Objective To analyze the impact of preoperative pulmonary dysfunction on postoperative complications in patients with rectal cancer. MethodsPatient information was extracted from the updated version of West China Database from Colorectal Cancer in April 2024. The incidences of preoperative pulmonary dysfunction and postoperative complications were analyzed. Multivariate logistic regression analyses were employed to explore the risk factors for complications occurring in postoperative phases (in-hospital, short-term). ResultsA total of 1 726 patients with rectal cancer were included. Among them, 684 (39.6%) had preoperative pulmonary dysfunction, while 1 042 (60.4%) did not. Compared to patients without preoperative pulmonary dysfunction, those with pulmonary dysfunction were older [(65.04±10.19) years vs. (57.09±11.83) years, P<0.001], had higher proportion of males [62.9% (430/684) vs. 55.7% (580/1 042), P=0.003], smaller tumor distance from the anal verge [5.0 (1.7, 8.0) vs. 5.0 (2.0, 10.0) cm, P=0.004], higher rates of diabetes [29.8% (204/684) vs. 22.0% (229/1 042), P<0.001] and hypertension [49.0% (335/684) vs. 39.0% (406/1 042), P<0.001]. There were no statistically significant differences in the overall incidence of complications between the two groups during the in-hospital [7.5% (51/684) vs. 7.7% (81/1 042), P=0.798], short-term [6.3% (43/684) vs. 5.5% (57/1 042), P=0.472] and long-term [0.3% (2/684) vs. 0.4% (4/1 042), P=0.552]. However, spectrum analysis showed that the pulmonary dysfunction group had a lower incidence of in-hospital non-digestive system complications [37.3% (19/51) vs. 65.4% (53/81), P=0.019] and a higher incidence of short-term other digestive system complications [20.9% (9/43) vs. 7.0% (4/57), P=0.028]. After controlling for demographic, comorbidity, and tumor-related factors, multivariate logistic regression analysis revealed that preoperative pulmonary dysfunction was not a risk factor of in-hospital complications [OR=0.832, 95%CI (0.559, 1.237), P=0.363] and short-term complications [OR=1.106, 95%CI (0.708, 1.728), P=0.658].ConclusionsPatients with rectal cancer have a relatively high incidence of preoperative pulmonary dysfunction, but it shows no statistically significant association with in-hospital or short-term postoperative complications. Instead, its impact is reflected in changes to the spectrum of complications.