Postoperative dynamics of inflammatory markers in patients with uncomplicated recovery after colorectal cancer surgery: a preliminary inflammatory benchmarks study

Colorectal cancer (CRC) remains a leading cause of cancer-related morbidity and mortality worldwide, with surgical resection as the cornerstone of curative therapy for localized disease. Surgery triggers a profound systemic inflammatory response that influences recovery, complications, and oncologic outcomes. While elevated NLR, PLR, and SII pre- or postoperatively predict adverse events like anastomotic leakage and poor survival, their normal temporal trajectories in uncomplicated cases remain poorly defined, hindering clinical interpretation. This preliminary study was conducted at two tertiary centers, screening 88 consecutive adults (≥ 18 years) undergoing elective curative (R0) CRC resection (stages I-III, open/laparoscopic). Inclusion required Clavien-Dindo grade ≤ I recovery (no intervention beyond symptomatic treatment; ERAS discharge criteria met) and complete blood counts (preop baseline ≤ 7 days, POD1/15/30). Exclusions: emergencies, immunosuppression, severe comorbidities (e.g., eGFR < 30, HbA1c > 10), neoadjuvant < 4 weeks prior, grade ≥ II complications (e.g., leak, sepsis, readmission). Only the uncomplicated cohort (n = 47; median age 50 years; 62% female) was finally analyzed. EDTA-blood analyzed via automated hematology (neutrophils/lymphocytes/platelets); markers calculated; trajectories via Friedman test; 5th-95th percentile intervals. All markers declined significantly (P < 0.001). NLR medians: POD1 12.5 (IQR 5.6-26.1), POD15 3.4 (2.5-6.4), POD30 2.6 (1.7-5.1); 95th percentiles 49.0 to 11.9. PLR: POD1 366.1 (223-682), POD15 244.9 (173-330), POD30 194.5 (129-319); 95th 1455 to 658.5. SII: POD1 3520 (1473-8806), POD15 1244 (757-2223), POD30 789 (470-1389); 95th 17,063 to 3311. Neutrophils fell (8.99 to 4.4 × 10^9/L), lymphocytes rose (0.71 to 1.25 × 10^9/L). Uncomplicated CRC resection recovery features rapid normalization of NLR, PLR, and SII over 30 days, providing preliminary time-specific percentile-based benchmarks for describing expected postoperative inflammatory trajectories. These findings should be interpreted as exploratory and require validation in larger multicenter cohorts before clinical application.