Three models focused on the classification of the cell types (into four to nine cell types, such as epithelial, inflammatory, fibroblast, and others or adipose, background, debris, lymphocytes, mucus, smooth muscle, normal mucosa, stroma, and cancer epithelium) [20,46,48], while another model focused on the detection of immune cells (CD3+ and CD8+ cells) using the immunohistochemistry (IHC) [47]. The gene discussed is CD8A; the disease is cancer.