Evaluation of cleaved caspase-3 and Ki-67 index on diagnostic biopsy in response to neoadjuvant chemotherapy in the context of post-treatment tumour ypT stage, ypN stage, grade, and molecular subtype

Introduction
Breast carcinoma is a heterogeneous disease, characterised by diverse clinical behaviour. The aim of this study was to assess how cleaved caspase-3 and Ki-67 index, evaluated on diagnostic biopsy, are related to response to neoadjuvant chemotherapy in the context of molecular subtype, post-treatment tumour, N category, and grade.

Material and methods
A retrospective analysis was carried out among 110 breast cancer patients. Ki-67 levels and caspase-3 expression on diagnostic biopsy were explored regarding their relation to tumour grade and molecular subtype, ypT, ypN categories, and T and N categories according to Sataloff tumour response evaluation.

Results
A statistically significant relationship was found between Ki-67 levels and tumour grade K-W = 24.2932, p < 0.0001; molecular subtype K-W = 28.5439, p < 0.00000967538; size and invasion of the primary tumour after neoadjuvant chemotherapy K-W = 11.7944, p < 0.0377169; caspase-3 expression after neoadjuvant therapy, evaluated according to the Sataloff classification 2 = 5.97, df = 1, p = 0.0145.

Discussion
No significant difference was found between Ki-67 expression in patients with pathological complete response, compared to those with partial and no response, a statistically significant difference in cases with different molecular subtype, histology grade, and tumour stage after neoadjuvant therapy. Cleaved caspase-3-positive breast cancer cases are often better responders to neoadjuvant therapy, but with no significant correlation to molecular subtype, high-grade categories, or tumour stage

Conclusions
The caspase-3 and Ki-67 index on diagnostic biopsy are related to post-neoadjuvant treatment prognostic factors (ypT stage, grade), proving them useful for prediction of treatment response to neoadjuvant therapy and further patient management.