International Journal of Radiation Oncology*Biology*Physics
Clinical InvestigationOutcome and Prognostic Factors in Endometrial Stromal Tumors: A Rare Cancer Network Study
Introduction
Sarcomas are a rare form of uterine tumor, accounting for 3–20% of all uterine and <1% of all gynecologic malignancies (1). Endometrial stromal tumors (EST) represent 15% of uterine sarcomas and are the second most common pure mesenchymal tumors of the uterus. According to the classification of Norris and Taylor (2), they have been subdivided for a long time according to mitotic rate into endometrial stromal nodules and low-grade (LG) and high-grade (HG) endometrial stromal sarcomas (ESS). Nevertheless, LG-ESS are composed of cells closely resembling normal proliferative endometrial stromal cells and usually have an indolent course, with an 80–100% 5-year survival (3), whereas HG-ESS are known to be more aggressive, with a poor outcome due to a high tendency for distant spread, similar to other uterine sarcomas such as leiomyosarcomas. High-grade ESS have more than 10 mitoses per 10 high-power fields, in addition to marked cytologic atypia, a diffuse infiltration into the myometrium, a lack of plexiform vasculature, and a predominant endometrial stromal differentiation. Therefore, several pathologists have suggested replacing the term “HG-ESS” with “undifferentiated or poorly differentiated ESS” (UES). Today the term “endometrial stromal sarcoma” should refer only to LG-ESS (4). Standard treatment for ESS consists of hysterectomy with bilateral salpingo-oophorectomy (BSO). The current options for adjuvant treatment include radiotherapy (RT), chemotherapy (CT), and hormonal therapy. However, the optimal adjuvant management remains unclear (5). The fact that EST were mostly considered as the same entity in the few reported series adds to the confusion. Furthermore, there is no consensus regarding prognostic factors. These sarcomas therefore represent a challenging group of tumors to manage.
The aim of this study was to provide further understanding of EST and to assess the rates, time, and sites of recurrences for patients with ESS and UES according to stage and treatment, and to identify prognostic factors.
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Methods and Materials
This was a retrospective multicenter study in the framework of the Rare Cancer Network. Data from 66 patients with EST treated between 1987 and 2007 in 11 institutions were collected. Inclusion criteria were patients who underwent comprehensive surgery, including hysterectomy with or without BSO. Adjuvant treatment modalities consisted of observation after surgery, vaginal brachytherapy (BT), external-beam radiotherapy (EBRT), and/or CT. The choice of adjuvant therapy was based on physician and
Patient demographics
Data from 66 patients were collected. Of these, 7 cases were ineligible owing to incomplete data or unclear histology. A total of 59 patients met the study requirements. The median age at diagnosis was 53.7 years (range, 31.0–82.0 years) and was significantly different between the two groups: 51.0 and 59.3 years for ESS and UES, respectively (p < 0.05). Nine patients (15.2%) were premenopausal at diagnosis, 66% postmenopausal, and the other women perimenauposal. The most common symptom was
Discussion
The majority of our patients received either BT or EBRT. We found a positive impact of adjuvant RT on OS and DFS. This finding, however, should be taken with caution because of the substantial study period, more than 20 years, and the low statistical power given the size of the cohort. Nonetheless, our study reports one of the best 5-year OS rates reported in the literature to date. The European Organization for Research and Treatment of Cancer 55874 randomized trial, including all uterine
Conclusion
The prognosis of ESS varies significantly from that of UES. As a result they need to be considered as two different entities. The 5-year OS of ESS was excellent, although half of the patients had a relapse, most frequently in the pelvis. Therefore, adjuvant treatment such as RT should be considered even in low-grade tumors. Multicenter randomized studies are still warranted to establish clear guidelines in the management of EST.
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Conflict of interest: none.