Semi-quantitative evaluation of estrogen receptor expression is a strong predictive factor of pathological complete response after anthracycline-based neo-adjuvant chemotherapy in hormonal-sensitive breast cancer.

Absence of hormonal receptors (HR) expression is a predictive factor of high pathologic complete response (pCR) rate after neo-adjuvant chemotherapy. However, HR-positive tumors are less chemosensitive. In the present study, we evaluated the predictive value of estrogen (ER) and progesterone (PgR) semi-quantitative expression in patients with HR-positive tumors treated uniformly with antracycline-based neoadjuvant chemotherapy without hormonal treatment. Value of HR expression as a predictive factor was then evaluated in a multivariate analysis with tumor grade, Ki67 index and HER2 expression. From January 2000 and December 2006, 177 patients with HR-positive breast ductal invasive carcinoma ≥2 cm in its largest diameter were treated with six cycles of an anthracycline-based neo-adjuvant chemotherapy. Tumor grade, ER, PgR, HER2 status and Ki67 index were determined on microbiopsy performed before chemotherapy. A semi-quantitative evaluation of ER and PgR expression by IHC was performed using the Barnes'score. pCR rate was significantly different (P < 0.001) according to the ER expression score. pCR rate was 28% for low score, 9% for medium score and 3% for high score. On the contrary, pCR rate was not significantly different (P = 0.49) according to the PgR expression score. In the multivariate analysis, ER expression score (P = 0.0002) and Ki67 index (P = 0.02) were the only predictive factors of response for HR-positive tumors. pCR after anthracycline-based chemotherapy is significantly correlated with the ER expression score.