• Outcomes of Conversion from Laparoscopy to Open Surgery in Geriatric Patients with Colorectal Cancer: A Case Controlled Study Okkabaz N, Yılmaz M, Civil O, Haksal M, Oncel M. J BUON. 2019;24(5):1809-1816
  In this series where we examined the transition from laparoscopic surgery to open method in colon cancer surgery, we observed a higher incidence of conversion to open method in patients aged 70 and older, resulting in the development of some complications at a greater rate. However, from an oncological perspective, we did not detect any issues.
• Hand-Crafted Endoluminal Vacuum-Assisted Drainage for Anastomotic Leak After IPAA. Okkabaz N, Esen E, Schwartzberg DM, Remzi FH, Kirat HT. Dis Colon Rectum. 2019;62(10):1259-1262
  Our technical article describes the method we developed to reduce the cost of the current treatment used in the colonoscopic treatment of anastomotic leaks in patients with leakage following Ulcerative Colitis surgery. We successfully apply this method in cases of leaks occurring after rectal cancer surgery as well.
  
  
• Necrotising fasciitis of the thigh caused by duodenum invasion of renal cell carcinoma: A case report. Okkabaz N, Turgut MA. Int Wound J. 2019;16(5):1195-1198
  We presented the surgical treatment of an infection caused by the perforation of the duodenum (the first part of the small intestine) by a kidney tumor, leading to the retroperitoneal (the back part of the abdomen) passage of intestinal contents and its presence in the thigh.
  
  
• Safety of primary anastomosis following emergency left sided colorectal resection: an international, multi-centre prospective audit. 2017 European Society of Coloproctology (ESCP) collaborating group. Colorectal Dis. 2018;20 Suppl 6:47-57
  A study conducted by the European Society of Coloproctology (ESCP) in 2017, derived from a multicenter study to which we provided data.
  
  
• Association of mechanical bowel preparation with oral antibiotics and anastomotic leak following left sided colorectal resection: an international, multi-centre, prospective audit. 2017 European Society of Coloproctology (ESCP) collaborating group. Colorectal Dis. 2018;20 Suppl 6:15-32
  The study conducted by the European Society of Coloproctology (ESCP) in 2017, in which we provided data, is a multicenter research project.
  
  
• The impact of conversion on the risk of major complication following laparoscopic colonic surgery: an international, multicentre prospective audit. 2017 and 2015 European Society of Coloproctology (ESCP) collaborating groups. Colorectal Dis. 2018;20 Suppl 6:69-89
  A study conducted by the European Society of Coloproctology (ESCP) in 2017, derived from a multicenter investigation to which we contributed data.
  
  
• An international multicentre prospective audit of elective rectal cancer surgery; operative approach versus outcome, including transanal total mesorectal excision (TaTME). 2017 European Society of Coloproctology (ESCP) collaborating group. Colorectal Dis. 2018;20 Suppl 6:33-46
  A study conducted by the European Society of Coloproctology (ESCP) in 2017, derived from a multicenter research project to which we contributed data.
  
  
• Evaluating the incidence of pathological complete response in current international rectal cancer practice: the barriers to widespread safe deferral of surgery. 2017 European Society of Coloproctology (ESCP) collaborating group. Colorectal Dis. 2018;20 Suppl 6:58-68
  A study conducted by the European Society of Coloproctology (ESCP) in 2017, derived from a multicenter research project to which we contributed data.
  
  
• J-pouch vs. side-to-end anastomosis after hand-assisted laparoscopic low anterior resection for rectal cancer: A prospective randomized trial on short and long term outcomes including life quality and functional results. Okkabaz N, Haksal M, Atici AE, Altuntas YE, Gundogan E, Gezen FC, Oncel M. Int J Surg. 2017;47:4-12
  In this study, we evaluated two different anastomosis (intestinal connection) methods aimed at preventing the progression of symptoms such as gas and fecal incontinence, diarrhea attacks, and constant toilet need that can occur after rectal cancer surgery. We did not observe a functional difference between the two methods; however, as additional information, we found that the anastomosis was more secure in patients who underwent lateral end anastomosis.
  
  
• Fortune of temporary ileostomies in patients treated with laparoscopic low anterior resection for rectal cancer. Haksal M,Okkabaz N, Atici AE, Civil O, Ozdenkaya Y, Erdemir A, Aksakal N, Oncel M. Ann Surg Treat Res. 2017;92(1):35-41
  We observed that in approximately 15% of patients who underwent laparoscopic low anterior resection and stoma placement due to rectal cancer, the stoma could not be closed. The most significant reason was the development of anastomotic stricture. Interestingly, some patients expressed satisfaction with their stomas and chose not to undergo closure despite no apparent obstacles. In modern times, there are also patients who do not undergo stoma (ostomy/ileostomy) creation after rectal cancer surgery.
  
  
• The Feasibility of Hepatic Resections Using a Bipolar Radiofrequency Device (Habib®). O Civil, M Kement, N Okkabaz, M Haksal, C Gezen, M Oncel. Indian J Surg. 2015;77(4):276-82
  We observed that the bipolar radiofrequency device, which we used in liver resection cases, including liver metastases, reduced intraoperative blood loss but increased the risk of postoperative abscess formation. Nowadays, in addition to the classic clamping-crushing method for liver resections, we also benefit from technological devices.
  
  
• Safety and feasibility of laparoscopic sigmoid colon and rectal cancer surgery in patients with previous vertical abdominal laparotomy. Haksal M, Ozdenkaya Y, Atici AE, Okkabaz N, Aksakal N, Erdemir A, Civil O, Oncel M. Int J Surg. 2015;21:97-102
  We demonstrated that the laparoscopic method can be safely applied in patients with sigmoid colon and rectal cancer who had previously undergone abdominal surgery with midline incision. We observed that laparoscopic colon resection in previously operated patients did not increase complications during and after surgery.
  
  
• Preoperative functional health status may predict outcomes after elective colorectal surgery for malignancy. Isik O, Okkabaz N, Hammel J, Remzi FH, Gorgun E. Surg Endosc. 2015;29(5):1051-6
  We observed that the preoperative functional status of American patients undergoing colon and rectal cancer surgery could adversely affect postoperative outcomes. Individuals who partially or completely relied on someone else’s support to perform their daily activities (such as eating, dressing, toileting, etc.) before surgery experienced more postoperative complications compared to those who did not require any support. Therefore, improving the overall health condition of patients identified during the preoperative waiting period could reverse the negative outcomes after surgery.
  
  
• Interesting Localizations of Primary Hydatid Cysts. Aksakal N, Kement M, Altuntas YE, Okkabaz N, Oncel M. Ulus Cerrahi Derg. 2015;32(2):130-3
  A series in which we demonstrated that hydatid cysts, also known as dog cysts colloquially, and mostly found in the liver or in conjunction with other organs, can also be present in organs other than the liver. Our goal is to encourage our colleagues to consider hydatid disease when they observe cysts in any organ, even if there is no cyst in the liver.
  
  
• Risk factors for early postoperative morbidity and mortality in patients underwent radical surgery for gastric carcinoma: a single center experience. Vural S, Civil O, Kement M, Altuntas YE, Okkabaz N, Gezen C, Haksal M, Gundogan E, Oncel M. Int J Surg. 2013;11(10):1103-9
  In a study where we examined risk factors for early complications after stomach cancer surgery, we observed that uncontrolled additional diseases such as lung and heart diseases, hypertension, diabetes, and being over 70 years old could negatively impact postoperative outcomes.
  
  
• Ramadan fasting in patients with a stoma: a prospective study of quality of life and nutritional status. Altuntas YE, Gezen FC, Sahoniz T, Kement M, Aydin H, Sahin F, Okkabaz N, Oncel M. Ostomy Wound Manage. 2013;59(5):26-32
  In our study investigating the impact of Ramadan fasting on the nutritional status and quality of life of patients with ostomy due to cancer, we observed a slight decrease in the nutritional parameter called prealbumin in those with ostomy who fasted compared to those with ostomy who did not fast. However, we found that their quality of life did not decrease. Stoma patients in good health can choose to fast if they wish.
  
  
• Laparoscopic and Conventional Resections for Low Rectal Cancers: A Retrospective Analysis on Perioperative Outcomes, Sphincter Preservation, and Oncological Results. Gezen C, Altuntas YE, Kement M, Aksakal N, Okkabaz N, Vural S, Oncel M. J Laparoendosc Adv Surg Tech A. 2012;22(7):625-30
  Regardless of the method applied, it was observed that in cases of rectal cancer located 6 cm from the anal verge, where the operation requires serious expertise, laparoscopic surgery resulted in less bleeding during the operation and a reduced need for blood transfusion after surgery. Sphincter-preserving surgery could be applied at a higher rate in cases treated laparoscopically. Laparoscopic surgery can be effectively applied in distal rectal cancer patients without adversely affecting oncological outcomes.
  
  
• The role of group education on quality of life in patients with a stoma. Altuntas YE, Kement M, Gezen C, Eker HH, Aydin H, Sahin F, Okkabaz N, Oncel M. Eur J Cancer Care (Engl). 2012;21(6):776-81
  We observed that providing education in large groups consisting of family members and other patients with stomas, rather than one-on-one education during discharge, increased the quality of life and social adaptation for cases with ileostomy, colostomy, or urostomy stomas. We recommend centers with stomatherapy units and nurses to organize similar activities.
  
  
• Safety and Effectiveness of 5-mm and 10-mm Electrothermal Bipolar Vessel Sealers (LigaSure) in Laparoscopic Resections for Sigmoid Colon and Rectal Cancers. Gezen C, Kement M, Altuntas YE, Aksakal N, Okkabaz N, Civil O, Vural S, Oncel M. J Laparoendosc Adv Surg Tech A. 2012;22(6):572-7
  In a study examining the impact of size differences in commonly used energy devices during laparoscopic colon and rectum cancer surgery on potential adverse outcomes during and after the operation, it was observed that there was no significant difference between 5mm and 10mm devices. Despite being less preferred during the period of the study, 5mm devices are now routinely used by many teams.
  
  
• Laparoscopy for sigmoid colon and rectal cancers in septuagenarians: a retrospective, comparative study. Altuntas YE, Gezen C, Vural S, Okkabaz N, Kement M, Oncel M. Tech Coloproctol. 2012;16(3):213-9
  In a study comparing open and laparoscopic surgery in patients aged 70 and above undergoing sigmoid colon and rectum cancer surgery, it was demonstrated that laparoscopic surgery can be safely applied in elderly patients as effectively as in younger individuals. Additionally, it was observed that outcomes were better in elderly patients undergoing laparoscopic surgery compared to open surgery. In conclusion, laparoscopic colorectal surgery can be safely performed in elderly patients.
  
  
• Complete versus partial mobilization of splenic flexure during laparoscopic low anterior resection for rectal tumors: a comparative study. Gezen C, Altuntas YE, Kement M, Vural S, Civil O, Okkabaz N, Aksakal N, Oncel M. J Laparoendosc Adv Surg Tech A. 2012;22(4):392-6
  Adhesions to the posterior abdominal wall are often accompanied by adhesions to the lower part of the colon, particularly to the spleen. During rectal cancer surgery, instead of the removed intestine, these adhesions need to be freed, essentially elongating the colon. For this purpose, liberation of the splenic flexure (splenic corner) can be partially or fully performed. In our study, we observed that when complete liberation is carried out, a longer segment of the intestine can be obtained for the anastomosis, thereby increasing the chance of creating a J-pouch or side-to-end reservoir. In our team, complete mobilization of the splenic flexure is consistently performed in all rectal and sigmoid colon cancer cases where anastomosis is planned.
  
  
• Results after multivisceral resections of locally advanced colorectal cancers: an analysis on clinical and pathological T4 tumors. Gezen C, Kement M, Altuntas YE, Okkabaz N, Seker M, Vural S, Gumus M, Oncel M. World J Surg Oncol. 2012;15;10:39
  In cases of colon and rectum cancer with invasion into surrounding tissues (tumor progression), we demonstrated that partially or completely removing all organs to which the tumor adheres during surgery, without causing tumor dissemination to these organs, is as effective as surgery applied to less advanced tumors, despite increasing bleeding and blood needs during the operation. Therefore, in cases of cancer that have progressed to surrounding organs, experienced hands should perform a comprehensive multi-organ resection.
  
  
• Laparoscopic abdominoperineal resections for mid or low rectal adenocarcinomas: a retrospective, comparative study. Gezen C, Altuntas YE, Kement M, Okkabaz N, Bilici A, Vural S, Gumus M, Oncel M. Surg Laparosc Endosc Percutan Tech. 2011;21(6):396-402
  We have demonstrated that in patients with lower rectal cancer undergoing abdominoperineal resection, laparoscopic surgery is as safe as open surgery. Therefore, we believe that laparoscopic surgery should be considered as the first choice in abdominoperineal resection cases to provide the known advantages of laparoscopic surgery.
  
  
• Apical lymph nodes at the root of the inferior mesenteric artery in distal colorectal cancer: an analysis of the risk of tumor involvement and the impact of high ligation on anastomotic integrity. Alici, M. Kement, C. Gezen, T. Akın, S. Vural, N. Okkabaz, E. Basturk, A. Yegenoglu, M. Oncel. Tech Coloproctol 2010;14:1-8
  In a study conducted for rectum and distal sigmoid colon cancer surgery, where the risk of lymph node metastasis is present, we observed lymph node spread in up to 6% of patients when the vessel (inferior mesenteric artery) was ligated at its root. Therefore, we believe that high ligation of the vessel should be routinely applied due to the risk of lymph node metastasis.
  
  
• Left inferior quagrant oblique incision :a new access for hand-assisted device during laparoscopic low anterior resection of rectal cancer. Oncel M, Akın T ,Gezen FC, Alıcı A, Okkabaz N. J. Laparoendosc Adv Surg Tech. 2009;19:663-6
  A method we defined during the early stages of laparoscopic colorectal surgery in our country, also implemented by our team, involves placing the hand inside the abdomen for hand-assisted laparoscopic colorectal surgery. Currently, we perform all operations entirely laparoscopically without the need for manual assistance.