Background: Breast cancer is cancer, with the highest incidence in women worldwide. It also has a very high mortality due to late treatment. The immunohistochemical examination is an important factor in determining breast cancer subtypes and subsequent therapy. However, neoadjuvant chemotherapy (NACT) has been reported to change the expression of immunohistochemical examinations of Estrogen Receptor (ER), Progesterone Receptor (PR), Human Epidermal Growth Factor Receptor-2 (HER-2), and Ki-67. This study aims to determine the relationship between hormonal, HER-2, and KI-67 changes after NCAT.
Method: The immunohistochemical examinations were conducted on ER, PR, HER-2, Ki-67 and histopathological grading from 59 cases of stage III breast cancer after NACT administration. We analyzed the relationship between the changes in the expression of immunohistochemical examinations on the biopsy tissue specimens before NACT administration and from the tissue mastectomy after NACT administration associated with its histopathological grading with spearman correlation analysis using SPSS version 25 for Windows.
Results: There were changes in the results of the expression of immunohistochemical examinations of ER, PR, HER-2, KI-67 and histopathological grading by 23.7%, 22.03%, 32.2%, 32.2% and 40.68% in stage III breast cancer patients who received NACT. There was a relationship with a weak correlation between the changes in immunohistochemical examinations of ER, PR, HER-2 and KI-67 with the changes in histopathological grading. The correlation coefficients between ER, PR, HER-2, Ki-67 and the histopathological grading were r=0.265, r=0.317, r=0.352 and r=0.335.
Conclusions: Patients with stage III breast cancer who were treated with NACT experienced changes in the expression of immunohistochemical examinations of ER, PR, HER-2 and KI-67 and would experience changes in histopathological grading, causing changes in the breast cancer subtypes.