Expression of oestrogen and progesterone receptors in low-grade endometrial stromal sarcomas

We analysed oestrogen receptor (ER) and progesterone receptor (PR) expressi on in a retrospective series of 21 low-grade endometrial stromal sarcomas ( LGSSs). Archival formalin-fixed and paraffin-embedded material was analysed by immunohistochemistry. ER and PR were measured with monoclonal antibodie s and the peroxidase-antiperoxidase method and a score was calculated as fo r breast carcinoma based on both the percentage of positive tumour cell nuc lei and the staining intensity. ER were seen in 15 (71%) and PR in 20 (95%) of tumours respectively. ER expression was scored as high in three (14%), moderate in four (19%), and low in eight (38%) tumours. Six (29%) tumours d id not stain for ER and all of these were positive for PR. PR expression wa s scored as high in eight (38%), moderate in ten (47%) and weak in two (10% ) LGSSs. Only one (5%) LGSS did not stain for PR (this tumour was positive for ER). ER and PR expression in LGSS is heterogeneous. This may have impli cations for hormone therapy in the management of these tumours. These resul ts suggest that ER and PR should be routinely quantified in LGSSs by immuno histochemical methods. (C) 2000 Cancer Research Campaign.