Objective: The rates of and the factors influencing HER2 discordance in patients receiving neoadjuvant therapy for breast cancer are investigated. Methods: This study retrospectively examines the rates of HER2 and hormone receptor discordance between the biopsy and postoperative resection specimens of 400 female early-stage breast cancer patients. Results: 133 (33.3%) patients had received neoadjuvant therapy. The rate of HER2 discordance between biopsy and resection specimens was 1.7% in the control group and 5.3% in the neoadjuvant therapy group (p = 0.018). The rate of HER2 discordance was higher in younger patients and in patients with T1 tumors in the neoadjuvant therapy group. Conclusion: Neoadjuvant therapy, age <40 years and smaller tumor size were independent risk factors for HER2 discordance.
Keywords: HER2; biopsy; breast cancer; chemotherapy; discordance; estrogen receptor; neoadjuvant therapy; progesterone receptor; receptor; risk factors.
HER2 is an important and targetable molecule in breast cancer. In the early stages of breast cancer, a treatment modality called neoadjuvant therapy, which now includes anti-HER2 therapies, is administered before surgery in order to achieve disease regression and make the patient suitable for a more minor operation. In breast cancer, HER2 status may be positive in the initial biopsy specimen and negative in the surgical specimen. HER2 status plays an important role in treatment decisions. In this study, we investigated the factors causing HER2 status to change in early-stage breast cancer. This study has a retrospective design and includes 400 female patients with early-stage breast cancer. The results of the study identified the factors causing HER2 status to change to negative as receipt of neoadjuvant therapy, small tumor size and younger age.