Validation of the Glasgow Microenvironment Score in patients with colon cancer: A pathology-based prognostic tool.

Abstract

206 Background: The Glasgow Microenvironment Score (GMS), comprised of assessment of the tumour inflammatory cell infiltrate (using Klintrup-Mäkinen (KM) grade) and tumour-associated stroma (TSP), has been reported as a stage-independent prognostic score in patients with colorectal cancer. The present study aims to validate the GMS and examines its prognostic utility in the context of stage and MMR status. Methods: Patients who had undergone resection of stage I-III colon cancer were included ( n= 495). GMS was scored by combining KM and TSP as follows: high KM scores 0; low KM with low TSP scores 1; low KM and high TSP scores 2. Cancer specific (CSS) and overall survival (OS) were primary endpoints. Subgroup analysis was performed to assess the utility of GMS according to TNM, venous invasion and MMR status. Results: There were 30% of patients with GMS 0, 56% with GMS 1 and 14% with GMS 2. Five-year survival for GMS 0, 1 and 2 across the whole cohort were 89%, 74% and 66%, respectively. GMS was associated with age, mode of presentation, TNM, venous invasion and MMR status. On multivariate analysis, GMS was independently associated with CSS (HR 1.35, 95% CI: 1.02-1.79, p= 0.04) and OS (HR 1.23, 95% CI: 1.02-1.48, p= 0.03); this was independent of emergency presentation ( p< 0.01), T-stage ( p= 0.03) and N-stage ( p< 0.001) for CSS. Subgroup analysis found that GMS was able to stratify CSS regardless of node-negative or node-positive disease (both p< 0.01), venous invasion ( p< 0.05), elective presentation ( p< 0.01) and MMR-proficient tumours ( p< 0.001), although it was not able to stratify emergency presentation ( n= 154) or MMR-deficient disease ( n= 102) due to small sample size. Universally, the prognosis for GMS 0 was good, but was poor for GMS 2. The prognosis for GMS 1 varied depending on MMR and nodal status. Conclusions: This study validates the use of the GMS as an independent prognostic pathology-based tool for stratification of colon cancer. It could be readily applied to routine clinical practice and may be used to aid decision making regarding adjuvant treatments in colorectal cancer. It should be further validated in prospective randomised trials.