The combination of C3a/C3aR and C5a/C5aR has various biological effects, which can regulate the proliferation and function of various cells in the human body, such as T cells, eosinophils/basophils, mast cells, etc. It also plays an important role in various inflammatory diseases and even tumor progression and metastasis [28, 29]. Here, C5AR1 is linked to neoplasm.