Although CCL20 exhibits antibacterial activity and may cause autoimmune diseases, such as rheumatoid arthritis, psoriasis, and inflammatory bowel disease, the evidence clearly suggests that the CCL20-CCR6 axis within the TME is strongly associated with cancer, with studies having reported several factors affected by the CCL20-CCR6 axis (Table 1). Here, CCL20 is linked to rheumatoid arthritis.