Through retrospective analysis of the clinical data of colorectal cancer from March 2006 to March 2014 in our department (Gastrointestinal Surgery, The First Hospital Affiliated to Yangtze University), a total of 414 patients, including 253 cases of colon cancer, 51 cases of transverse colon cancer, were consecutively admitted for operation. Twenty-five cases with carcinoma in the middle of transverse colon were analyzed. 12 cases underwent assisted laparoscopic radical resection (laparoscopic group), 13 cases underwent conventional open radical resection (open group) (Table 1). Post operative systemic chemotherapy was applied to patients with the visceral peritoneum metastasis and regional lymph node metastasis. Pathologic confirmation, colonoscopy, barium enema, computed tomography (CT), ultrasonography, and chest PA were performed for diagnosis in all patients pre-operatively.

Inclusion criteria in this study: 1) radical resection with carcinoma in the middle of transverse colon, 2) pre-operative diagnosis of malignant neoplasm of transverse colon was clear, 3) without distant metastasis through pre-operative examination, 4) R₀ resection by pathological examination.

Exclusion criteria in this study: 1) the emergency operation case (acute obstruction, perforation), 2) conversion to open surgery due to bleeding or surrounding organs damage during dissection or adhesion of surrounding tissue.

The human subject research review board of our institution approved our study protocol. Before treatment, informed consent was obtained from each patient.

Both laparoscopic surgery and open surgery strictly follow the tumor radical principle: 1) the complete mesocolic excision (CME) with central vein ligation (CVL) [17] [18] , 2) reconstruction of bowel [19] : If the colonic intestine was long enough, direct anastomosis of bowel without tension was done by end-to-end or end to side anastomosis (end to end anastomosis for loose intestinal loop, Figure 1(a). When colonic intestine is slightly tight after intestinal anastomosis, debonding of flexure duodenojejunalis can relieve the oppression to jejunum (additional debonding of flexure duodenojejunalis for slightly tight intestinal loop, Figure 1(b)). In the more obese patients or intestinal loop is thick and short bowel patients, in order to reduce the tension of anastomosis and the oppression to jejunum, penetration method (colon to be anastomosed through the small mesenteric root) is performed (penetration method for thick and short intestinal loop, Figure 1(c)).

Laparoscopically assisted radical operation:

1) Position of patient: supine, legs apart in order to facilitate the operation. Adjusting the patient position during the operation: reverse trendelenburg position with 20 degree tilt to right side for dissecting hepatic flexure of colon, reverse trendelenburg position with 20 degree tilt to left side for dissecting splenic flexure of colon; reverse trendelenburg position when dissecting transverse colon in the middle.

2) Position of Trocar: using five hole method, put the camera into abdominal cavity through 12 mm Trocar below the umbilicus, the remaining four holes are respectively placed in the left anterior axillary line 2 cm below the subcostal region with 12 mm trocar and left midclavicular line at level of umbilicus with 5 mm Trocar, the position of right upper and right lower trocar to the corresponding left side, using 5 mm Trocar. But during surgery the position of trocar

can be adjusted according to the location of tumor. Pneumoperitoneum is induced with CO₂ at 12 mmHg.

3) The dissecting process starts with vascular root: After abdominal cavity is explored, greater omentum and transverse colon are pushed to the side of head, small intestine is pushed to the left abdominal cavity, then the mesenteric root is exposed, peritoneal incision is commenced with dissection along the superior mesenteric vein up to the inferior margin of pancreas. Middle colic artery, a branch of superior mesenteric artery, usually found in inferior margin of pancreas is clipped with Ham-Lock clamp and transected at the root along with the middle colic vein. Lymph nodes of the anterior aspect of superior mesenteric vein from middle colic vessels to the gastro-colic trunk of Henle are dissected. A fascial plane between the mesocolon and the underlying retroperitoneum, formed by the fusion of the visceral peritoneum of the mesocolon with the parietal peritoneum of the retroperitoneum is known as Toldt’s fascia [20] . During the surgery, dissection along the plane between the intact dorsal mesocolon of the hepatic flexure and the Fredet preduodenopancreatic fascia was done. Then, dissection was done along the duodenal plane into the pancreatic surface, turning left along the pancreatic surface into lesser sac, exposing the tail of the pancreas and the lower pole of the spleen. From the middle of the gastrocolic ligament, besides gastroepiploic vessels arch, greater omentum was dissected towards the hepatic flexure of colon and splenic flexure of colon respectively. Hepatic flexure was mobilized by dissecting the lateral peritoneal fold, the superior attachment (right phrenocolic ligament), and the medial attachment (cholecysto-duodeno-colic ligament). Splenic flexure is mobilized by dissecting the gastrocolic and splenocolic ligament.

4) Resection and Anastomosis: Once the colon was completely mobilized, an incision of about 5 - 6 cm was made in the mid line of the upper abdomen. Incision protractor was used. Then the mass was extracted along with the colon. En bloc resection of mass with the omentum and mesentery lymph nodes was done. A stapled colo-colic anastomosis was done with either end-to-end or end-to-side anastomosis.

5) The colon was then placed back into the abdomen and extraction site was closed. CO₂ was reinsufflated to create pneumoperitoneum, operated area was irrigated with saline water. The drainage tube was placed nearby foramen of Winslow. Open operation was done with the same method with middle approach, which was same to laparoscopic group.

1) Intra-operative observation indexes: operation time, bleeding volume, the number of dissected lymph nodes.

2) Post-operative recovery indexes: flatus time, liquid food intake time, ambulation time, hospitalization time.

3) Post-operative complication: complication that develops as any adverse event after treatment, including incision site infection, abdominal bleeding, intra-abdominal infection, anastomotic fistula, intestinal obstruction and re-hospitalization within 30 days. Treatment mortality is defined as any death within 30 days of the treatment.

4) Follow-up: Patient’s five-year overall survival observed. Post-operative follow-up: every 3 - 6 months for 2 years, then every 6 months for a total of 5 years.

Continuous data were expressed as range and the mean ± SD and were compared between groups by using the Independent-Samples T Test. Categorical variables were compared by using the χ² test. Overall survival was computed by using the Kaplan-Meier method and was compared between the two groups by using the log-rank test. All statistical analyses were performed with the SPSS statistical package (SPSS 20.0 for Windows). A P value < 0.05 was considered statistically significant.

The baseline characteristics of the patients in both groups are shown in Table 1. The two groups were similar in age and sex distribution. There was no significant difference between the groups in Pathological staging and differentiation of adenocarcinoma (poorly/moderately/well by using 2010 World-Health-Organization criteria [21] ).

The Intra-operative observation indexes are shown in Table 2. In laparoscopic group, 12 patients were successfully performed assisted laparoscopic radical resection for mid transverse colon cancer, without conversion to laparotomy. Operation time was 200 - 300 min (230 ± 28.60 min), the bleeding volume was 50 - 150 ml (89.58 ± 32.99 ml), intra-operative dissected lymph nodes number were 15 - 39 pieces (22.25 ± 6.48). In Open group, 13 patients were successfully

performed open radical resection for mid transverse colon cancer. Operation time was 160 - 270 min (213.85 ± 33.55min), the bleeding volume was 70 - 200 ml (133.46 ± 44.51 ml), intra-operative dissected lymph nodes number were 13 - 25 pieces (17.53 ± 3.75). Operation time in laparoscopic group was longer than the open surgery group, but there was no significant difference in two groups (p > 0.05). Intra-operative bleeding volume in laparoscopic group was obviously less than the open group (p < 0.05). The number of dissected lymph nodes were more than open surgery group (p < 0.05).

The post-operative recovery indexes are shown in Table 3. Post-operative flatus time, liquid food intake time, ambulation time and hospitalization time in laparoscopic group were 2 - 5 d (3.00 ± 1.12 d), 3 - 6 d (3.91 ± 0.99 d), 1 - 6 d (3.33 ± 1.43 d) and 7 - 11 d (9.50 ± 1.24 d) respectively. Post-operative flatus time, liquid food intake time, ambulation time and hospitalization time in open group were 3 - 7 d (4.76 ± 1.16 d), 4 - 8 d (5.00 ± 1.15 d), 3 - 7 d ( 4.61 ± 1.12 d) and 10 - 16 d (12.00 ± 1.82 d) respectively.

Index of post-operative recovery in laparoscopic group including post-operative flatus time, liquid food intake time, ambulation time and hospitalization time were shorter than the open group (P < 0.05).

One case with post-operative incision site infection was found in open group. Abdominal bleeding, intra-abdominal infection, anastomotic fistula, intestinal obstruction weren’t found in two groups. There wasn’t re-hospitalization and dead case in 30 d post-operative period in two groups.

Five patients (41.7%) in laparoscopic group and six patients (46.2%) in open group had died in 5-year follow-up. Figure 2 depicts the cumulative five-year overall survival curves, which were not significantly different between two groups (P = 0.8547).