PAX8 and breast carcinoma: WT-1 is mainly expressed in ovarian cancer, and less than 10% of primary breast cancers are positive for WT-1, which are usually weakly expressed or focally expressed.[7,9,42] PAX8 is a pivotal transcription factor in ovary and regulates the expression of WT-1, which is admitted with higher sensitivity and specificity than WT-1.