Predictive factors of pathological response to neoadjuvant chemotherapy in patients with breast cancer.

Purpose: To identify predictive factors connected with pathologic response in patients with breast cancer (BC) having received neoadjuvant chemotherapy (NACT).

Methods: 49 patients with BC were investigated before and after treatment in this prospective research. Different chemotherapy regimes were administered. The Miller-Payne scoring system was used to assess the tumour response. The nuclear proliferation markers Ki67 and the expression of topoisomerase IIα (Topo IIα) were evaluated.

Results: Six patients (12.2 %) achieved pathological complete response (pCR). Noticeable decrease of tumor cellularity was detected in all BC subtypes and pCR in the triple-negative BC (TNBC) group (p=0.007) was observed. Poorly differentiated tumors could be considered as predictive factors of pCR (p=0.07). Ki67 appeared to be a predictive marker of achieving pCR (p<0.001) with a threshold of 28% (AUC=0.89, 95% CI 0.75-0.96). The additional factor of reaching pCR was operable BC (p=0.04). The expression level of Topo IIα (p=0.50) and using different regimens of NACT (p=0.97) did not influence pCR achievement.

Conclusion: To sum it up, poorly differentiated carcinomas with high cellularity in the primary tumor, TNBC, Ki 67 with a threshold above 28% and operable BC can be considered as early predictors of reaching pCR.