PGR and ovarian cancer: In a more recent robust study investigating hormone-receptor expression and ovarian cancer survival in 2933 patients, the proportion of tumors that stained positive for PR was highest for endometrioid type (67.4%) and low-grade serous type (57.4%), followed by HGSC (31.1%), and lowest for mucinous type (16.4%) and clear cell type (8.0%) [14].