Benign metastasizing leiomyoma (BML): A retrospective case series analysis of 8 patients (pts).

e22525 Background: BML is a rare entity marked by the presence of lung lesions in women with a history of surgery for a benign leiomyoma of the uterus. Optimal treatment strategy for BML is poorly defined. We report on the activity of systemic therapy in a retrospective series of pts with BML. Methods: Cases diagnosed with BML from June 1993 to January 2017 at Istituto Nazionale Tumori, Milan, were reviewed. Results: Eight pts were identified, with a median age of 43 yrs. Estrogen and progesteron receptors were positive in all cases. All pts underwent surgery (3 hysterectomy, 2 myomectomy, 2 hysteroannessiectomy and 1 left ovariectomy) for suspected uterine leiomyoma (1 leg; 1 thigh); 2 pts had concomitant lung disease. 8 pts developed lung metastases and 2 had also limb metastases. 2 pts underwent lung metastasectomy, followed by watchful waiting with CT every 6 mos and were disease-free at their last follow up after 132 mos and 84 mos from diagnosis. 6 pts received systemic therapy for progressing advanced disease (1-6 lines). Among 6 pts treated, 2 were in fertility age and underwent ovary-sparing hysterectomy, receiving GnRH agonist with 1 PR lasting 96 mos and 1 SD lasting 38 mos; 2 pts received an aromatase inhibitor with 1 PR lasting 24 mos and 1 SD lasting 12 mos; 2 pts received oral estrogens with 1 PR lasting 39 mos and 1 SD lasting 2 mos; 1 pt received oral progestins with a PR lasting 12 mos; 3 patients received antracyclin +/- ifosfamide obtaining 2 PR after 3 cycles (cys) and 1 SD after 3 cys lasting 6 mos; 1 pt received high-dose ifosfamide with a PR after 5 cys; 1 pt received ifosfamide+dacarbazine obtaining a CR after 6 cys; 2 pts received gemcitabine with 1 PR after 3 cys and 1 SD after 2 cys lasting 6 mos; 1 pt received oral etoposide with a PR lasting 21 mos; 1 pt received sorafenib with a SD lasting 6 mos; 1 pt received everolimus with a PR lasting 57 mos. In this case, everolimus was discontinued due to lung toxicity. No pts progressed during treatment. At a median follow-up of 55 mos, 6 pts are alive, while 2 are dead of disease. Conclusions: In a series of 8 pts, we confirm the activity of hormonal treatment in BML. mTOR inihibitors or chemotherapy also show to be active.