Objective To investigate the clinical efficacy of radical resection of rectal cancer with different surgical approaches and influencing factors of postoperative complications.

Methods The retrospective study was conducted. The clinicopathological data of 3 418 patients who underwent radical resection of rectal cancer in the Second Affiliated Hospital of Harbin Medical University from July 2011 to September 2020 were collected. There were 2 060 males and 1 358 females, aged (61±11)years. Patients meeting the requirements of radical resection and surgical indications underwent surgeries choosing from open radical colorectal cancer surgery, laparoscopic radical colorectal cancer surgery, and natural orifice specimen extraction surgery (NOSES). Observation indicators: (1) intraoperative and postoperative conditions of patients undergoing different surgical approaches; (2) comparison of preoperative clinical characteristics in patients undergoing different surgical approaches; (3) comparison of postoperative histopathological characteristics in patients undergoing different surgical approaches; (4) postoperative complications of patients undergoing different surgical approaches; (5) analysis of influencing factors of postoperative complications. Measurement data with normal distribution were represented as Mean±SD. Measurement data with skewed distribution were represented as M(range), and comparisons between groups was analyzed using the Kruskal-Wallis rank test. Comparison of ordinal data was analyzed using the non‐parameter rank sum test. Count data were described as absolute numbers or percentages, and comparison between groups was analyzed using the chi‐square test. Multivariate analysis was conducted using the Logistic regression model.

Results (1) Intraoperative and postoperative conditions of patients undergoing different surgical approaches. Of the 3 418 patients, 1 978 cases underwent open radical colorectal cancer sur-gery, 1 028 cases underwent laparoscopic radical colorectal cancer surgery and 412 cases underwent NOSES, respectively. The operation time, volume of intraoperative blood loss, cases with permanent stoma, preventive stoma or without fistula, time to postoperative first flatus, time to postoperative liquid food intake, cases transferred to intensive care unit after surgery, duration of postoperative hospital stay were 145(range, 55‒460)minutes, 100(range, 30‒1 000)mL, 435, 88, 1 455, 72(range, 10‒220)hours, 96(range, 16‒296)hours, 158, 10(range, 6‒60)days, respectively, in patients undergoing open radical colorectal cancer surgery. The above indicators were 175(range, 80‒450)minutes, 50(range, 10‒800)mL, 172, 112, 744, 48(range, 14‒120)hours, 72(range, 38‒140)hours, 17, 9(range, 4‒40)days, respectively, in patients undergoing laparoscopic radical colorectal cancer surgery and 180(range, 80‒400)minutes, 30(range, 5‒500)mL, 0, 45, 367, 48 (range, 14‒144)hours, 72(range, 15‒148)hours, 1, 6(range, 3‒30)days, respectively, in patients undergoing NOSES. There were significant differences in the above indicators among the patients undergoing different surgical approaches (H=291.38, 518.56, χ²=153.82, H=408.86, 282.97, χ²=78.66, H=332.30, P<0.05). (2) Com-parison of preoperative clinical characteristics in patients undergoing different surgical approaches. The gender, age, body mass index, cases with diabetes, cases with hypertension, cases with coronary heart disease, cases with anemia, cases with hypoproteinemia, cases with intestinal obstruction, tumor location, preoperative carcinoembryonic antigen, preoperative CA19‑9 showed significant differences among patients undergoing open radical colorectal cancer surgery, laparoscopic radical colorectal cancer surgery and NOSES (P<0.05). (3) Comparison of postoperative histopathological characteris-tics in patients undergoing different surgical approaches. Tumor histological type, tumor differentiation degree, tumor diameter, number of lymph node detected, nerve invasion, vascular invasion, lymph node invasion, tumor T staging, tumor N staging, tumor M staging, tumor TNM staging showed significant differences among patients undergoing open radical colorectal cancer surgery, laparos-copic radical colorectal cancer surgery and NOSES (P<0.05). (4) Postoperative complications of patients undergoing different surgical approaches. Cases with postoperative complications as anastomotic leakage, abdominal infection, intestinal obstruction, anastomotic bleeding, incision complications, pulmonary infection, other complications were 52, 21, 309, 8, 130, 51, 59, respectively, in patients undergoing open radical colorectal cancer surgery. The above indicators were 33, 17, 75, 3, 45, 58, 9, respectively, in patients undergoing laparoscopic radical colorectal cancer surgery and 13, 4, 8, 0, 11, 10, 15, respectively, in patients undergoing NOSES. There were significant differences in the intes-tinal obstruction, incision complications, pulmonary infection, other complications among patients undergoing different surgical approaches (χ²=122.56, 13.33, 20.44, 15.59, P<0.05) and there was no significant difference in the anastomotic leakage, abdominal infection, anastomotic bleeding among patients undergoing different surgical approaches (χ²=0.96, 2.21, 3.08, P>0.05). (5) Analysis of influencing factors of postoperative complications. ① Analysis of influencing factors of intestinal obstruction in patients with radical resection of rectal cancer. Age as 20‒39 years and 40‒59 years, surgical approach as laparoscopic radical colorectal cancer surgery and NOSES were independent protective factors of intestinal obstruction in patients with radical resection of rectal cancer (odds ratio=0.46, 0.59, 0.43, 0.13, 95% confidence interval as 0.21‒1.00, 0.36‒0.96, 0.33‒0.56, 0.06‒0.27, P<0.05). ② Analysis of influencing factors of incision complications in patients with radical resection of rectal cancer. Body mass index as 24.0‒26.9 kg/m², surgical approach as laparoscopic radical colorectal cancer surgery and NOSES were independent protective factors of incision complications in patients with radical resection of rectal cancer (odds ratio=0.24, 0.63, 0.46, 95% confidence interval as 0.11‒0.51, 0.44‒0.89, 0.24‒0.87, P<0.05). ③ Analysis of influencing factors of pulmonary infection in patients with radical resection of rectal cancer. The surgical approach as laparoscopic radical colorectal cancer surgery was an independent risk factor of pulmonary infection in patients with radical resection of rectal cancer (odds ratio=2.15, 95% confidence interval as 1.46‒3.18, P<0.05), and tumor TNM staging as 0‒Ⅰ stage was an independent protective factor (odds ratio=0.10, 95% confidence interval as 0.01‒0.88, P<0.05). ④ Analysis of influencing factors of other complica-tions in patients with radical resection of rectal cancer. Age as 20‒39 years, 40‒59 years, 60‒79 years, body mass index as <18.5 kg/m², 18.5‒23.9 kg/m², 24.0‒26.9 kg/m², 27.0‒29.9 kg/m², surgical approach as laparoscopic radical colorectal cancer surgery were independent protective factors of other complications in patients with radical resection of rectal cancer (odds ratio=0.10, 0.29, 0.37, 0.08, 0.22, 0.35, 0.32, 0.29, 95% confidence interval as 0.01‒0.81, 0.13‒0.64, 0.17‒0.78, 0.02‒0.40, 0.09‒0.52, 0.15‒0.83, 0.12‒0.89, 0.14‒0.59, P<0.05).

Conclusions Compared to laparoscopic radical colorectal cancer surgery and NOSES, open radical colorectal cancer surgery has wide indication and short operation time, but less perioperative treatment effect. Laparoscopic radical colorectal cancer surgery and NOSES can achieve better surgical result and less postoperative complication when patients meeting surgical indications.