Relationship between body mass index and short-term postoperative prognosis in patients undergoing colorectal cancer surgery

BACKGROUND: Obesity is a state in which excess heat is converted into excess fat, which accumulates in the body and may cause damage to multiple organs of the circulatory, endocrine, and digestive systems. Studies have shown that the accumulation of abdominal fat and mesenteric fat hypertrophy in patients with obesity makes laparoscopic surgery highly difficult, which is not conducive to operation and affects patient prognosis. However, there is still controversy regarding these conclusions. AIM: To explore the relationship between body mass index (BMI) and short-term prognosis after surgery for colorectal cancer. METHODS: PubMed, Embase, Ovid, Web of Science, CNKI, and China Biology Medicine Disc databases were searched to obtain relevant articles on this topic. After the articles were screened according to the inclusion and exclusion criteria and the risk of literature bias was assessed using the Newcastle-Ottawa Scale, the prognostic indicators were combined and analyzed. RESULTS: A total of 16 articles were included for quantitative analysis, and 15588 patients undergoing colorectal cancer surgery were included in the study, including 3775 patients with obesity and 11813 patients without obesity. Among them, 12 articles used BMI ≥ 30 kg/m(2) and 4 articles used BMI ≥ 25 kg/m(2) for the definition of obesity. Four patients underwent robotic colorectal surgery, whereas 12 underwent conventional laparoscopic colorectal resection. The quality of the literature was good. Meta-combined analysis showed that the overall complication rate of patients with obesity after surgery was higher than that of patients without obesity [OR = 1.35, 95%CI: 1.23-1.48, Z = 6.25, P < 0.0001]. The incidence of anastomotic leak after surgery in patients with obesity was not significantly different from that in patients without obesity [OR = 0.99, 95%CI: 0.70-1.41), Z = -0.06, P = 0.956]. The incidence of surgical site infection (SSI) after surgery in patients with obesity was higher than that in patients without obesity [OR = 1.43, 95%CI: 1.16-1.78, Z = 3.31, P < 0.001]. The incidence of reoperation in patients with obesity after surgery was higher than that in patients without obesity; however, the difference was not statistically significant [OR = 1.15, 95%CI: 0.92-1.45, Z = 1.23, P = 0.23]; Patients with obesity had lower mortality after surgery than patients without obesity; however, the difference was not statistically significant [OR = 0.61, 95%CI: 0.35-1.06, Z = -1.75, P = 0.08]. Subgroup analysis revealed that the geographical location of the institute was one of the sources of heterogeneity. Robot-assisted surgery was not significantly different from traditional laparoscopic resection in terms of the incidence of complications. CONCLUSION: Obesity increases the overall complication and SSI rates of patients undergoing colorectal cancer surgery but has no influence on the incidence of anastomotic leak, reoperation rate, and short-term mortality rate.