Abstract
BACKGROUND: Recent studies have shown an association in non-metastatic colorectal cancer between patient survival and immunoprofiling (expression of CD3, CD4, CD8, CD45, and FOXP3 T cells at the invasive margin (IM) and the tumor center (TC)) regardless of stage. Patients with peritoneal carcinomatosis have a dismal prognosis, but survival can be significantly improved in selected patients who undergo cytoreductive surgery and hyperthermic intraperitoneal chemotherapy (CRS/HIPEC). However, current patient selection for CRS/HIPEC is suboptimal. The purpose of this study is to evaluate immune profiles of patients with peritoneal carcinomatosis and their correlation with overall survival (OS). METHODS: The study cohort included patients from a prospectively maintained database of adults with colorectal peritoneal carcinomatosis who underwent CRS/HIPEC. Immunohistochemistry (IHC) using antibodies to CD3, CD4, CD8, CD45RO, and FOXP3 T cells was performed. IHC image density was calculated using ImageJ software, and an immunoscore was determined. RESULTS: Eighty tumors were evaluated from 66 patients. These included 14 primary sites and 66 metastatic sites. R0/R1 resection was achieved in 44 (66.7%) patients. Known prognostic factors including resection status (HR 1.99, p = 0.004) and lymph node status (HR 3.49, p = 0.002) were associated with overall survival. On multivariate analysis, increased CD3/CD4 IM (HR 0.54, p = 0.03) ratio positively was associated with improved OS. DISCUSSION: This is the first study to assess the utility of subtypes of T cells as prognostic markers in patients with colorectal peritoneal carcinomatosis, which may play a role in patients with low-volume disease. Further studies into immune mechanisms may improve patient selection for cytoreductive surgery and HIPEC as well as provide novel pathways for effective immunotherapy.