Outcomes after Definitive Surgery +/- Adjuvant Treatment for Invasive and Non-Invasive FIGO Stage IA Malignant Mixed Müllerian Tumor of the Endometrium

Abstract

Malignant mixed Müllerian tumor (MMMT, also known as carcinosarcoma) is a rare and aggressive subtype of endometrial cancer. Adjuvant treatment after definitive surgery typically involves consideration of chemotherapy and/or radiotherapy, given this histology's high risk for recurrence. In this retrospective study, we sought to characterize the outcomes for patients with early stage MMMT treated within our integrated healthcare system.We queried our institutional cancer database for all cases of endometrial MMMT in the period 2007-2017. Patients age 18 or older who underwent definitive surgery with total hysterectomy and bilateral salpingo-oophorectomy, with or without adjuvant treatment, with AJCC 8th Edition pT1a, FIGO Stage IA disease (all primary disease was confined to the uterus, with less than 50% myometrial invasion) were included for analysis. Patients with synchronous malignancies were excluded from analysis.Of 248 cases of MMMT, 73 met inclusion criteria, with median age at diagnosis of 67 years (range: 24 - 88). Twenty-three of these cases (32%) were non-invasive primary tumors. The median tumor size was 5.0 cm, and 58 (79%) underwent nodal dissection, with median 16.5 regional nodes taken (range: 1 - 55). Lymphovascular invasion was seen in 22 (30%), and of those 8 were described as "focal." Peritoneal washings were done in 31 (42%) cases, all of which were negative for malignant cytology. With respect to adjuvant treatment, 15 (21%) received radiotherapy alone (RT), as either external beam radiotherapy and/or brachytherapy, 12 (16%) received chemotherapy alone, 24 (33%) received both RT and chemotherapy, and 22 (30%) received no adjuvant treatment. Of the 23 non-invasive cases, 7 received RT, 3 received chemotherapy, and 2 received both chemotherapy and RT. Within the median follow-up of 47.4 (range: 4.8 - 153.5) months, there were 20 failures, of which 7 were locoregional, most commonly at the vaginal cuff (4), and 13 were distant, most commonly in the lung (8). There were 21 deaths, 17 of which were attributable to cancer recurrence. Patients with Stage IA non-invasive disease comprised 9 of these failures and 8 deaths.Over a quarter of patients with FIGO Stage IA MMMT in this study experienced recurrence, the majority of whom died of their uterine cancer. Almost half of all recurrences were seen in those without myometrial invasion. A lesser proportion of patients with non-invasive disease received adjuvant treatment compared to their invasive counterparts. These findings suggest patients with Stage IA MMMT may benefit from more aggressive treatment despite their early-stage disease.O. Ikizler: None. H.C. Ko: None.