Stage IA vs. IB endometrial stromal sarcoma: Does the new staging system predict survival?

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Abstract

Objective

To determine the correlation of the new FIGO staging system with survival in stage I patients with low-grade and high-grade endometrial stromal sarcomas.

Methods

Data were extracted from the Surveillance, Epidemiology, and End Results database between 1988 and 2005. Kaplan–Meier log rank and Cox proportional hazards models were used for survival analysis and to identify possible predictors for survival.

Results

The identified cohort included 464 women, 310 (67%) low-grade endometrial stromal sarcoma, 96 (21%) high-grade endometrial stromal sarcoma, and 58 (12%) unclassified endometrial stromal sarcoma. Among low-grade and high-grade endometrial stromal sarcomas, there was no significant demographic or clinico-pathologic difference between stages IA and IB. The 5-year overall survival was worse in high-grade endometrial stromal sarcoma than low-grade endometrial stromal sarcoma (45.4% vs. 97.2%, p < 0.001). The difference in 5-year overall survival among women with low-grade endometrial stromal sarcoma between stages IA and IB was significant (100% vs. 93.5%, p = 0.003), but not among women with high-grade endometrial stromal sarcoma (51.4% vs. 43.5%, p = 0.27). Although age (p = 0.001), race (p = 0.005), and stage (p = 0.004) were all significant prognostic factors in low-grade endometrial stromal sarcoma, only cervical involvement (p = 0.02) was a significant predictor in high-grade endometrial stromal sarcoma.

Conclusion

The new staging system is appropriate for risk stratification in low-grade endometrial stromal sarcoma. The prognosis in high-grade endometrial stromal sarcoma seems to be most influenced by the presence of cervical involvement and not by tumor size as the staging criteria would suggest.

Introduction

Endometrial stromal sarcoma is a rare neoplasm. According to an analysis of the Surveillance, Epidemiology, and End Results (SEER) program data, the overall incidence of uterine endometrial stromal sarcoma is 1.8 per million [1]. Endometrial stromal sarcoma histologically resembles stromal cells found during the proliferative phase of the menstrual cycle and displays a characteristic pattern of myometrial infiltration and a rich network of small arterioles resembling the spiral arterioles of the secretory endometrium [2]. It has traditionally been classified on the basis of nuclear size, degree of atypia, and mitotic index into either a low-grade endometrial stromal sarcoma or a high-grade endometrial stromal sarcoma [3]. However, tumors in the latter category (displaying more than 10 mitotic figures per 10 high power fields, and/or grade 2 or 3 nuclear atypia) have been suggested to be classified as endometrial sarcomas or undifferentiated sarcomas, given their lack of neoplastic cells with endometrial stromal cell differentiation[4], [5].

It is well known that prognosis is poor for high-grade endometrial stromal sarcoma. Multiple reports in the literature have confirmed that low-grade and high-grade endometrial stromal sarcomas have a completely different biological aggressiveness and clinical behavior [6], [7], [8], [9], [10]. Furthermore, most reports have failed to show any significant differences between high-grade endometrial stromal sarcoma and other high-grade uterine sarcomas such as leiomyosarcoma [6], [11]. Therefore, it is widely agreed upon that low-grade and high-grade endometrial stromal sarcomas are distinct entities (both morphologically and functionally), and have been regarded as such in this report.

Tumor size has been shown to be of prognostic significance in endometrial stromal sarcoma in various studies [6], [7]. Until recently, the 1988 FIGO surgical staging system for endometrial cancer was recommended for staging endometrial stromal sarcoma. In 2008 a revised, new FIGO staging system was introduced for endometrial stromal sarcoma, classifying endometrial stromal sarcoma with the more common leiomyosarcoma[12]. In the 2008 FIGO staging system; stages I and II of the 1988 FIGO staging system of endometrial cancer have been combined to represent stage I endometrial stromal sarcoma. Additionally, the new FIGO staging system for endometrial stromal sarcoma replaced the stage defining factors from the 1988 FIGO staging system of myometrial invasion and cervical involvement with a single variable, tumor size.

Our objective was to determine the correlation of the new staging system with survival in patients with stage I low-grade and high-grade endometrial stromal sarcomas. Specifically, we evaluated the validity of employing tumor size as a staging variable preferentially over the variables used in the past, i.e. myometrial invasion and cervical involvement. We also determined whether tumor size, by itself, accounts for a survival difference between stages IA and IB. This information may be particularly valuable since the majority of patients (about 80%), particularly those with low-grade endometrial stromal sarcoma, are diagnosed when the disease is still limited to the uterus [13].

Section snippets

Materials and methods

Demographic, clinicopathologic, and survival information for women diagnosed with endometrial stromal sarcoma [International Classification of Diseases code (ICD)-O-3 topography: C 55.9 (uterus, NOS), and morphology: 8930 (endometrial stromal sarcoma NOS), and 8931 (low-grade endometrial stromal sarcoma)] from January 1, 1988, to December 31, 2005, were extracted from the Surveillance, Epidemiology and End Results (SEER) database of the U.S. National Cancer Institute [14]. This is a population

Results

From 1988 to 2005, a total of 464 patients that met eligibility criteria were identified. The cohort included 310 (67%) patients with low-grade endometrial stromal sarcoma, 96 (21%) patients with high-grade endometrial stromal sarcoma, and in 58 (12%) patients grade was not specified. The clinical and demographic characteristics of the cohort are displayed in Table 1. Low-grade endometrial stromal sarcoma patients were younger than those with high-grade endometrial stromal sarcoma; mean age at

Discussion

Optimal management of cancer requires consideration of the extent of disease spread. The objective of cancer staging is to reliably and accurately group patients experiencing similar outcomes into prognostic categories [15]. Cancer staging plays a pivotal role in treatment planning as well as in communicating the patient's unique prognostic risk category. A general staging schema for most malignancies includes; stage I when disease is confined to the organ of origin, stage II when disease

Conflict of interest statement

The authors have no conflict of interest to declare.

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