Tumor site, clinicopathological characteristics, and survival of patients undergoing primary elective colorectal cancer resection.

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585 Background: Cancers arising in the proximal and distal colorectum differ in embryological origin, predisposing genetic and epigenetic mutations, clinicopathological characteristics and survival. However, the effect of tumor site on the prognostic value of clinicopathological characteristics and systemic inflammatory responses (SIR) is not known. The present study aims to examine the relationship between tumor site, clinicopathological characteristics and cancer-specific survival (CSS) in patients undergoing elective colorectal cancer (CRC) resection. Methods: Patients who had undergone elective, primary resection of stage I-III CRC (1997-2013) were included. Tumors were categorized as proximal (cecum to splenic flexure) or distal (splenic flexure to rectum) based on pathological reports. SIR was assessed using modified Glasgow Prognostic Score (mGPS; 0-CRP < 10mg/L, 1-CRP > 10mg/L, 2-CRP > 10mg/L and albumin < 35g/L). Results: 796 patients were included; 302 tumors were proximal and 494 were distal to the splenic flexure. Proximal location was associated with advanced age, T stage, poor differentiation, greater lymph node yield, peritoneal involvement and an increased mGPS (all P< 0.01). In all patients, on multivariate survival analysis, distal tumor site, advanced age, T stage, N stage, venous invasion, margin involvement and mGPS were independently associated with reduced CSS (all P< 0.05). In patients with proximal cancer, only age (HR 1.8, P= 0.001), T stage (HR 1.9, P= 0.009), N stage (HR 1.9, P< 0.001) and mGPS (HR 1.6, P= 0.004) were associated with CSS, whereas in patients with distal CRC, T stage (HR 1.4, P= 0.024), N stage (HR 1.5, P= 0.001), venous invasion (HR 1.5, P= 0.038), margin involvement (HR 4.1, P< 0.001) and mGPS (HR 1.5, P= 0.003) were associated with survival. Conclusions: In the present study, tumor site was associated with distinct clinicopathological characteristics. Furthermore, the prognostic value of pathological characteristics currently employed in tumor staging, such as venous invasion and margin involvement, differed with tumor site, whereas evaluation of the SIR was similarly prognostic in patients with proximal and distal CRC.