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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.