The host inflammatory responses, tumor stroma percentage, and survival in colorectal cancer.

Abstract

549 Background: The role of host inflammatory responses in determining colorectal cancer (CRC) outcome is increasingly recognised. In particular, a marked local inflammatory response is associated with improved survival. However, determinants of this response are not clear. A plausible factor in the density, location and type of the inflammatory cell infiltrate is the extent of tumor stroma. The aim of the present study was to examine the relationship between tumor stroma percentage (TSP), tumor inflammatory infiltrate and survival in patients undergoing elective CRC resection. Methods: 335 patients who had undergone elective resection for stage I-III CRC at a single institution between 1997-2008 were included. TSP at the invasive margin (IM) was assessed on H and E sections and grouped as low (≤50%) or high (>50%). Local inflammatory response was assessed at the IM using Klintrup-Mäkinen (K-M) score and at the IM, tumor stroma and cancer cell nests (CCNs) using the following T-cell markers: CD3, CD8, CD45R0, FOXP3. Systemic inflammatory response was assessed using modified Glasgow Prognostic Score (mGPS). Results: Eighty-three patients (25%) had high TSP. High TSP was associated with increased T stage, N stage (both p < 0.01), margin and serosal involvement (both p < 0.05), an infiltrative invasive margin (p < 0.001) and tumor necrosis (p = 0.001). TSP was associated with decreased infiltration by CD3+ and CD8+ cells at the CCNs (p < 0.01 and p < 0.05 respectively) but not at the IM or stroma. K-M score showed a trend towards an inverse association with TSP (p = 0.067). CD45R0+ and FOXP3+cell infiltration and mGPS were not associated with TSP. On multivariate analysis, TSP was associated with poorer cancer-specific survival (HR 1.93, 95% CI 1.15-3.23, p = 0.012), independent of N stage, VI (both p < 0.05), low CD8 at the IM and CCNs (both p < 0.01) and mGPS (p = 0.001). Conclusions: TSP was associated with the presence of high risk pathological characteristics and down-regulation of host intra-tumoral immune responses and was independently associated with poorer cancer survival. The extent of tumor stroma is an important factor in the nature of the tumor inflammatory cell infiltrate and outcome in patients undergoing elective surgery for CRC.