with the aim of eradicating micrometastases and improving cure rates. Recent studies have proposed that adiponectin might be responsible for obesity-related malignancies. We investigated the prognostic value of this cytokine. Patients who underwent surgical removal of stage II or III (TNM staging) primary tumors and were followed for at least three years were included in the study given adequate specimen for immunohistochemical evaluation. Based on these criteria, 53 patients were included. Mean age was 58.3 ± 10.1 years (35-78 years). The mean follow-up time was 41 months (10-96 months). Immunohistochemical evaluation identified 21 patients (39.6%) with cytoplasmic adiponectin present in their specimens. The rates of recurrence were 42.9% (9/21) and 34.4% (11/32) in patients with and without adiponectin expression, respectively. In cases with adiponectin expression, mean disease - free survival was 60.3 ± 9.03 months, and in cases without adiponectin expression, mean disease - free survival was 68.7 ± 6.67 months (P = 0.414). Mean overall survival of patients with adiponectin expression was 65 months compared to 67 months for patients without (P = 0.786). Adiponectin, which is secreted by adipose tissue, may have a role in the development and progression of cancer via its pro-apoptotic and/or anti-proliferative effects. Adiponectin expression in tumor tissues is likely to have a negative effect on disease - free survival in patients with stage II/III colon cancer; however, no statistically significant effect was demonstrated.