Endometriosis and the Hallmarks of Cancer

Endometriosis (EMS) is a non-cancerous invasive condition where tissue resembling the lining of the uterus is found outside of the uterine cavity. Endometriotic lesions have been found in nearly every organ of the body. This review highlights examples of EMS exhibiting all eight established hallmarks of cancer: hyperproliferation (e.g. through estrogen signalling), evasion of growth suppression (e.g. through progesterone resistance), immunosurveillance evasion (e.g. through reduction of natural killer cell cytotoxicity), enabling replicative immortality (e.g. through increased telomere length), invasion (e.g. through epithelial-to-mesenchymal transition), induction of angiogenesis (e.g. through upregulation of hypoxia-inducible factors), resistance to apoptosis (e.g. through increased expression of survivin), and deregulation of cellular metabolism (e.g. through increased production of lactate). Therefore, despite being considered a non-cancerous, benign condition, EMS is highly cancer-like in its behaviours to promote invasion and ectopic survival. The presence of all hallmarks of cancer amongst endometriotic behaviours highlights that to expand understanding of endometriotic metastasis, as well as potential modes for management of EMS, it may be possible to leverage the larger knowledge base associated with cancer.