Researcher:
Bayram, Onur

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Doctor

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Onur

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Bayram

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Bayram, Onur

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2016 - 201922020 - 20212

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    Robotic complete mesocolic excision versus conventional laparoscopic hemicolectomy for right-sided colon cancer
    (Mary Ann Liebert, Inc, 2019) Yozgatli, Tahir K.; Aytac, Erman; Ozben, Volkan; Baca, Bilgi; Hamzaoglu, Ismail; Karahasanoglu, Tayfun; Bayram, Onur; Gürbüz, Bülent; Balık, Emre; Buğra, Dursun; Doctor; Doctor; Faculty Memeber; Faculty Memeber; N/A; N/A; School of Medicine; School of Medicine; Koç University Hospital; N/A; N/A; 18758; 1758
    Background: Robotic technique has been proposed to overcome the limitations of laparoscopic surgery. In this study, we aimed at determining whether robotic complete mesocolic excision (CME) for right-sided colon cancer can be safe and effective as conventional laparoscopic right hemicolectomy (CLRH). Materials and Methods: Between February 2015 and September 2017, patients undergoing robotic right CME and CLRH with curative intent for right-sided colon cancer were included. Patient characteristics, short-term and histopathological outcomes were compared between the groups. Results: Ninety-six patients (robotic, n = 35) were included in this study. The operative time (286 -77 versus 132 -40 minutes, P = .0001) was significantly longer in the robotic group. There were no conversions in either group. No significant differences existed between the groups regarding the mean estimated blood loss, time to first flatus, length of hospital stay (6 -3 versus 6 -3 days, P = .64), and follow-up times (robotic 15 +/- 8 versus laparoscopic 16 +/- 10 months P = .11). Overall complication rates (n = 10 [29%] versus n = 15 [25%], P = .67) were similar. In the robotic group, vascular injury occurred in 2 patients, and both were repaired robotically. The mean number of harvested lymph nodes was significantly higher (41 +/- 12 versus 33 +/- 10, P = .04) and length between the vascular tie and colonic wall was longer (13 +/- 3.5 versus 11 +/- 3, P = .02) in the robotic group. Conclusion: Although robotic right CME seems equally safe to CLRH in terms of short-term morbidity, future prospective randomized trials are needed to define its role for treatment of right colectomy.
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    PublicationOpen Access
    Minimally invasive versus open surgery for gastric cancer in Turkish population original article
    (Bilimsel Tıp Yayınevi, 2021) Tarcan, Serim; Aytaç, Erman; Zenger, Serkan; Benlice, Çiğdem; Özben, Volkan; Baca, Bilgi; Hamzaoğlu, İsmail; Karahasanoglu, Tayfun; Ağcaoğlu, Orhan; Şengün, Berke; Bayram, Onur; Balık, Emre; Buğra, Dursun; Faculty Member; Undergraduate Student; Faculty Member; Faculty Member; School of Medicine; Koç University Hospital; 175476; N/A; N/A; 18758; 1758
    Objective: in this study, it was aimed to compare short-term outcomes of minimally invasive and open surgery for gastric cancer in the Turkish population carrying both European and Asian characteristics. Material and Methods: short-term (30-day) outcomes of the patients undergoing minimally invasive and open gastrectomy with D2 lymphadenectomy for gastric adenocarcinoma between January 2013 and December 2017 were compared. Patient demographics, history of previous abdominal surgery, comorbidities, short-term perioperative outcomes and histopathological results were evaluated between the study groups. Results: there were a total of 179 patients. Fifty (28%) patients underwent minimally invasive [laparoscopic (n= 19) and robotic (n= 31)] and 129 (72%) patients underwent open surgery. There were no differences between the two groups in terms of age, sex, body mass index and ASA scores. While operative time was significantly longer in the minimally invasive surgery group (p< 0.0001), length of hospital stay and operative morbidity were comparable between the groups. Conclusion: while both laparoscopic and robotic surgery is safe and feasible in terms of short-term outcomes in selected patients, long operating time and increased cost are the major drawbacks of the robotic technique preventing its widespread use.
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    PublicationOpen Access
    Multiparametric MRI of rectal cancer-repeatability of quantitative data: a feasibility study
    (Aves, 2020) Gürses, Bengi; Altınmakas, Emre; Böge, Medine; Aygün, Murat Serhat; Bayram, Onur; Balık, Emre; Faculty Member; Other; Faculty Member; School of Medicine; N/A; N/A; N/A; N/A; N/A; 18758
    Purpose: in this study, we aimed to analyze the repeatability of quantitative multiparametric rectal magnetic resonance imaging (MRI) parameters with different measurement techniques. Methods: all examinations were performed with 3 T MRI system. In addition to routine sequences for rectal cancer imaging protocol, small field-of-view diffusion-weighted imaging and perfusion sequences were acquired in each patient. Apparent diffusion coefficient (ADC) was used for diffusion analysis and k(trans) was used for perfusion analysis. Three different methods were used in measurement of these parameters; measurements were performed twice by one radiologist for intraobserver and separately by three radiologists for interobserver variability analysis. ADC was measured by the lowest value, the value at maximum wall thickness, and freehand techniques. K-trans was measured at the slice with maximum wall thickness, by freehand drawn region of interest (ROI), and at the dark red spot with maximum value. Results: a total of 30 patients with biopsy-proven rectal adenocarcinoma were included in the study. The mean values of the parameters measured by the first radiologist on the first and second measurements were as follows: mean lowest ADC, 721.31 +/- 147.18 mm(2)/s and 718.96 +/- 135.71 mm(2)/s; mean ADC value on the slice with maximum wall thickness, 829.90 +/- 144.24 mm(2)/s and 829.48 +/- 149.23 mm(2)/s; mean ADC value measured by freehand ROI on the slice with maximum wall thickness, 846.56 +/- 136.31 mm(2)/s and 848.23 +/- 144.15 mm(2)/s; mean k(trans) value on the slice with maximum wall thickness, 0.219 +/- 0.080 and 0.214 +/- 0.074; mean k(trans) by freehand ROI technique (including as much tumoral tissue as possible), 0.208 +/- 0.074 and 0.207 +/- 0.069; mean k(trans) measured from the dark red foci, 0.308 +/- 0.109 and 0.311 +/- 0.105. Intraobserver agreement was very good among diffusion and perfusion parameters obtained with all three measurement techniques. Interobserver agreement was very good, except for one of the measurement techniques. As far as interobserver variability is considered, only ADC value measured on the slice with maximum wall thickness differed significantly. Conclusion: multiparametric MRI of rectum, using ADC as the diffusion and k(trans) as the perfusion parameter is a repeatable technique. This technique may potentially be used in prediction and evaluation of neoadjuvant treatment response. New studies with larger patient groups are needed to validate the role of multiparametric MRI.
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    PublicationOpen Access
    The role of MRI with diffusion-weighted imaging in restaging rectal cancers after neoadjuvant chemoradiotherapy
    (AOSIS Publishing, 2016) Bayram, İrem; Bakır, Barış; Kartal, Merve G. D.; Kunduz, Enver; Türkay, Rüştü; Aşoğlu, Oktar; Kapran, Yersu; N/A; Bayram, Onur; School of Medicine
    Background: It is challenging to restage rectal cancer at MRI, in patients who have had neoadjuvant chemoradiotherapy. Objective: To investigate the accuracy of MRI with diffusion-weighted imaging (DWI) in the restaging of rectal cancer. Materials and methods: Pre- and post-neoadjuvant chemoradiotherapy MRI examinations of 35 patients diagnosed with locally advanced rectal cancer were evaluated and subsequently compared with post-operative pathology results. Results: The accuracy of MRI with DWI to determine the T-stage status was calculated as 54.28%. Kappa statistics revealed poor concordance with pathology results, with a. value of 0.212 +/- 0.114 (p = 0.028). The apparent diffusion coefficient (ADC) values measured after the neoadjuvant chemotherapy revealed a significant increase when compared with pre-treatment ADC values (p < 0.000001). MRI accuracy rate for lymph node involvement was calculated as 57.14% with a. value of 0.001 (p = 0.989). MRI had 80% sensitivity and 100% specificity in determining mesorectal fascia involvement, with a calculated positive predictive value of 100% and a calculated negative predictive value of 96%. The accuracy of MRI in overall staging according to the TNM staging system was 28%. Conclusion: The accuracy of MRI in restaging rectal cancer is not yet sufficient and is not on par with the accuracy of MRI in the primary staging of the disease. This is attributed to post-treatment changes. Adding DWI to the protocol is promising, but more expanded data are required.