Background: This study investigated the expression of C-KIT and HER-2 receptors and their correlation with histopathological markers of cell proliferation, differentiation and apoptosis in poor-prognosis breast cancer.
Patients and methods: Formalin-embedded histopathological samples from forty patients with progressive metastatic breast cancer were reanalyzed to determine HER-2 expression by immunohistochemistry (ICH) and chromogenic in situ hybridization (CISH). C-KIT receptor expression, p53, Bcl-2 and Ki-67 were determined by immunohistochemistry.
Results: The mean p53 score was 18.03 (SD 30.69), that of Bcl-2 was 38.13 (39.25) and Ki-67 was 5.8 (SD 9.23), respectively. HER-2 expression was positive in 35% of patients by ICH and in 25% by CISH. C-KIT receptor staining was positive in 82% of the patients. A significant association was observed between HER-2-positive score in ICH and poorly-differentiated histology (p=0.03), negative Er/Pr status (p=0.04) and Bcl-2 expression (p=0.003). With CISH-determined HER-2, the corresponding p values were 0.07, 0.053, and 0.002, respectively. No correlation was found between HER-2 or C-KIT expression (p=0.456).
Conclusion: CISH and ICH determination of HER-2 correlate similarly to hormone receptor status and Bcl-2 expression in breast cancer. C-KIT expression was commonly present and did not correlate to other prognosticators in poor-prognosis breast cancer.