[Risk factors of postoperative surgical site infection in colon cancer based on a single center database]

Objective: To explore the incidence and risk factors of postoperative surgical site infection (SSI) after colon cancer surgery. Methods: A retrospective case-control study was performed. Patients diagnosed with colon cancer who underwent radical surgery between January 2016 and May 2021 were included, and demographic characteristics, comorbidities, laboratory tests, surgical data and postoperative complications were extracted from the specialized prospective database at Department of General Surgery, Peking Union Medical College Hospital. Case exclusion criteria: (1) simultaneously multiple primary colon cancer; (2) segmental resection, subtotal colectomy, or total colectomy; (3) patients undergoing colostomy/ileostomy during the operation or in the state of colostomy/ileostomy before the operation; (4) patients receiving natural orifice specimen extraction surgery or transvaginal colon surgery; (5) patients with the history of colectomy; (6) emergency operation due to intestinal obstruction, perforation and acute bleeding; (7) intestinal diversion operation; (8) benign lesions confirmed by postoperative pathology; (9) patients not following the colorectal clinical pathway of our department for intestinal preparation and antibiotic application. Univariate analysis and multivariate analysis were used to determine the risk factors of SSI after colon cancer surgery. Results: A total of 1291 patients were enrolled in the study. 94.3% (1217/1291) of cases received laparoscopic surgery. The incidence of overall SSI was 5.3% (69/1291). According to tumor location, the incidence of SSI in the right colon, transverse colon, left colon and sigmoid colon was 8.6% (40/465), 5.2% (11/213), 7.1% (7/98) and 2.1% (11/515) respectively. According to resection range, the incidence of SSI after right hemicolectomy, transverse colectomy, left hemicolectomy and sigmoid colectomy was 8.2% (48/588), 4.5% (2/44), 4.8% (8 /167) and 2.2% (11/492) respectively. Univariate analysis showed that preoperative BUN≥7.14 mmol/L, tumor site, resection range, intestinal anastomotic approach, postoperative diarrhea, anastomotic leakage, postoperative pneumonia, and anastomotic technique were related to SSI (all P<0.05). Multivariate analysis revealed that anastomotic leakage (OR=22.074, 95%CI: 6.172-78.953, P<0.001), pneumonia (OR=4.100, 95%CI: 1.546-10.869, P=0.005), intracorporeal anastomosis (OR=5.288, 95%CI: 2.919-9.577,P<0.001) were independent risk factors of SSI. Subgroup analysis showed that in right hemicolectomy, the incidence of SSI in intracorporeal anastomosis was 19.8% (32/162), which was significantly higher than that in extracorporeal anastomosis (3.8%, 16/426, χ(2)=40.064, P<0.001). In transverse colectomy [5.0% (2/40) vs. 0, χ(2)=0.210, P=1.000], left hemicolectomy [5.4% (8/148) vs. 0, χ(2)=1.079, P=0.599] and sigmoid colectomy [2.1% (10/482) vs. 10.0% (1/10), χ(2)=2.815, P=0.204], no significant differences of SSI incidence were found between intracorporeal anastomosis and extracorporeal anastomosis (all P>0.05). Conclusions: The incidence of SSI increases with the resection range from sigmoid colectomy to right hemicolectomy. Intracorporeal anastomosis and postoperative anastomotic leakage are independent risk factors of SSI. Attentions should be paid to the possibility of postoperative pneumonia and actively effective treatment measures should be carried out.