The Study: This report validates the prognostic value of the Immunoscore for stage I-III colon cancer. Here’s how it works. CD3 and CD8 immunohistochemistry (IHC) is performed on sections of tumor that include its invasive margin. Digital image analysis is then used to determine the density of CD3 and CD8 T-cells (i.e. tumor infiltrating lymphocytes) in the tumor. A low score is 0-25% density, and a high score is 70-100%. Of the >2600 tumors sampled, roughly 50% had an intermediate score and about 25% had each low and high scores. Five year recurrence rates separated out nicely to 10, 20, and 30% for high, intermediate, and low Immunoscores, respectively. In addition, Immunoscore was associated with overall survival independent of other clinical prognostic factors. To no real surprise, MSI-high tumors had higher rates of high (favorable) Immunoscores. Yes, the above approach is a rather rudimentary way to look at tumor immune infiltrate (see below), but the methods at their core can easily be updated to accommodate whatever becomes to next IHC marker du jour.
Bottom Line: The Immunoscore is the first large-scale, standardized method to mass profile tumor-host immune interaction in solid tumors. | Pages, Lancet 2018