The obtained results can be explained by an increase (in the peritoneal fluid of extragenital endometriosis patients) in the number of cytokines activating angiogenesis, such as IL-1β, IL-6, and IL-8 [40], and stimulating the adhesion of endometrial cells to the peritoneal mesothelium TNFα [41], as well as vascular endothelial growth factors (VEGFs) [42], which enhance the invasive properties of cells in culture. This evidence concerns the gene IL1B and endometriosis.