The impact of postoperative inflammation on recurrence in patients with colorectal cancer.

BACKGROUND: Systemic inflammatory response is strongly linked to among cancer development, progression and poor prognosis. The aim of this study was to clarify the impact of postoperative serum C-reactive protein (CRP) levels on the prognoses of patients with colorectal cancer (CRC). METHODS: A total of 467 patients with stage I-III CRC who underwent curative surgery were retrospectively analyzed. To precisely evaluate the effect of postoperative inflammatory status on prognosis in CRC patients, we excluded patients with postoperative complication or elevated preoperative CRP level (CRP > 1.0 mg/dL). Patients were divided into two groups based on their highest post-resection CRP levels (max CRP): the low CRP group (LCG; < 9.0 mg/dL, n = 385) and high CRP group (HCG; ≥ 9.0 mg/dL, n = 82). Furthermore, the effect of inflammation on malignant potential of CRC cells was evaluated using in vitro peritoneal dissemination model. RESULTS: HCG patients showed significantly worse recurrence-free survival (RFS) than LCG patients (p = 0.012). Multivariate analysis revealed that a higher max CRP was an independent prognostic factor for RFS (HR: 2.07, 95% CI 1.04-3.96, p = 0.038). Concerning the risk factors for high max CRP level, multivariate analysis revealed that older age (p < 0.001), male sex (p < 0.001), higher BMI (p = 0.005), right-sided colorectal cancer (p = 0.008), and longer operative time (p = 0.007) were independent risk factors. A higher max CRP was also significantly associated with peritoneal recurrence (p < 0.001). Additionally, recombinant cytokines enhanced the adhesive ability of CRC cells to mesothelial cell in vitro (p < 0.05). CONCLUSIONS: Postoperative inflammation may be a possible mechanism portending the poor prognosis of CRC patients.