Chapter 7: Uterine Sarcomas

INTRODUCTION

Sarcomas comprise approximately 3% to 7% of uterine corpus malignancies. Although they represent a small proportion of uterine cancers, they disproportionately contribute to mortality. Their biologic behaviors are highly variable, ranging from a locally invasive process with minimal metastatic risk to highly aggressive tumors that are characterized by intra-abdominal or disseminated hematogenous spread. This reflects the complex origin of the malignant tissue components: endometrium, endometrial stroma, and smooth muscle, plus supportive elements of the uterine corpus.

EPIDEMIOLOGY

Key Points

1. Uterine sarcomas represent only 3% to 7% of all uterine malignancies.

2. The median age for patients with uterine sarcomas is 57 years, but patients with carcinosarcoma are approximately 10 years older.

3. African American women have a higher incidence of both leiomyosarcomas and carcinosarcomas.

4. Carcinosarcomas have been associated with a history of previous pelvic radiation and previous tamoxifen use.

Using Surveillance, Epidemiology, and End Results (SEER) data from the National Cancer Institute from 1988 to 2001, there were 48,642 uterine malignancies, of which 3742 were uterine sarcomas (7.7%).¹ The relative proportions of the 4 major uterine sarcoma categories are noted in Table 7-1.² Carcinosarcomas are now considered to be an aggressive, dedifferentiated, or metaplastic form of endometrial cancer, and some authors therefore exclude them from the uterine sarcoma classification list.³ However, the vast majority of previous clinical studies have included carcinosarcomas with other uterine sarcomas, and that convention is followed in this chapter. The World Health Organization (WHO) classification scheme for uterine sarcomas is noted in Table 7-2,⁴ and uterine sarcomas are divided into 2 large pathologic categories: mesenchymal and mixed epithelial and mesenchymal tumors. Table 7-2 includes common and uncommon variants, as well as benign tumors (eg, leiomyomas, adenofibromas), malignant tumors (eg, leiomyosarcomas, carcinosarcomas), and those of uncertain malignant behavior (eg, smooth muscle tumor of uncertain malignant potential [STUMP]).