Association between preoperative respiratory function and postoperative complications in patients with colorectal cancer: a retrospective study

Postoperative pulmonary complications (PPCs) in patients with colorectal cancer worsen long-term survival, making preoperative prediction and prevention critically important. However, the association between the preoperative respiratory function and PPCs in colorectal cancer surgery remains unclear. This study aimed to clarify this association. This retrospective study included patients who underwent colorectal cancer surgery and preoperative respiratory tests at Kanazawa University Hospital between November 2006 and May 2025. Low respiratory function was defined as a forced expiratory volume in one second/forced vital capacity ratio (FEV 1 /FVC) < 70%. The primary outcome was PPC incidence, including pneumonia and atelectasis. Propensity score matching, exact within 5-year blocks of the year of surgery, was used to adjust for patient background, and logistic regression, including Firth’s penalized likelihood method, was used to identify factors associated with PPCs. Of the 1164 patients, 839 (72.1%) had normal and 325 (27.9%) had low respiratory function. After matching, 167 patients were included in each group, with no significant difference in PPC incidence (1.8% vs. 1.2%, P = 1.000). In a multivariate analysis, low respiratory function was not a significant risk factor for PPCs (odds ratio: 1.070, 95% confidence interval: 0.448–2.540). Preoperative respiratory function was not identified as an independent risk factor for PPCs after colorectal cancer surgery, although the study was underpowered to exclude a moderate association. Large-scale multicenter studies are required.