Tumor budding and Ki-67 proliferation index as biomarkers for NAC response and prognosis in breast cancer.

Neoadjuvant chemotherapy (NAC) enhances the possibility of breast conserving surgery and improves survival in patients with complete response in breast carcinoma. The most crucial step for maximum benefit and minimum damage in neoadjuvant chemotherapy is selecting the most eligible patient. The study included 191 patients diagnosed with invasive breast carcinoma of no special type in needle biopsy samples. The effect of tumor budding (TB) and the Ki-67 proliferation index on NAC response and survival were assessed. Tumor budding was associated with metastasis (p < 0.001), survival (p = 0.002), and molecular subtype (p = 0.045). In multivariate analysis, TB was an independent risk factor for disease free survival (DFS). There was no significant correlation between NAC response and TB (p = 0.104). The cutoff value of the Ki-67 proliferation index in response to NAC was determined as 19%. Neoadjuvant chemotherapy response is observed more positively in tumors with KI-67 index of 19% and above. Although intratumoral TB is not detected in correlation with NAC response, it has an independent effect on DFS. Adding TB parameter to the pathology report format of needle biopsy materials has the potential to make a positive contribution to patient management.