ObjectiveTo analyze the impact of preoperative hypoproteinemia on postoperative complications in patients with rectal cancer based on the current version of the Database from Colorectal Cancer (DACCA). MethodsThe patient information was extracted from the updated version of DACCA in April 2024 according to predefined inclusion criteria. The preoperative hypoproteinemia and incidence of complications were analyzed. The univariate and multivariate logistic regression analyses were performed to identify risk factors for complications in three postoperative periods (in-hospital, short-term, and long-term). The test level was α=0.05. ResultsA total of 1 440 patients with rectal cancer were included, 322 (22.4%) with preoperative hypoproteinemia and 1 118 (77.6%) without. Compared to the patients without preoperative hypoproteinemia, those with preoperative hypoproteinemia were older (P<0.001), had a lower body mass index (P<0.001), smaller tumor margins (P<0.05), and a higher proportion of patients with pTNM stage Ⅲ or Ⅳ (P<0.001). There were no statistically significant differences in the overall incidence of complications during the three postoperative periods (in-hospital, short-term, and long-term) between the patients with and without preoperative hypoproteinemia (χ2=0.399, P=0.280; χ2=0.298, P=0.585; χ2=1.416, P=0.234). Except for urinary retention, there were no significant differences in the incidence of specific complications between the two groups (P>0.05). The univariate and multivariate logistic regression analyses did not identify preoperative hypoproteinemia as a risk factor for postoperative complications (P>0.05). ConclusionsThe results of this study suggest that the incidence of preoperative hypoproteinemia is higher in patients with rectal cancer. Patients with preoperative hypoproteinemia tend to be older, have a lower body mass index, and a higher proportion of pTNM stage Ⅲ or Ⅳ. However, it was not found that preoperative hypoproteinemia is a risk factor for postoperative complications.