Simple Postoperative Markers for Early Identification of Low-Risk Patients After Gastric or Colorectal Cancer Surgery: A Retrospective Cohort Study

BackgroundEarly identification of low-risk patients after curative gastric or colorectal surgery can enable safe, timely discharge. We evaluated two routinely available postoperative markers-serum prealbumin (PA) and lymphocyte percentage (L%)-as a simple rule-out strategy.MethodsThis is a single-center retrospective cohort study with a temporal external validation set. Prealbumin (mg/dL) and L% (%) were measured on postoperative day (POD)1/3/5. We prespecified a high-sensitivity threshold (sensitivity ≥90%) in the training cohort and assessed its performance in the validation cohort. Multivariable logistic models were fitted at POD3 and POD5.ResultsPostoperative day 1 L% showed limited discrimination; analyses focused on POD3/5. At both time points, PA and L% were independent protective predictors, with no effect modification by tumor site. Slim (PA + L%) and Full models had similar discrimination; both were well calibrated, and decision-curve analysis indicated clear net benefit over default strategies. Under the fixed high-sensitivity approach, the POD3 Slim model maintained high sensitivity and NPV with moderate specificity.ConclusionsBy POD3, combining PA and L% provides a low-cost, readily deployable, rule-out-oriented approach that supports safe early discharge within structured postoperative pathways. Multicenter prospective validation and impact studies are warranted.