Assessment of inflammatory infiltrate in colorectal carcinoma with a critical evaluation of the different scoring systems and correlation with prognostic parameters

Abstract

Introduction: The prognostic significance of tumor-infiltrating lymphocytes (TILs) in colorectal cancer (CRC) has been recognized for a long time; yet, there is lack of a standardized scoring system to assess the inflammatory infiltrate which is universally acceptable. We therefore undertook a 1-year retrospective study on CRC to study type of inflammatory reaction in colorectal carcinoma, compare the different scoring systems for tumor immune response, and correlate the local inflammatory response to prognostic parameters.

Materials and methods: A 1-year retrospective study was conducted on archival slides of cases diagnosed with colorectal carcinoma. he inflammatory response was assessed at the invasive margin (IM) as well as within tumor tissue, including stromal inflammatory infiltrate, and quantified using Klintrup-Makinen (K-M) score, Jass score, Crohn's-like reaction, and the International TILs Working Group (ITWG) scoring. The intensity of the inflammatory reaction was correlated with the grade of the tumor, the pT stage, lymph node metastasis, tumor location, and tumor size.

Results: We studied 49 cases of colorectal carcinoma over a period of 1 year with a male-to-female (M:F) ratio of 1.45:1. Proximal colon was the most common site followed by distal colon and rectum. About 77.6% of cases were of low histologic grade, while 22.4% were high-grade tumors. About 18.4% were T1 tumors, 44.9% were T2, 28.6% were T3 tumors, and the remaining 8.2% were T4. In the ITWG system, the TIL response was statistically significant for T stage of the tumor. In the Klintrup-Makinen system, a higher score corresponded with a lower histological grade and this difference was found to be statistically significant. Both the Jass score and Crohn's-like reaction did not show any correlation with the prognostic parameters evaluated in the study. The neutrophil score did not show any significant difference among the prognostic categories. Eosinophils were seen in 43% of cases of CRC, while macrophages were seen in only 2% of cases. Necrosis was absent in 67.3% of cases, focal in 18.4% of cases, moderate in 6.1% of cases, and extensive in 8.2% of cases.

Conclusion: A higher intensity of the inflammatory response correlates with a lower grade/T stage of the tumor. As such, the adoption of a uniform system of reporting the inflammatory response could be of immense benefit in prognostication and treatment of the cases of colorectal carcinoma.

Keywords: Colorectal cancer; inflammatory reaction; scoring.