Use of GCDFP-15 (BRST-2) as a Specific Immunocytochemical Marker for Diagnosis of Gastric Metastasis of Breast Carcinoma

Metastasis of breast cancer to the stomach is relatively uncommon and typically occurs in patients with disseminated diseases. This may cause difficulty in differentiating it from primary gastric carcinoma. The correct diagnosis of the primary source is important, since the treatment and prognosis of metastatic breast cancer is quite different from those of metastatic gastric cancer. Immunohistochemical staining with GCDFP-15 (gross cystic disease fluid protein-15) can be used to differentiate primary gastric carcinoma and gastric metastasis from breast cancer. We report two cases of gastric metastasis of breast cancer by describing their clinical course, illustrating the histologic findings, and showing the results of immunohistochemical staining with GCDFP-15.