Patients
Medical records of patients with rectal cancer or sigmoid cancer who had undergone curative laparoscopic surgery between January 2008 and December 2014 at The Department of Gastrointestinal Surgery, Guangdong Provincial Hospital of Traditional Chinese Medicine were retrospectively reviewed. The following clinicopathological variables were retrieved from their medical records: demographic variables, surgery-related variables, pathological variables, postoperative complications, adjuvant chemotherapy, and follow-up variables.
Inclusion criteria were as follows: 20 years or older, pathologically confirmed adenocarcinoma of rectum or sigmoid colon, no distant metastasis, elective procedure, no history of abdominal surgery, and providing written informed consent. Clinical TNM staging was identified by combining results of colonoscopy, enhanced CT (thoracic, abdominal and pelvic) and/or magnetic resonance imaging (MRI).
Exclusion criteria included the following: synchronous or metachronous malignant tumors of other organs, multiple colorectal cancer in other segments of large bowel, acute intestinal obstruction or perforation caused by rectal cancer or sigmoid cancer, pregnant patients and patients lost during early follow-up. General conditions of all the patients were evaluated preoperatively by an experienced anesthesiologist from our center. Abdominoperineal resection, rectal intersphincteric resection and Hartmann,s operation were excluded from this study. This study was approved by The Ethical Committee of Guangdong Provincial Hospital of Traditional Chinese Medicine. All the patients had given his or her written informed consent. Declaration of Helsinki was adhered to during the whole process of this study[21].
Procedure
Surgeries were accomplished byadvanced general surgeons specialized in colorectal cancer surgery. All the surgeons accomplishing these surgeries had at least 10 years of clinical experience in tertiary hospitals. All the surgeries were performed according to Chinese guidelines on colorectal cancer[22, 23].
Previously, for patients with a giant tumor (6 cm or larger), conventional open surgery was preferred. However, in our study, all the patients underwent laparoscopic surgeries. All the laparoscopic surgeries were accomplished in a medial-to-lateral way. Firstly, we dissected lymph nodes around IMA and performed a retroperitoneal dissection. In the HT group, the IMA was divided and ligated at its origin from the abdominal aorta while for patients in the LT group, IMA was divided at the level of LCA branching and a simultaneous lymph node dissection around IMA was performed. Secondly, the left colon was mobilized. Thirdly, we cut the distal rectum using a linear stapler after irrigating the rectum. Fourthly, the removed specimen was taken out via a small incision after the proximal colon was cut approximately 10 cm from the cancer. The proximal margin was at least 10 cm while a distal margin of 3 cm was needed for cancer of the upper rectum and 2 cm for cancer of the lower rectum. The upper part of rectum was divided from the lower part of rectum by the peritoneal reflexion. Blood flow to the proximal colon stump in both arms was evaluated by performing a hemorrhage test of the marginal artery. Presence of palmic hemorrhage was indicative of sufficient blood supply. Resection of the proximal colon was not performed until confirmation of sufficient bleeding. Anvil of circular stapler was installed and fixed to the stump of the proximal colon. After the pneumoperitoneum was re-established, a pelvic sidewall lymphadenectomy was performed among patients with clinical T3 or deeper cancers with involvement of drainage lymph nodes identified by preoperative imaging examination. Finally, a double stapling technique was adopted to perform reconstruction. All the anastomotic reconstructions were accomplished in a straight fashion. After accomplishing reconstructions, we performed air leak tests to detect imperfections. Proximal colon of the anastomosis is closed using forceps after the circular stapler was fired. A small quantity of saline was put into the pelvic cavity and appearance of a bubble around the anastomosis was tested by pumping in air from the anus. If a bubble was detected, the anastomosis would be reinforced by the suture.
Surgeons in charge would decide whether a diverting stoma should be constructed among patients with a narrow male pelvic, positive result of air leak test, and an anastomotic level lower than 5cm from the anal verge. If a diverting stoma was not constructed, an intraluminal drainage tube would be inserted to decrease pressure within the anastomosis.
Adjuvant therapy
All patients with stage III cancer and II cancer with some high risk factors (such as microvascular invasion and nerve invasion) were recommended by surgeons in charge to receive postoperative adjuvant chemotherapy and patients who had given written informed consent subsequently underwent adjuvant chemotherapy. For stage III cancer, the regimen including oral fluoropyrimidine and oxaliplatin was preferred while oral fluoropyrimidine was recommended for stage II cancer. Neither preoperative nor postoperative radiotherapy was not routinely applied.
Follow-up
Unless otherwise contraindicated, all the patients were instructed to attend a recommended follow-up. The follow-up plan was made according to the Chinese guideline on CRC[21, 22]. For stage I CRC, the follow-up took place every six months for 5 years. While for stage II and III CRC, the follow-up took place every three months for the first three years then every six months for two more years. Five years after surgery, for stage II and III CRC, follow-up took place every one year for five years. The following aspects were included in follow-up regimens: physical examination, carcinoembryonic antigen (CEA) and cancer antigen 19-9 (CA-199), liver ultrasonography examination (stage I and II), contrast-enhanced CT (every one year, for colon cancer) or MRI (for rectal cancer, every one year), and colonoscopy (every one year for three years). Recurrence was confirmed by combining medical history, physical examination, CT or MRI examination, and histopathological examination was the ultimate diagnostic criterion whenever possible. Positron emission tomography-computed tomography (PET-CT) would be performed if recurrence was suspected but not confirmed by other examinations.
Assessment parameters
Preoperative parameters included the following ones:sex, age, body mass index (BMI), previous surgery history (mainly abdominal surgery) and concomitant disease (such as hypertension and diabetes mellitus). Operation-related parameters included the following aspects: date of operation, operation time, estimated blood loss (EBL), level of IMA ligation and blood transfusion. And parameters assessing cancer characteristics: histological component, differentiation, depth of invasion (T stage), lymph node metastasis (N stage) and pTNM stage. The following parameters assessing postoperative outcomes were retrieved: early and late complications, degree of complications, ICU stay, and length of hospital stay after surgery. Complications occurring within 30 days after surgery were defined as early complications while those occurred after 30 days were defined as late complications. Anastomotic fistula was detected by CT examination after finding of purulent discharge through the drainage tube or the presence of peritonitis. Complications were graded according to the Clavien–Dindo classification[24]. Overall survival (OS) was defined as the duration between curative surgery and death while the time length between curative surgery and cancer recurrence was defined as relapse-free survival (RFS). Both OS and RFS were calculated by performing the Kaplan-Meier analysis and corresponding differences betwen LT and HT group were compared using log-rank test. pTNM stages of all the patients were reassessed according to the eighth edition of International Union Against Cancer/American Joint Committee on Cancer (UICC/AJCC) TNM staging system for colorectal cancer. And for patients with CRC included in this study, at least 12 lymph nodes should be obtained.
Statistical analysis
Continuous variables were demonstrated as medians while categorical variables were presented as frequencies and percentages. Differences in proportions were evaluated by Chi-square test while significance of differences for continuous variables were assessed by Independent-Samples t test. Kaplan-Meier method was adopted to calculate OS and RFS and corresponding differences betwen LT and HT group were compared using log-rank test. Cox regression analysis (both univariate and multivariate) was performed to identify independent predictive factors for OS and RFS. P values less than 0.05 were recorded as statistically significant. Statistical Product and Service Solutions 22.0 (SPSS22.0, SPSS Inc, Chicago, IL) was used to performed statistical analyses involved in this study.