Aromatase expression in low-grade endometrial stromal sarcomas: an immunohistochemical study

Abstract

Aromatase expression has been described in stromal cells of endometriosis, adenomyosis and endometrial cancer. We analyzed aromatase expression in a series of 23 low-grade endometrial stromal sarcomas. Archival formalin-fixed and paraffin-embedded material was analyzed with immunohistochemistry. Aromatase expression was evaluated with a monoclonal and a polyclonal antibody using the peroxidase-antiperoxidase method. A score was calculated based on the percentage of positive tumor cells and the staining intensity. Aromatase was seen in 19 (83%) of 23 tumors with monoclonal antibody and 20 (87%) of 23 tumors with polyclonal antibody. Aromatase expression using the monoclonal antibody was scored as high in five (22%), moderate in nine (39%) and low in five (22%) tumors. Four (17%) low-grade endometrial stromal sarcomas did not stain for aromatase. Aromatase expression with the polyclonal antibody was scored as high in seven (31%), moderate in four (17%) and low in nine (39%) tumors. Three (13%) low-grade endometrial stromal sarcomas did not stain for aromatase. Little or no aromatase expression tended to correlate with stage I disease, while higher scores were more frequently associated with advanced disease. Our results demonstrate that most low-grade endometrial stromal sarcomas express aromatase. The staining pattern, however, is heterogeneous. The high percentage of aromatase positivity in low-grade endometrial stromal sarcomas may have implications in the management of these tumors and offer new treatment modalities such as hormonal therapy with aromatase inhibitors.

Hormone Therapy Reduces Recurrence in Stage II-IV Uterine Low-Grade Endometrial Stromal Sarcomas: A Retrospective Cohort Study

“…Reich et al. found a high percentage of aromatase expression positivity in patients with LG-ESS, implying that aromatase inhibitors (e.g., letrozole) may play a role in the treatment of LG-ESS ( 25 ). Another study comparing aromatase inhibitors with progestins for LG-ESS treatment indicated that aromatase inhibitors were superior to progestins because of longer recurrence-free survival and fewer side effects in patients with stage II–IV disease; this, however, is not consistent with our observations ( 5 ).…”

Low-Grade Endometrial Stromal Sarcoma - a Review

“…Most ESS express aromatases [32]. Their expression is associated with tumor growth and may also be relevant to the high recurrence rate [32]. The tumors also sometimes express gonadotrophin-releasing hormone (GnRH) receptors [18].…”

“…Reich et al [31 ]noted high levels of expression of estrogen and progesterone receptors in 71 and 95% of cases, respectively. Most ESS express aromatases [32]. Their expression is associated with tumor growth and may also be relevant to the high recurrence rate [32].…”

Aromatase inhibitor therapy for endometrial stromal sarcoma — two-centre experience

“…Almost 80% of ESS express estrogen (ER) and progesterone receptors (PgR). Moreover, in most cases of ESS, the intratumoral immunohistochemical expression of gonadotropin releasing hormone receptor (GnRH-R) as well as androgen receptor (AR) and aromatase was demonstrated [4,5]. The predictive value of these markers has not been determined to date.…”