Background: Female breast cancer (BC) has become the most diagnosed cancer and the fifth leading cause of cancer mortality worldwide. Metastatic breast cancer is a main differential diagnosis for any suspected metastatic carcinoma in women due to its high incidence. It's essential to identify a sensitive and specific marker to diagnose primary breast cancer. TRPS1 is a novel nuclear transcription factor, belonging to the GATA family with a transcriptional repressor function. This study aimed to assess the diagnostic value of TRPS1 in the detection of BC cases compared to the routinely used GATA3 immunostain.

Material and methods: Seventy BC specimens and 80 specimens of non-breast carcinomas known to exhibit morphological similarity to metastatic breast cancer or show GATA3 positivity were evaluated for immunohistochemical expression of TRPS1 and GATA3. Moreover, the validity of TRPS1 in the identification of BC either alone or in combination with GATA3 was investigated.

Results: TRPS1 and GATA3 were positive in 92.9% and 80% of studied BC specimens with a specificity of 96.3% and 80%, respectively. TRPS1 was found to be more sensitive and specific than GATA3 in the detection of BC.

Conclusions: TRPS1 can be considered as a diagnostic marker of BC. TRPS1 is more sensitive and specific than GATA3 in detection of BC. The double combination of TRPS1 and GATA3 provided higher sensitivity and specificity in detection of BC.