Endometrial stromal sarcoma (formerly termed low-grade ESS or endolymphatic stromal myosis) is distinguished from high-grade ESS or undifferentiated endometrial sarcoma microscopically by a mitotic rate of less than 10 MF/10 HPF and a more protracted clinical course. Recurrences typically occur late, and local recurrence is more common than distant metastases (408–412). Although endometrial stromal sarcoma often behaves in a histologically aggressive fashion, it lacks the aneuploid DNA content and high proliferative index associated with high-grade stromal sarcoma. Flow cytometric analysis can be used to differentiate the two conditions and predict response to therapy.
Endometrial stromal sarcoma extends beyond the uterus in 40% of cases at the time of diagnosis, but the extrauterine spread is confined to the pelvis in two-thirds of the cases. Upper-abdominal, pulmonary, and lymph node metastases are uncommon. Recurrence occurs in almost one-half of cases at an average interval of 5 years after initial therapy. Prolonged survival and cure are common even after the development of recurrent or metastatic disease.
Optimum initial therapy for patients with endometrial stromal sarcoma consists of surgical excision of all grossly detectable tumor. Total abdominal hysterectomy and bilateral salpingo-oophorectomy should be performed. The adnexa should always be removed because of the propensity for tumor extension into the parametria, broad ligaments, and adnexal structures, and the possible estrogen-stimulating effect on the tumor cells if ovaries are retained. A beneficial effect of radiation therapy is reported, and pelvic radiation is recommended for
Table 35.16 Staging for Uterine Sarcomas (Leiomyosarcomas, Endometrial Stromal Sarcomas, Adenosarcomas, and Carcinosarcomas) (2008)
Stage I Tumor limited to uterus IA <5cm IB >5cm
Stage II Tumor extends to the pelvis
IIB Tumor extends to extrauterine pelvic tissue
Stage III Tumor invades abdominal tissues (not just protruding into the abdomen). IIIA One site IIIB > one site IIIC Metastasis to pelvic and/or para-aortic lymph nodes
Stage I Tumor limited to uterus IA Tumor limited to endometrium/endocervix with no myometrial invasion IB Less than or equal to half myometrial invasion IC More than half myometrial invasion
Stage II Tumor extends to the pelvis
IIB Tumor extends to extrauterine pelvic tissue
Stage III Tumor invades abdominal tissues (not just protruding into the abdomen). IIIA One site IIIB > one site IIIC Metastasis to pelvic and/or para-aortic lymph nodes
Carcinosarcomas should be staged as carcinomas of the endometrium.
FIGO Committee on Gynecologic Oncology. FIGO staging for uterine sarcomas. Int J Gynecol Obst 2009;104:179. ∗Note: Simultaneous tumors of the uterine corpus and ovary/pelvis in association with ovarian/pelvic endometriosis should be classified as independent primary tumors.
inadequately excised or locally recurrent pelvic disease (408). There is evidence that endometrial stromal sarcoma is hormone dependent or responsive. Objective responses to progestin therapy were reported in 48% of patients in one series (410). Recurrent or metastatic lesions may be amenable to surgical excision. Long-term survival and apparent cures were noted in patients with pulmonary metastases (413).