The OR1 2025 project conducted and led by dr Nicola Sarandria focused on a quantitative analysis of tumor-associated neutrophils (TANs) on formalin embedded sections of rectal cancer using CD66b and ARG1 immunohistochemical staining. In this book results of the OR1 study are discussed, focusing on new insights on Arginase-1, TANs and Perineural invasion in Rectal cancer. This discussion is combined with stimulating sections regarding the theoretical background of the project.