For pelvic pain associated with endometriosis, COCPs are considered a first-line medical treatment, along with NSAIDs, GnRH agonists, and aromatase inhibitors. COCPs work to suppress the growth of the extra-uterine endometrial tissue. This works to lessen its inflammatory effects. COCPs, along with the other medical treatments listed above, do not eliminate the extra-uterine tissue growth, they just reduce the symptoms. Surgery is the only definitive treatment. Studies looking at rates of pelvic pain reoccurrence after surgery have shown that continuous use of COCPs is more effective at reducing the recurrence of pain than cyclic use.