This score has four categories based on the presence of residual tumor cells and the regression characteristics such as fibrosis, infarct-like necrosis, and acellular mucin: PRGS 1 (complete regression with total absence of tumor cells); PRGS 2 (major regression features with only a few tumor cells i.e. major histological response); PRGS3 (few regression features and predominantly tumor cells i.e. minor histological response); PRGS 4 (absence of response to therapy i.e. absence of any regression feature) [1, 9, 10]. This evidence concerns the gene MUC5AC and neoplasm.