Is Ki-67 Really Useful as a Predictor for Response to Neoadjuvant Chemotherapy in Locally Advanced Breast Cancer?

Area of Science:

• Oncology
• Biomarkers
• Clinical Research

Background:

• Neoadjuvant chemotherapy (NACT) is standard for locally advanced breast cancer (LABC), aiming for breast conservation or operability.
• Pathological complete response (pCR) after NACT is a key surrogate for improved survival, especially in high-grade tumors.
• Identifying predictors of pCR is crucial for tailoring treatment strategies.

Purpose of the Study:

• To evaluate the predictive value of the Ki-67 protein index for achieving pCR in LABC patients undergoing NACT.
• To explore other clinicopathological factors associated with pCR in this patient cohort.

Main Methods:

• Retrospective analysis of 105 LABC patients who completed NACT and surgery.
• Ki-67 scores assessed on pre-treatment core biopsies.
• Clinical and histopathological evaluation for response assessment (pCR and clinical complete response - cCR).
• Statistical analysis including univariate analysis and ROC curve analysis for Ki-67.

Main Results:

• 33 out of 105 patients (31.4%) achieved pCR.
• Mean Ki-67 index was 46.44% ± 22.92% in the overall population.
• No significant association was found between Ki-67 levels and pCR (pCR group mean Ki-67: 51.60% vs. no pCR group: 44.06%).
• Estrogen receptor negativity, progesterone receptor negativity, and HER2 positivity were predictive of pCR.
• Triple-negative breast cancer (TNBC) and HER2-positive subgroups showed higher rates of cCR and pCR.

Conclusions:

• Ki-67 index did not demonstrate significant predictive value for pCR in this LABC cohort treated with NACT.
• Hormone receptor status and HER2 status appear to be stronger predictors of pCR.
• The COVID-19 pandemic may have confounded results; further validation in larger prospective studies is warranted.