Further image discrimination between M1- and M2-type macrophages using the other cellular markers including CD80 (M1 marker) was not successful; nevertheless, these observations suggested that macrophages were relatively skewed towards M2 in the peritoneal cavity with positive cytology, and pancreatic cancer cells exfoliated from a primary lesion would encounter such macrophages as tumor-associated macrophages (TAMs) in the environment of the peritoneal cavity. Here, CD80 is linked to pancreatic neoplasm.