Study on the Risk of Incisional Hernia Development Following Transverse Epigastric Incisions in Patients Operated for Malignant Tumors

RESEARCH PROJECT OBJECTIVES The aim of the presented scientific project is to establish the factors, with special reference to the type of surgical technique, tissue accumulation of advanced glycation end products, and collagen content in transversalis fascia, associated with development of incisional hernia after transverse incision in the epigastric region in patients operated for malignant tumors WORK PLAN This study is planned as a prospective evaluation of factors associated with the development of incisional hernias after transverse incisions in the epigastric region in patients undergoing surgical treatment of malignant tumors of the alimentary system. The main hypothesis of this study, which forms the basis for sample size calculations, is the presence of an association between application of mass continuous abdominal closure and reduction of the risk of incisional hernia from 35% down to 20% as compared to layered continuous suture. Using a threshold for the level of type I error of 0.05 and a threshold for the probability of type II error on the level of 20%, the total number of patients who should be included in the study is 284 (142 patients in either of the 2 arms). However, considering the approximate value of 2-year patient survival of 20% and a further 10% rate of losses to follow-up, the study is planned to include a cumulative number of 392 patients (196 in either of the two arms).

The primary end-point of this study is the development of burst abdomen in the immediate postoperative period (until discharge from hospital) or incisional hernia over a 2-year follow-up period (combined end-point). The follow-up protocol used for the assessment of incisional hernias at discharge from hospital and two control visits at 1 and 2 years postoperatively. Evaluation of the presence of incisional hernia will, in each case, be based upon both clinical and ultrasonographical examination.

The primary factor that will be assessed for potential association with the development of incisional hernias is the surgical technique applied for abdominal closure. The technique comprising continuous suture and mass closure (one layer of sutures involving peritoneum, transversalis fascia, posterior and anterior layer of rectus abdominis muscle fascia and potentially, fascia of the oblique abdominal muscles) will be compared to the technique 2 separate layers of continuous sutures involving peritoneum, transversalis fascia, and posterior layer of rectus abdominis muscle fascia (first layer), and anterior layer of rectus abdominis muscle fascia and potentially, with oblique abdominal muscles fascia (second layer), respectively. Patients will be randomly assigned to one of the two arms in a 1:1 ratio basing on drawing a sealed envelope with code specific for the type of intervention. Neither the patients included in the study nor the investigators assessing the presence of incisional hernia during follow-up visits will be aware of the type of surgical technique used for abdominal closure (double-blinded study).

Only the professionals present in the operating room during surgical procedure, including operator, assistants, anesthesiologist, and nurses, will be aware of the type of assigned intervention. Besides the type of surgical technique and independent of random assignment to one of the two arms of the study, all included patients will be subject to the assessment of accumulation of advanced glycation end products within the skin and collagen in general, type I collagen and type III collagen within the transversalis fascia in order to evaluate potential associations between these factors and occurrence of the primary end-point. Analyses on the influence of the type of surgical technique used for abdominal closure, accumulation of advanced glycation end products, and collagen content within the transversalis fascia on the risk of incisional hernia formation will be adjusted for the effects of remaining known risk factors, including: age, sex, weight, height, primary disease being an indication for the procedure, history of previous hernia, history of previous abdominal operations, preoperative chemotherapy, cigarette smoking, excessive alcohol intake, presence of liver disease, obesity, arterial hypertension, chronic obstructive pulmonary disease, heart failure, anemia, race, width of subcutaneous adipose tissue, particular type and length of the incision, intraoperative transfusions of packed red blood cells, and occurrence of surgical site infection in the postoperative period.

Analyses concerning the primary end-point of the study will be performed 2 years after the date of surgical procedure in the last patient included in the study cohort. Additionally, an early analysis only with respect to the occurrence of burst abdomen is planned to be done 30 days after the date of surgical procedure in the last patient included in the study cohort. Independently of the primary end-point, separate analyses will be performed to evaluate the impact of the analyzed factors and the occurrence of incisional hernias on the quality of patients' life.