CYP19A1 and endometriosis: Although aromatase inhibitors, combined with progestins or GnRH analogs seem to be effective in suppressing pelvic pain associated with endometriosis, their prolonged use in young premenopausal women is limited by the occurrence of major side effects caused by marked systemic hypooestrogenism.19, 20 A way to avoid these side effects would be to specifically inhibit aromatase in the endometriosis lesions delivering those molecules into the endometriosis lesions.21 However, the relevance in the inhibition of the local aromatization is actually unclear.