Mesocolon

Clinicopathological features studied included the following 13 factors: sex, age at surgery, tumor location, tumor size, histology, lymphovascular invasion, lymph node metastasis, number of lymph nodes retrieval, surgical procedure, postoperative complications, postoperative adjuvant chemotherapy, preoperative serum carbohydrate antigen 19-9 (CA19-9) level and carcinoembryonic antigen (CEA) level.
All the patients underwent curative colonectomy plus complete mesocolic excision and lymph node dissection. The tumors were staged according to the eighth edition of the UICC TNM classification system. Tumors were classified into two groups based on WHO two-tier classification of histology grade: low grade and high grade. The indications of postoperative adjuvant chemotherapy included stage III patients and stage II patients with high risk factors for recurrence, such as poor histological differentiation, lymphovascular invasion, perineural invasion, preoperative bowel obstruction, and less than 12 lymph nodes examined, etc. However, whether the patients eventually received postoperative adjuvant chemotherapy was based on the patient's willingness, age, comorbid underlying diseases, physical status and pathological stages.

According to Finnish healthcare policy, all municipalities are responsible for arranging specialized hospital care for their residents. Each hospital district organizes and provides specialized hospital care for the population in its area. The Central Hospital of Central Finland is the only gastroenterological surgery unit in the Central Finland hospital district. The annual population of the area was obtained from Statistics Finland, and averaged around 270 000 during the study period, from 1 January 2000 to 31 December 2015. All patients with primary and metastatic colorectal cancer are managed in this hospital, with no referrals to other hospitals.
Patients diagnosed with primary colorectal cancer during the study interval were identified using the histopathological registry of the hospital, which covers all colorectal cancers diagnosed in the area. Clinical and histopathological data, as well as recurrence data, were retrieved retrospectively from hospital records. Colonoscopy, thoracoabdominal CT, endorectal ultrasonography and pelvic MRI were used to diagnose and stage primary colorectal tumours. All patients with colorectal primary and metastatic disease were discussed in multidisciplinary team (MDT) meetings before definitive treatment decisions were
made.
Surgery for primary colorectal cancers was performed according to international guidelines3, mostly with a laparoscopic approach, complete mesocolic and total mesorectal excision principles. Liver surgery was performed according to international guidelines4, 5, using intraoperative ultrasound imaging, a cavitron ultrasonic surgical aspirator and bipolar energy devices. After 2011, lung metastases were treated primarily with a thoracoscopic approach using wedge resection or segmentectomy. Tumours were staged by staff pathologists according to the UICC/TNM classification14.
Neoadjuvant and adjuvant treatments for primary and metastatic disease were administered according to international guidelines3. Since 2005, adjuvant postoperative chemotherapy for 6 months, consisting of 5‐fluorouracil (5‐FU) and oral folic acid, oral capecitabine or folic acid, 5‐FU and oxaliplatin (FOLFOX regimen), was prescribed to medically fit patients with stage III tumours or high‐risk stage II disease. Patients with liver metastases received perioperative chemotherapy with the FOLFOX regimen, with or without biologicals, according to the decision taken at the MDT meeting.
Surgery for advanced disease was performed when appropriate, according to the local MDT. Significant co‐morbidity and inadequate physical and mental performance status were contraindications for surgery. Unresectable metastatic disease was defined as the inability to achieve complete resection of all metastases, liver and lung metastases combined with more than one extrahepatic site, extensive extrahepatic metastatic disease, inability to leave at least 30–40 per cent of functional liver volume in the case of liver metastases, and progression of metastatic disease during chemotherapy.
The study was approved by the hospital administrative and ethics board (Dnro13U/2011 and 1/2016) and the National Authority for Welfare and Health (Valvira) (Dnro 3916/06.01.03.01/2016).

The computer searches the web of science and CNKI. The search period is from the establishment of the database to August 2022. The search adopts the combination of free words and subject words and uses the literature tracking method to find relevant literature. The search terms in the English database include “mesocolon excision” and “laparoscopy”; The search terms in the Chinese database include “mesocolon excision,” “laparotomy” and “laparoscopy.”

The inclusion criteria are as follows: ① the study design type is a randomized controlled trial or quasirandomized controlled trial. ② The study subjects in the literature were patients with mesocolon excision. ③ The surgical methods used by the experimental group in the literature include laparoscopic assisted treatment and Da Vinci intelligent robot assisted ④ the outcome indicators include the number and situation of postoperative complications.
Exclusion criteria are as follows: ① documents without full text, incomplete information or unable to extract data. ② Duplicate publication. ③ Minutes of meeting.