Towards the introduction of the Immunoscore in the classification of malignant tumors.

The American Joint Committee on Cancer/Union Internationale Contre le Cancer (AJCC/UICC)-TNM staging system provides the most reliable guidelines for the routine prognostication and treatment of colorectal carcinoma. This traditional tumor staging summarizes data on tumor burden (T), the presence of cancer cells in draining and regional lymph nodes (N) and evidence for distant metastases (M). However, it is now recognized that the clinical outcome can significantly vary among patients within the same stage. The current classification provides limited prognostic information, and does not predict response to therapy. Multiple ways to classify cancer and to distinguish different subtypes of colorectal cancer have been proposed, including morphology, cell origin, molecular pathways, mutation status, and gene expression-based stratification. These parameters rely on tumor-cell characteristics. Extensive literature investigated the host-immune response against cancer and demonstrated the prognostic impact of the in situ immune cell infiltrate in tumors. A methodology named "Immunoscore" has been defined to quantify the in situ immune infiltrate. In colorectal cancer, the Immunoscore may add to the significance of the current AJCC/UICC TNM classification since it has been demonstrated to be a prognostic factor superior to the AJCC/UICC TNM-classification. An international consortium has been initiated to validate and promote the Immunoscore in routine clinical settings. The results of this international consortium may result in the implementation of the Immunoscore as a new component for the classification of cancer, designated TNM-I (TNM-Immune).